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id="toc-Description-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Systems" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Systems"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Systems</span> </div> </a> <button aria-controls="toc-Systems-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Systems subsection</span> </button> <ul id="toc-Systems-sublist" class="vector-toc-list"> <li id="toc-Musculoskeletal" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Musculoskeletal"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Musculoskeletal</span> </div> </a> <ul id="toc-Musculoskeletal-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Feeding_and_digestion" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Feeding_and_digestion"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Feeding and digestion</span> </div> </a> <ul id="toc-Feeding_and_digestion-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Circulation_and_respiration" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Circulation_and_respiration"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Circulation and respiration</span> </div> </a> <ul id="toc-Circulation_and_respiration-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Nervous_system_and_senses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Nervous_system_and_senses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Nervous system and senses</span> </div> </a> <ul id="toc-Nervous_system_and_senses-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Life_history" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Life_history"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Life history</span> </div> </a> <button aria-controls="toc-Life_history-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Life history subsection</span> </button> <ul id="toc-Life_history-sublist" class="vector-toc-list"> <li id="toc-Reproduction" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Reproduction"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Reproduction</span> </div> </a> <ul id="toc-Reproduction-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Development" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Development"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Development</span> </div> </a> <ul id="toc-Development-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Life_cycle_and_development" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Life_cycle_and_development"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Life cycle and development</span> </div> </a> <ul id="toc-Life_cycle_and_development-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Longevity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Longevity"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Longevity</span> </div> </a> <ul id="toc-Longevity-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Ecology" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Ecology"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Ecology</span> </div> </a> <button aria-controls="toc-Ecology-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Ecology subsection</span> </button> <ul id="toc-Ecology-sublist" class="vector-toc-list"> <li id="toc-Trophic_level" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Trophic_level"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Trophic level</span> </div> </a> <ul id="toc-Trophic_level-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Predators,_parasites,_and_diseases" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Predators,_parasites,_and_diseases"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Predators, parasites, and diseases</span> </div> </a> <ul id="toc-Predators,_parasites,_and_diseases-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Anti-predator_defences" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Anti-predator_defences"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Anti-predator defences</span> </div> </a> <ul id="toc-Anti-predator_defences-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Range_and_habitat" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Range_and_habitat"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Range and habitat</span> </div> </a> <ul id="toc-Range_and_habitat-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Evolution" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Evolution"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Evolution</span> </div> </a> <button aria-controls="toc-Evolution-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Evolution subsection</span> </button> <ul id="toc-Evolution-sublist" class="vector-toc-list"> <li id="toc-Fossil_history" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fossil_history"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Fossil history</span> </div> </a> <ul id="toc-Fossil_history-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Phylogeny" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Phylogeny"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2</span> <span>Phylogeny</span> </div> </a> <ul id="toc-Phylogeny-sublist" class="vector-toc-list"> <li id="toc-External" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#External"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2.1</span> <span>External</span> </div> </a> <ul id="toc-External-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Internal" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Internal"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2.2</span> <span>Internal</span> </div> </a> <ul id="toc-Internal-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Relation_to_humans" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Relation_to_humans"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Relation to humans</span> </div> </a> <button aria-controls="toc-Relation_to_humans-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Relation to humans subsection</span> </button> <ul id="toc-Relation_to_humans-sublist" class="vector-toc-list"> <li id="toc-Injuries" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Injuries"> <div class="vector-toc-text"> <span class="vector-toc-numb">7.1</span> <span>Injuries</span> </div> </a> <ul id="toc-Injuries-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Science" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Science"> <div class="vector-toc-text"> <span class="vector-toc-numb">7.2</span> <span>Science</span> </div> </a> <ul id="toc-Science-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-As_food" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#As_food"> <div class="vector-toc-text"> <span class="vector-toc-numb">7.3</span> <span>As food</span> </div> </a> <ul id="toc-As_food-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Aquaria" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Aquaria"> <div class="vector-toc-text"> <span class="vector-toc-numb">7.4</span> <span>Aquaria</span> </div> </a> <ul id="toc-Aquaria-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Folklore" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Folklore"> <div class="vector-toc-text"> <span class="vector-toc-numb">7.5</span> <span>Folklore</span> </div> </a> <ul id="toc-Folklore-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Explanatory_notes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Explanatory_notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Explanatory notes</span> </div> </a> <ul id="toc-Explanatory_notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Sea urchin</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 89 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-89" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">89 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Afrikaans" lang="af" hreflang="af" data-title="Echinoidea" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%82%D9%86%D9%81%D8%B0_%D8%A7%D9%84%D8%A8%D8%AD%D8%B1" title="قنفذ البحر – Arabic" lang="ar" hreflang="ar" data-title="قنفذ البحر" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Equinoidea" title="Equinoidea – Asturian" lang="ast" hreflang="ast" data-title="Equinoidea" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/D%C9%99niz_kirpil%C9%99ri" title="Dəniz kirpiləri – Azerbaijani" lang="az" hreflang="az" data-title="Dəniz kirpiləri" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D8%AF%D9%86%DB%8C%D8%B2_%DA%A9%DB%8C%D8%B1%D9%BE%DB%8C%D9%84%D8%B1%DB%8C" title="دنیز کیرپیلری – South Azerbaijani" lang="azb" hreflang="azb" data-title="دنیز کیرپیلری" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target"><span>تۆرکجه</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9C%D0%B0%D1%80%D1%81%D0%BA%D1%96%D1%8F_%D0%B2%D0%BE%D0%B6%D1%8B%D0%BA%D1%96" title="Марскія вожыкі – Belarusian" lang="be" hreflang="be" data-title="Марскія вожыкі" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9C%D0%B0%D1%80%D1%81%D0%BA%D1%96%D1%8F_%D0%B2%D0%BE%D0%B6%D1%8B%D0%BA%D1%96" title="Марскія вожыкі – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Марскія вожыкі" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bcl mw-list-item"><a href="https://bcl.wikipedia.org/wiki/Tayom" title="Tayom – Central Bikol" lang="bcl" hreflang="bcl" data-title="Tayom" data-language-autonym="Bikol Central" data-language-local-name="Central Bikol" class="interlanguage-link-target"><span>Bikol Central</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D1%81%D0%BA%D0%B8_%D1%82%D0%B0%D1%80%D0%B0%D0%BB%D0%B5%D0%B6%D0%B8" title="Морски таралежи – Bulgarian" lang="bg" hreflang="bg" data-title="Морски таралежи" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Morski_je%C5%BEevi" title="Morski ježevi – Bosnian" lang="bs" hreflang="bs" data-title="Morski ježevi" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Teureug" title="Teureug – Breton" lang="br" hreflang="br" data-title="Teureug" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Eri%C3%A7ons_de_mar" title="Eriçons de mar – Catalan" lang="ca" hreflang="ca" data-title="Eriçons de mar" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-ceb mw-list-item"><a href="https://ceb.wikipedia.org/wiki/Swakigtuyom" title="Swakigtuyom – Cebuano" lang="ceb" hreflang="ceb" data-title="Swakigtuyom" data-language-autonym="Cebuano" data-language-local-name="Cebuano" class="interlanguage-link-target"><span>Cebuano</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Je%C5%BEovky" title="Ježovky – Czech" lang="cs" hreflang="cs" data-title="Ježovky" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-ny mw-list-item"><a href="https://ny.wikipedia.org/wiki/Ma_urchins_am%27nyanja" title="Ma urchins am'nyanja – Nyanja" lang="ny" hreflang="ny" data-title="Ma urchins am'nyanja" data-language-autonym="Chi-Chewa" data-language-local-name="Nyanja" class="interlanguage-link-target"><span>Chi-Chewa</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/S%C3%B8pindsvin" title="Søpindsvin – Danish" lang="da" hreflang="da" data-title="Søpindsvin" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Seeigel" title="Seeigel – German" lang="de" hreflang="de" data-title="Seeigel" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-nv mw-list-item"><a href="https://nv.wikipedia.org/wiki/T%C3%A1%C5%82t%C5%82%CA%BC%C3%A1%C3%A1h_adiji%C5%82ii" title="Táłtłʼááh adijiłii – Navajo" lang="nv" hreflang="nv" data-title="Táłtłʼááh adijiłii" data-language-autonym="Diné bizaad" data-language-local-name="Navajo" class="interlanguage-link-target"><span>Diné bizaad</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Merisiilikud" title="Merisiilikud – Estonian" lang="et" hreflang="et" data-title="Merisiilikud" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%91%CF%87%CE%B9%CE%BD%CF%8C%CF%82" title="Αχινός – Greek" lang="el" hreflang="el" data-title="Αχινός" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-myv mw-list-item"><a href="https://myv.wikipedia.org/wiki/%D0%92%D0%B5%D0%B4%D1%8C%D1%81%D0%B5%D0%B5%D0%BB%D1%8C" title="Ведьсеель – Erzya" lang="myv" hreflang="myv" data-title="Ведьсеель" data-language-autonym="Эрзянь" data-language-local-name="Erzya" class="interlanguage-link-target"><span>Эрзянь</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Spanish" lang="es" hreflang="es" data-title="Echinoidea" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/E%C4%A5ino" title="Eĥino – Esperanto" lang="eo" hreflang="eo" data-title="Eĥino" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Itsas_triku" title="Itsas triku – Basque" lang="eu" hreflang="eu" data-title="Itsas triku" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D9%88%D8%AA%DB%8C%D8%A7%DB%8C_%D8%AF%D8%B1%DB%8C%D8%A7%DB%8C%DB%8C" title="توتیای دریایی – Persian" lang="fa" hreflang="fa" data-title="توتیای دریایی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Echinoidea" title="Echinoidea – French" lang="fr" hreflang="fr" data-title="Echinoidea" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Cu%C3%A1n_mara" title="Cuán mara – Irish" lang="ga" hreflang="ga" data-title="Cuán mara" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Ourizo_de_mar" title="Ourizo de mar – Galician" lang="gl" hreflang="gl" data-title="Ourizo de mar" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%84%B1%EA%B2%8C%EB%A5%98" title="성게류 – Korean" lang="ko" hreflang="ko" data-title="성게류" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%BE%D5%B8%D5%BE%D5%B8%D5%A6%D5%B6%D5%AB%D5%B6%D5%A5%D6%80" title="Ծովոզնիներ – Armenian" lang="hy" hreflang="hy" data-title="Ծովոզնիներ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%9C%E0%A4%B2%E0%A4%B8%E0%A4%BE%E0%A4%B9%E0%A5%80" title="जलसाही – Hindi" lang="hi" hreflang="hi" data-title="जलसाही" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Je%C5%BEinci" title="Ježinci – Croatian" lang="hr" hreflang="hr" data-title="Ježinci" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/Ekino" title="Ekino – Ido" lang="io" hreflang="io" data-title="Ekino" data-language-autonym="Ido" data-language-local-name="Ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Landak_laut" title="Landak laut – Indonesian" lang="id" hreflang="id" data-title="Landak laut" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/%C3%8Dgulker" title="Ígulker – Icelandic" lang="is" hreflang="is" data-title="Ígulker" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Italian" lang="it" hreflang="it" data-title="Echinoidea" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A7%D7%99%D7%A4%D7%95%D7%93%D7%99_%D7%99%D7%9D" title="קיפודי ים – Hebrew" lang="he" hreflang="he" data-title="קיפודי ים" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%96%E1%83%A6%E1%83%95%E1%83%98%E1%83%A1_%E1%83%96%E1%83%A6%E1%83%90%E1%83%A0%E1%83%91%E1%83%94%E1%83%91%E1%83%98" title="ზღვის ზღარბები – Georgian" lang="ka" hreflang="ka" data-title="ზღვის ზღარბები" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A2%D0%B5%D2%A3%D1%96%D0%B7_%D0%BA%D1%96%D1%80%D0%BF%D1%96%D0%BB%D0%B5%D1%80%D1%96" title="Теңіз кірпілері – Kazakh" lang="kk" hreflang="kk" data-title="Теңіз кірпілері" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%94%D0%B5%D2%A3%D0%B8%D0%B7_%D0%BA%D0%B8%D1%80%D0%BF%D0%B8%D1%81%D0%B8" title="Деңиз кирписи – Kyrgyz" lang="ky" hreflang="ky" data-title="Деңиз кирписи" data-language-autonym="Кыргызча" data-language-local-name="Kyrgyz" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-mrj mw-list-item"><a href="https://mrj.wikipedia.org/wiki/%D0%A2%D0%B0%D0%BD%D0%B3%D1%8B%D0%B6_%D1%88%D3%B1%D0%BB%D3%B9" title="Тангыж шӱлӹ – Western Mari" lang="mrj" hreflang="mrj" data-title="Тангыж шӱлӹ" data-language-autonym="Кырык мары" data-language-local-name="Western Mari" class="interlanguage-link-target"><span>Кырык мары</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Latin" lang="la" hreflang="la" data-title="Echinoidea" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/J%C5%ABras_e%C5%BEi" title="Jūras eži – Latvian" lang="lv" hreflang="lv" data-title="Jūras eži" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/J%C5%ABr%C5%B3_e%C5%BEiai" title="Jūrų ežiai – Lithuanian" lang="lt" hreflang="lt" data-title="Jūrų ežiai" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/Zie%C3%AB-eechele" title="Zieë-eechele – Limburgish" lang="li" hreflang="li" data-title="Zieë-eechele" data-language-autonym="Limburgs" data-language-local-name="Limburgish" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-lfn mw-list-item"><a href="https://lfn.wikipedia.org/wiki/Ecinoideo" title="Ecinoideo – Lingua Franca Nova" lang="lfn" hreflang="lfn" data-title="Ecinoideo" data-language-autonym="Lingua Franca Nova" data-language-local-name="Lingua Franca Nova" class="interlanguage-link-target"><span>Lingua Franca Nova</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Tengeris%C3%BCn%C3%B6k" title="Tengerisünök – Hungarian" lang="hu" hreflang="hu" data-title="Tengerisünök" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D1%81%D0%BA%D0%B8_%D0%B5%D0%B6%D0%BE%D0%B2%D0%B8" title="Морски ежови – Macedonian" lang="mk" hreflang="mk" data-title="Морски ежови" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-mg mw-list-item"><a href="https://mg.wikipedia.org/wiki/Soky" title="Soky – Malagasy" lang="mg" hreflang="mg" data-title="Soky" data-language-autonym="Malagasy" data-language-local-name="Malagasy" class="interlanguage-link-target"><span>Malagasy</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%95%E0%B4%9F%E0%B5%BD%E0%B4%9A%E0%B5%8D%E0%B4%9A%E0%B5%87%E0%B4%A8" title="കടൽച്ചേന – Malayalam" lang="ml" hreflang="ml" data-title="കടൽച്ചേന" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-arz mw-list-item"><a href="https://arz.wikipedia.org/wiki/%D9%82%D9%86%D9%81%D8%B0_%D8%A7%D9%84%D8%A8%D8%AD%D8%B1" title="قنفذ البحر – Egyptian Arabic" lang="arz" hreflang="arz" data-title="قنفذ البحر" data-language-autonym="مصرى" data-language-local-name="Egyptian Arabic" class="interlanguage-link-target"><span>مصرى</span></a></li><li class="interlanguage-link interwiki-mnw mw-list-item"><a href="https://mnw.wikipedia.org/wiki/%E1%80%80%E1%81%9E%E1%80%AF%E1%80%81%E1%80%BB" title="ကၞုချ – Mon" lang="mnw" hreflang="mnw" data-title="ကၞုချ" data-language-autonym="ဘာသာမန်" data-language-local-name="Mon" class="interlanguage-link-target"><span>ဘာသာမန်</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Landak_laut" title="Landak laut – Malay" lang="ms" hreflang="ms" data-title="Landak laut" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%9E%E1%80%B6%E1%80%95%E1%80%81%E1%80%BC%E1%80%AF%E1%80%95%E1%80%BA" title="သံပခြုပ် – Burmese" lang="my" hreflang="my" data-title="သံပခြုပ်" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Zee-egels" title="Zee-egels – Dutch" lang="nl" hreflang="nl" data-title="Zee-egels" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%A6%E3%83%8B" title="ウニ – Japanese" lang="ja" hreflang="ja" data-title="ウニ" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/Siaiigler" title="Siaiigler – Northern Frisian" lang="frr" hreflang="frr" data-title="Siaiigler" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Sj%C3%B8piggsvin" title="Sjøpiggsvin – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Sjøpiggsvin" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Kr%C3%A5kebolle" title="Kråkebolle – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Kråkebolle" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Occitan" lang="oc" hreflang="oc" data-title="Echinoidea" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Dengiz_tipratikanlari" title="Dengiz tipratikanlari – Uzbek" lang="uz" hreflang="uz" data-title="Dengiz tipratikanlari" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Je%C5%BCowce" title="Jeżowce – Polish" lang="pl" hreflang="pl" data-title="Jeżowce" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Portuguese" lang="pt" hreflang="pt" data-title="Echinoidea" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Echinoide" title="Echinoide – Romanian" lang="ro" hreflang="ro" data-title="Echinoide" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-qu mw-list-item"><a href="https://qu.wikipedia.org/wiki/Yaku_askanku" title="Yaku askanku – Quechua" lang="qu" hreflang="qu" data-title="Yaku askanku" data-language-autonym="Runa Simi" data-language-local-name="Quechua" class="interlanguage-link-target"><span>Runa Simi</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D1%81%D0%BA%D0%B8%D0%B5_%D0%B5%D0%B6%D0%B8" title="Морские ежи – Russian" lang="ru" hreflang="ru" data-title="Морские ежи" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Sea_urchin" title="Sea urchin – Scots" lang="sco" hreflang="sco" data-title="Sea urchin" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/Echinoidea" title="Echinoidea – Sicilian" lang="scn" hreflang="scn" data-title="Echinoidea" data-language-autonym="Sicilianu" data-language-local-name="Sicilian" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Sea_urchin" title="Sea urchin – Simple English" lang="en-simple" hreflang="en-simple" data-title="Sea urchin" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Je%C5%BEovky" title="Ježovky – Slovak" lang="sk" hreflang="sk" data-title="Ježovky" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Morski_je%C5%BEki" title="Morski ježki – Slovenian" lang="sl" hreflang="sl" data-title="Morski ježki" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9C%D0%BE%D1%80%D1%81%D0%BA%D0%B8_%D1%98%D0%B5%D0%B6%D0%B5%D0%B2%D0%B8" title="Морски јежеви – Serbian" lang="sr" hreflang="sr" data-title="Морски јежеви" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Je%C5%BEinci" title="Ježinci – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Ježinci" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Merisiilit" title="Merisiilit – Finnish" lang="fi" hreflang="fi" data-title="Merisiilit" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Sj%C3%B6borrar" title="Sjöborrar – Swedish" lang="sv" hreflang="sv" data-title="Sjöborrar" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Salungo" title="Salungo – Tagalog" lang="tl" hreflang="tl" data-title="Salungo" 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Click here for more information." src="//upload.wikimedia.org/wikipedia/en/thumb/9/94/Symbol_support_vote.svg/19px-Symbol_support_vote.svg.png" decoding="async" width="19" height="20" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/94/Symbol_support_vote.svg/29px-Symbol_support_vote.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/94/Symbol_support_vote.svg/39px-Symbol_support_vote.svg.png 2x" data-file-width="180" data-file-height="185" /></a></span></div></div> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Class of marine invertebrates</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/Sea_Urchin_(disambiguation)" class="mw-disambig" title="Sea Urchin (disambiguation)">Sea Urchin (disambiguation)</a>.</div> <p class="mw-empty-elt"> </p> <table class="infobox biota" style="text-align: left; width: 200px; font-size: 100%"> <tbody><tr> <th colspan="2" style="color:inherit; text-align: center; background-color: rgb(235,235,210)">Sea urchin<br /><div style="font-size: 85%;">Temporal range: <span class="noprint"><span style="display:inline-block;"></span><span style="display:inline-block;">Ordovician–Present</span> <span style="display:inline-block;"></span><div id="Timeline-row" style="margin: 4px auto 0; clear:both; width:220px; padding:0px; height:18px; overflow:visible; white-space:nowrap; border:1px #666; border-style:solid none; position:relative; z-index:0; font-size:97%;"> <div style="position:absolute; height:100%; left:0px; width:207.23076923077px; padding-left:5px; text-align:left; background-color:rgb(254,217,106); background-image: linear-gradient(to right, rgba(255,255,255,1), rgba(254,217,106,1) 15%, rgba(254,217,106,1));"><a href="/wiki/Precambrian" title="Precambrian">PreꞒ</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(127,160,86); left:37.636923076923px; width:17.583076923077px;"><a href="/wiki/Cambrian" title="Cambrian">Ꞓ</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(0,146,112); left:55.22px; width:14.807692307692px;"><a href="/wiki/Ordovician" title="Ordovician">O</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(179,225,182); left:70.027692307692px; width:7.9470769230769px;"><a href="/wiki/Silurian" title="Silurian">S</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(203,140,55); left:77.974769230769px; width:20.564923076923px;"><a href="/wiki/Devonian" title="Devonian">D</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(103,165,153); left:98.539692307692px; width:20.294153846154px;"><a href="/wiki/Carboniferous" title="Carboniferous">C</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(240,64,40); left:118.83384615385px; width:15.907015384615px;"><a href="/wiki/Permian" title="Permian">P</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(129,43,146); left:134.74086153846px; width:17.092984615385px;"><a href="/wiki/Triassic" title="Triassic">T</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(52,178,201); left:151.83384615385px; width:19.732307692308px;"><a href="/wiki/Jurassic" title="Jurassic">J</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(127,198,78); left:171.56615384615px; width:26.095384615385px;"><a href="/wiki/Cretaceous" title="Cretaceous">K</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(253,154,82); left:197.66153846154px; width:14.540307692308px;"><a href="/wiki/Paleogene" title="Paleogene">Pg</a></div> <div style="position:absolute; height:100%; text-align:center; background-color:rgb(255,230,25); left:212.20184615385px; width:6.9249230769231px;"><a href="/wiki/Neogene" title="Neogene">N</a></div> <div id="end-border" style="position:absolute; height:100%; background-color:#666; width:1px; left:219px"></div><div style="margin:0 auto; line-height:0; clear:both; width:220px; padding:0px; height:8px; overflow:visible; background-color:transparent; position:relative; top:-4px; z-index:100;"><div style="position:absolute; height:8px; left:55.22px; width:164.78px; background-color:#360; opacity:0.42;"></div> <div style="position:absolute; height:8px; left:55.22px; width:164.78px; background-color:#360; opacity:1;"></div> <div style="position:absolute; height:6px; top:1px; left:56.22px; width:162.78px; background-color:#6c3;"></div> </div> </div></span></div> </th></tr> <tr> <td colspan="2" style="text-align: center"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:Tripneustes_ventricosus_(West_Indian_Sea_Egg-top)_and_Echinometra_viridis_(Reef_Urchin_-_bottom).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Tripneustes_ventricosus_%28West_Indian_Sea_Egg-top%29_and_Echinometra_viridis_%28Reef_Urchin_-_bottom%29.jpg/250px-Tripneustes_ventricosus_%28West_Indian_Sea_Egg-top%29_and_Echinometra_viridis_%28Reef_Urchin_-_bottom%29.jpg" decoding="async" width="250" height="334" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Tripneustes_ventricosus_%28West_Indian_Sea_Egg-top%29_and_Echinometra_viridis_%28Reef_Urchin_-_bottom%29.jpg/500px-Tripneustes_ventricosus_%28West_Indian_Sea_Egg-top%29_and_Echinometra_viridis_%28Reef_Urchin_-_bottom%29.jpg 1.5x" data-file-width="1822" data-file-height="2431" /></a></span> </td></tr> <tr> <td colspan="2" style="text-align: center; font-size: 88%"><i><a href="/wiki/Tripneustes_ventricosus" title="Tripneustes ventricosus">Tripneustes ventricosus</a></i> and <i><a href="/wiki/Echinometra_viridis" title="Echinometra viridis">Echinometra viridis</a></i> </td></tr> <tr> <th colspan="2" style="color:inherit; min-width:15em; text-align: center; background-color: rgb(235,235,210)"><a href="/wiki/Taxonomy_(biology)" title="Taxonomy (biology)">Scientific classification</a> <span class="plainlinks taxobox-edit-taxonomy skin-invert" style="font-size:smaller; float:right; padding-right:0.4em; margin-left:-3em;"><span typeof="mw:File"><a href="/wiki/Template:Taxonomy/Echinoidea" title="Edit this classification"><img alt="Edit this classification" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/OOjs_UI_icon_edit-ltr.svg/15px-OOjs_UI_icon_edit-ltr.svg.png" decoding="async" width="15" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/OOjs_UI_icon_edit-ltr.svg/23px-OOjs_UI_icon_edit-ltr.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8a/OOjs_UI_icon_edit-ltr.svg/30px-OOjs_UI_icon_edit-ltr.svg.png 2x" data-file-width="20" data-file-height="20" /></a></span></span> </th></tr> <tr> <td>Domain: </td> <td><a href="/wiki/Eukaryote" title="Eukaryote">Eukaryota</a> </td></tr> <tr> <td>Kingdom: </td> <td><a href="/wiki/Animal" title="Animal">Animalia</a> </td></tr> <tr> <td>Phylum: </td> <td><a href="/wiki/Echinoderm" title="Echinoderm">Echinodermata</a> </td></tr> <tr> <td>Subphylum: </td> <td><a href="/wiki/Echinozoa" title="Echinozoa">Echinozoa</a> </td></tr> <tr> <td>Class: </td> <td><a class="mw-selflink selflink">Echinoidea</a><br /><small><a href="/wiki/Leske" class="mw-redirect" title="Leske">Leske</a>, 1778</small> </td></tr> <tr> <th colspan="2" style="color:inherit; text-align: center; background-color: rgb(235,235,210)">Subclasses </th></tr> <tr> <td colspan="2" style="text-align: left"> <ul><li>Subclass <a href="/wiki/Perischoechinoidea" title="Perischoechinoidea">Perischoechinoidea</a> <ul><li>Order <a href="/wiki/Cidaroida" title="Cidaroida">Cidaroida</a> (pencil urchins)</li></ul></li> <li>Subclass <a href="/wiki/Euechinoidea" title="Euechinoidea">Euechinoidea</a> <ul><li>Superorder <a href="/wiki/Atelostomata" title="Atelostomata">Atelostomata</a> <ul><li>Order <a href="/wiki/Cassiduloida" title="Cassiduloida">Cassiduloida</a></li> <li>Order <a href="/wiki/Spatangoida" title="Spatangoida">Spatangoida</a> (heart urchins)</li></ul></li> <li>Superorder <a href="/wiki/Diadematacea" class="mw-redirect" title="Diadematacea">Diadematacea</a> <ul><li>Order <a href="/wiki/Diadematoida" title="Diadematoida">Diadematoida</a></li> <li>Order <a href="/wiki/Echinothurioida" title="Echinothurioida">Echinothurioida</a></li> <li>Order <a href="/wiki/Pedinoida" title="Pedinoida">Pedinoida</a></li></ul></li> <li>Superorder <a href="/wiki/Echinacea_(animal)" title="Echinacea (animal)">Echinacea</a> <ul><li>Order <a href="/wiki/Arbacioida" title="Arbacioida">Arbacioida</a></li> <li>Order <a href="/wiki/Echinoida" title="Echinoida">Echinoida</a></li> <li>Order <a href="/wiki/Phymosomatoida" title="Phymosomatoida">Phymosomatoida</a></li> <li>Order <a href="/wiki/Salenioida" title="Salenioida">Salenioida</a></li> <li>Order <a href="/wiki/Temnopleuroida" class="mw-redirect" title="Temnopleuroida">Temnopleuroida</a></li></ul></li> <li>Superorder <a href="/wiki/Gnathostomata_(echinoid)" title="Gnathostomata (echinoid)">Gnathostomata</a> <ul><li>Order <a href="/wiki/Clypeasteroida" class="mw-redirect" title="Clypeasteroida">Clypeasteroida</a> (sand dollars)</li> <li>Order <a href="/wiki/Holectypoida" title="Holectypoida">Holectypoida</a></li></ul></li></ul></li></ul> </td></tr> </tbody></table><style data-mw-deduplicate="TemplateStyles:r1238732961">@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-night .mw-parser-output .infobox.biota img{background:transparent}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .infobox.biota img{background:white}}.mw-parser-output .infobox.biota .taxobox-edit-taxonomy img{background:transparent!important}body.skin-vector .mw-parser-output table.biota.infobox{margin-top:0.5em}body.skin--responsive .mw-parser-output table.biota.infobox tr.taxonrow td{padding:2px 10px}</style> <p><b>Sea urchins</b> or <b>urchins</b> (<span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="/ɜːr/: 'ur' in 'fur'">ɜːr</span><span title="/tʃ/: 'ch' in 'China'">tʃ</span><span title="/ɪ/: 'i' in 'kit'">ɪ</span><span title="'n' in 'nigh'">n</span><span title="'z' in 'zoom'">z</span></span>/</a></span></span>) are typically <a href="/wiki/Spine_(zoology)" title="Spine (zoology)">spiny</a>, globular <a href="/wiki/Animals" class="mw-redirect" title="Animals">animals</a>, <a href="/wiki/Echinoderm" title="Echinoderm">echinoderms</a> in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms).<sup id="cite_ref-adw_1-0" class="reference"><a href="#cite_note-adw-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Their <a href="/wiki/Test_(biology)" title="Test (biology)">tests</a> (hard shells) are round and spiny, typically from 3 to 10 cm (1 to 4 in) across. Sea urchins move slowly, crawling with their <a href="/wiki/Tube_feet" title="Tube feet">tube feet</a>, and sometimes pushing themselves with their spines. They feed primarily on <a href="/wiki/Algae" title="Algae">algae</a> but also eat slow-moving or <a href="/wiki/Sessility_(motility)" title="Sessility (motility)">sessile</a> animals. Their <a href="/wiki/Predators" class="mw-redirect" title="Predators">predators</a> include <a href="/wiki/Shark" title="Shark">sharks</a>, <a href="/wiki/Sea_otter" title="Sea otter">sea otters</a>, <a href="/wiki/Starfish" title="Starfish">starfish</a>, <a href="/wiki/Wolf_eel" title="Wolf eel">wolf eels</a>, and <a href="/wiki/Triggerfish" title="Triggerfish">triggerfish</a>. </p><p>Like all echinoderms, adult sea urchins have pentagonal symmetry with their <a href="/wiki/Echinoderm#Larval_development" title="Echinoderm">pluteus larvae</a> featuring <a href="/wiki/Bilateral_symmetry" class="mw-redirect" title="Bilateral symmetry">bilateral (mirror) symmetry</a>; The latter indicates that they belong to the <a href="/wiki/Bilateria" title="Bilateria">Bilateria</a>, along with <a href="/wiki/Chordate" title="Chordate">chordates</a>, <a href="/wiki/Arthropod" title="Arthropod">arthropods</a>, <a href="/wiki/Annelid" title="Annelid">annelids</a> and <a href="/wiki/Mollusc" class="mw-redirect" title="Mollusc">molluscs</a>. Sea urchins are found in every ocean and in every climate, from the <a href="/wiki/Tropics" title="Tropics">tropics</a> to the <a href="/wiki/Polar_regions" class="mw-redirect" title="Polar regions">polar regions</a>, and inhabit marine benthic (sea bed) habitats, from rocky shores to <a href="/wiki/Hadal_zone" title="Hadal zone">hadal zone</a> depths. The fossil record of the <i>Echinoids</i> dates from the <a href="/wiki/Ordovician" title="Ordovician">Ordovician</a> period, some 450 million years ago. The closest echinoderm relatives of the sea urchin are the <a href="/wiki/Sea_cucumber" title="Sea cucumber">sea cucumbers</a> (Holothuroidea), which like them are <a href="/wiki/Deuterostome" title="Deuterostome">deuterostomes</a>, a clade that includes the <a href="/wiki/Chordate" title="Chordate">chordates</a>. (<a href="/wiki/Sand_dollar" title="Sand dollar">Sand dollars</a> are a separate order in the sea urchin class Echinoidea.) </p><p>The animals have been studied since the 19th century as <a href="/wiki/Model_organism" title="Model organism">model organisms</a> in <a href="/wiki/Developmental_biology" title="Developmental biology">developmental biology</a>, as their embryos were easy to observe. That has continued with studies of their <a href="/wiki/Genome" title="Genome">genomes</a> because of their unusual fivefold symmetry and relationship to chordates. Species such as the <a href="/wiki/Eucidaris_tribuloides" title="Eucidaris tribuloides">slate pencil urchin</a> are popular in aquaria, where they are useful for controlling algae. Fossil urchins have been used as protective <a href="/wiki/Amulet" title="Amulet">amulets</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Diversity">Diversity</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=1" title="Edit section: Diversity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/List_of_echinodermata_orders" class="mw-redirect" title="List of echinodermata orders">List of echinodermata orders</a></div> <p>Sea urchins are members of the <a href="/wiki/Phylum" title="Phylum">phylum</a> <a href="/wiki/Echinoderm" title="Echinoderm">Echinodermata</a>, which also includes <a href="/wiki/Starfish" title="Starfish">starfish</a>, <a href="/wiki/Sea_cucumbers" class="mw-redirect" title="Sea cucumbers">sea cucumbers</a>, <a href="/wiki/Sand_dollar" title="Sand dollar">sand dollars</a>, <a href="/wiki/Brittle_star" title="Brittle star">brittle stars</a>, and <a href="/wiki/Crinoid" title="Crinoid">crinoids</a>. Like other echinoderms, they have five-fold symmetry (called <a href="/wiki/Pentamerism" class="mw-redirect" title="Pentamerism">pentamerism</a>) and move by means of hundreds of tiny, transparent, adhesive "<a href="/wiki/Tube_feet" title="Tube feet">tube feet</a>". The symmetry is not obvious in the living animal, but is easily visible in the dried <a href="/wiki/Test_(biology)" title="Test (biology)">test</a>.<sup id="cite_ref-Ruppert_2-0" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Specifically, the term "sea urchin" refers to the "regular echinoids", which are symmetrical and globular, and includes several different taxonomic groups, with two subclasses: <a href="/wiki/Euechinoidea" title="Euechinoidea">Euechinoidea</a> ("modern" sea urchins, including irregular ones) and <a href="/wiki/Cidaroidea" class="mw-redirect" title="Cidaroidea">Cidaroidea</a>, or "slate-pencil urchins", which have very thick, blunt spines, with algae and sponges growing on them. The "irregular" sea urchins are an infra-class inside the Euechinoidea, called <a href="/wiki/Irregularia" title="Irregularia">Irregularia</a>, and include <a href="/wiki/Atelostomata" title="Atelostomata">Atelostomata</a> and <a href="/wiki/Neognathostomata" title="Neognathostomata">Neognathostomata</a>. Irregular echinoids include flattened <a href="/wiki/Sand_dollar" title="Sand dollar">sand dollars</a>, <a href="/wiki/Clypeasteroida" class="mw-redirect" title="Clypeasteroida">sea biscuits</a>, and <a href="/wiki/Echinocardium" title="Echinocardium">heart urchins</a>.<sup id="cite_ref-WoRMS_3-0" class="reference"><a href="#cite_note-WoRMS-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>Together with sea cucumbers (<a href="/wiki/Holothuroidea" class="mw-redirect" title="Holothuroidea">Holothuroidea</a>), they make up the subphylum <a href="/wiki/Echinozoa" title="Echinozoa">Echinozoa</a>, which is characterized by a globoid shape without arms or projecting rays. Sea cucumbers and the irregular echinoids have secondarily evolved diverse shapes. Although many sea cucumbers have branched <a href="/wiki/Tentacle" title="Tentacle">tentacles</a> surrounding their oral openings, these have originated from modified tube feet and are not homologous to the arms of the crinoids, sea stars, and brittle stars.<sup id="cite_ref-Ruppert_2-1" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-packed" style="text-align:center;"> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Paracentrotus_lividus_profil.JPG" class="mw-file-description" title="Paracentrotus lividus, a regular sea urchin (Euechinoidea, infraclass Carinacea)"><img alt="Paracentrotus lividus, a regular sea urchin (Euechinoidea, infraclass Carinacea)" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Paracentrotus_lividus_profil.JPG/250px-Paracentrotus_lividus_profil.JPG" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Paracentrotus_lividus_profil.JPG/500px-Paracentrotus_lividus_profil.JPG 1.5x" data-file-width="3482" data-file-height="2609" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Paracentrotus_lividus" title="Paracentrotus lividus">Paracentrotus lividus</a></i>, a regular sea urchin (<a href="/wiki/Euechinoidea" title="Euechinoidea">Euechinoidea</a>, infraclass <a href="/wiki/Carinacea" title="Carinacea">Carinacea</a>)</div> </li> <li class="gallerybox" style="width: 179.33333333333px"> <div class="thumb" style="width: 177.33333333333px;"><span typeof="mw:File"><a href="/wiki/File:Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg" class="mw-file-description" title="A sand dollar, an irregular sea urchin (Irregularia)"><img alt="A sand dollar, an irregular sea urchin (Irregularia)" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg/266px-Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg" decoding="async" width="178" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg/399px-Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg/531px-Live_Sand_Dollar_trying_to_bury_itself_in_beach_sand.jpg 2x" data-file-width="2532" data-file-height="1716" /></a></span></div> <div class="gallerytext">A <a href="/wiki/Sand_dollar" title="Sand dollar">sand dollar</a>, an irregular sea urchin (<a href="/wiki/Irregularia" title="Irregularia">Irregularia</a>)</div> </li> <li class="gallerybox" style="width: 136px"> <div class="thumb" style="width: 134px;"><span typeof="mw:File"><a href="/wiki/File:Phyllacanthus.jpg" class="mw-file-description" title="Phyllacanthus imperialis, a cidaroid sea urchin (Cidaroidea)"><img alt="Phyllacanthus imperialis, a cidaroid sea urchin (Cidaroidea)" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Phyllacanthus.jpg/201px-Phyllacanthus.jpg" decoding="async" width="134" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Phyllacanthus.jpg/302px-Phyllacanthus.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Phyllacanthus.jpg/402px-Phyllacanthus.jpg 2x" data-file-width="3112" data-file-height="2785" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Phyllacanthus_imperialis" title="Phyllacanthus imperialis">Phyllacanthus imperialis</a></i>, a cidaroid sea urchin (<a href="/wiki/Cidaroidea" class="mw-redirect" title="Cidaroidea">Cidaroidea</a>)</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="Description">Description</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=2" title="Edit section: Description"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Urchin9b.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/Urchin9b.jpg/330px-Urchin9b.jpg" decoding="async" width="330" height="222" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/Urchin9b.jpg/500px-Urchin9b.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/06/Urchin9b.jpg/660px-Urchin9b.jpg 2x" data-file-width="900" data-file-height="606" /></a><figcaption>Sea urchin anatomy based on <i><a href="/wiki/Arbacia" title="Arbacia">Arbacia</a></i> sp.</figcaption></figure> <p>Urchins typically range in size from 3 to 10 cm (1 to 4 in), but the largest species can reach up to 36 cm (14 in).<sup id="cite_ref-IZ_4-0" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> They have a rigid, usually spherical body bearing moveable spines, which give the <a href="/wiki/Class_(biology)" title="Class (biology)">class</a> the name <i>Echinoidea</i> (from the Greek <span lang="grc"><a href="https://en.wiktionary.org/wiki/%E1%BC%90%CF%87%E1%BF%96%CE%BD%CE%BF%CF%82#Ancient_Greek" class="extiw" title="wikt:ἐχῖνος">ἐχῖνος</a></span> <span title="Ancient Greek (to 1453)-language text"><i lang="grc-LA">ekhinos</i></span> 'spine').<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The name <i>urchin</i> is an old word for <a href="/wiki/Hedgehog" title="Hedgehog">hedgehog</a>, which sea urchins resemble; they have archaically been called <b>sea hedgehogs</b>.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The name is derived from the Old French <i lang="fro"><a href="https://en.wiktionary.org/wiki/herichun#Old_French" class="extiw" title="wikt:herichun">herichun</a></i>, from Latin <i lang="la"><a href="https://en.wiktionary.org/wiki/ericius#Latin" class="extiw" title="wikt:ericius">ericius</a></i> ('hedgehog').<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>Like other echinoderms, sea urchin early larvae have bilateral symmetry,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> but they develop five-fold symmetry as they mature. This is most apparent in the "regular" sea urchins, which have roughly spherical bodies with five equally sized parts radiating out from their central axes. The mouth is at the base of the animal and the anus at the top; the lower surface is described as "oral" and the upper surface as "aboral".<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ruppert_2-3" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Several sea urchins, however, including the sand dollars, are oval in shape, with distinct front and rear ends, giving them a degree of bilateral symmetry. In these urchins, the upper surface of the body is slightly domed, but the underside is flat, while the sides are devoid of tube feet. This "irregular" body form has evolved to allow the animals to burrow through sand or other soft materials.<sup id="cite_ref-IZ_4-1" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Systems">Systems</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=3" title="Edit section: Systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Musculoskeletal">Musculoskeletal</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=4" title="Edit section: Musculoskeletal"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Test_(biology)" title="Test (biology)">Test (biology)</a> and <a href="/wiki/Tube_feet" title="Tube feet">Tube feet</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Seeigel-Saugfuesse(Galicien2005).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Seeigel-Saugfuesse%28Galicien2005%29.jpg/250px-Seeigel-Saugfuesse%28Galicien2005%29.jpg" decoding="async" width="150" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Seeigel-Saugfuesse%28Galicien2005%29.jpg/330px-Seeigel-Saugfuesse%28Galicien2005%29.jpg 2x" data-file-width="616" data-file-height="616" /></a><figcaption><a href="/wiki/Tube_feet" title="Tube feet">Tube feet</a> of a <a href="/wiki/Strongylocentrotus_purpuratus" title="Strongylocentrotus purpuratus">purple sea urchin</a></figcaption></figure> <p>The internal organs are enclosed in a hard shell or test composed of fused plates of <a href="/wiki/Calcium_carbonate" title="Calcium carbonate">calcium carbonate</a> covered by a thin <a href="/wiki/Dermis" title="Dermis">dermis</a> and <a href="/wiki/Epidermis" title="Epidermis">epidermis</a>. The test is referred to as an <a href="/wiki/Endoskeleton" title="Endoskeleton">endoskeleton</a> rather than exoskeleton even though it encloses almost all of the urchin. This is because it is covered with a thin layer of muscle and skin; sea urchins also do not need to molt the way invertebrates with true exoskeletons do, instead the plates forming the test grow as the animal does. </p><p>The test is rigid, and divides into five ambulacral grooves separated by five wider interambulacral areas. Each of these ten longitudinal columns consists of two sets of plates (thus comprising 20 columns in total). The ambulacral plates have pairs of tiny holes through which the tube feet extend.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>All of the plates are covered in rounded tubercles to which the spines are attached. The spines are used for defence and for locomotion and come in a variety of forms.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> The inner surface of the test is lined by <a href="/wiki/Peritoneum" title="Peritoneum">peritoneum</a>.<sup id="cite_ref-IZ_4-2" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Sea urchins convert aqueous <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">carbon dioxide</a> using a <a href="/wiki/Catalytic" class="mw-redirect" title="Catalytic">catalytic</a> process involving <a href="/wiki/Nickel" title="Nickel">nickel</a> into the calcium carbonate portion of the test.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Ricci_di_mare_luminosi.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Ricci_di_mare_luminosi.jpg/220px-Ricci_di_mare_luminosi.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Ricci_di_mare_luminosi.jpg/330px-Ricci_di_mare_luminosi.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Ricci_di_mare_luminosi.jpg/440px-Ricci_di_mare_luminosi.jpg 2x" data-file-width="720" data-file-height="540" /></a><figcaption>Mediterranean sea urchins illuminated to reveal the mesodermal calcite structure.</figcaption></figure> <p>Most species have two series of spines, primary (long) and secondary (short), distributed over the surface of the body, with the shortest at the poles and the longest at the equator. The spines are usually hollow and cylindrical. Contraction of the muscular sheath that covers the test causes the spines to lean in one direction or another, while an inner sheath of collagen fibres can reversibly change from soft to rigid which can lock the spine in one position. Located among the spines are several types of <a href="/wiki/Pedicellaria" title="Pedicellaria">pedicellaria</a>, moveable stalked structures with jaws.<sup id="cite_ref-Ruppert_2-4" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins move by walking, using their many flexible tube feet in a way similar to that of starfish; regular sea urchins do not have any favourite walking direction.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> The tube feet protrude through pairs of pores in the test, and are operated by a <a href="/wiki/Water_vascular_system" title="Water vascular system">water vascular system</a>; this works through <a href="/wiki/Hydraulic_pressure" class="mw-redirect" title="Hydraulic pressure">hydraulic pressure</a>, allowing the sea urchin to pump water into and out of the tube feet. During locomotion, the tube feet are assisted by the spines which can be used for pushing the body along or to lift the test off the substrate. Movement is generally related to feeding, with the <a href="/wiki/Red_sea_urchin" title="Red sea urchin">red sea urchin</a> (<i>Mesocentrotus franciscanus</i>) managing about 7.5 cm (3 in) a day when there is ample food, and up to 50 cm (20 in) a day where there is not. An inverted sea urchin can right itself by progressively attaching and detaching its tube feet and manipulating its spines to roll its body upright.<sup id="cite_ref-Ruppert_2-5" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Some species bury themselves in soft sediment using their spines, and <i><a href="/wiki/Paracentrotus_lividus" title="Paracentrotus lividus">Paracentrotus lividus</a></i> uses its jaws to burrow into soft rocks.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-packed" style="text-align:center;"> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Sea_Urchin_test_5629_03_22.jpg" class="mw-file-description" title="Test of an Echinus esculentus, a regular sea urchin"><img alt="Test of an Echinus esculentus, a regular sea urchin" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Sea_Urchin_test_5629_03_22.jpg/250px-Sea_Urchin_test_5629_03_22.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Sea_Urchin_test_5629_03_22.jpg/500px-Sea_Urchin_test_5629_03_22.jpg 1.5x" data-file-width="3648" data-file-height="2736" /></a></span></div> <div class="gallerytext">Test of an <i><a href="/wiki/Echinus_esculentus" title="Echinus esculentus">Echinus esculentus</a></i>, a regular sea urchin</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:BlackSeaUrchinTest.jpg" class="mw-file-description" title="Test of black sea urchin, showing tubercles and ambulacral plates (on right)"><img alt="Test of black sea urchin, showing tubercles and ambulacral plates (on right)" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3c/BlackSeaUrchinTest.jpg/240px-BlackSeaUrchinTest.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3c/BlackSeaUrchinTest.jpg/360px-BlackSeaUrchinTest.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3c/BlackSeaUrchinTest.jpg/480px-BlackSeaUrchinTest.jpg 2x" data-file-width="3264" data-file-height="2448" /></a></span></div> <div class="gallerytext">Test of black sea urchin, showing tubercles and ambulacral plates (on right)</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Inner_surface_of_black_sea_urchin_test.jpg" class="mw-file-description" title="Inner surface of test, showing pentagonal interambulacral plates on right, and holes for tube feet on left."><img alt="Inner surface of test, showing pentagonal interambulacral plates on right, and holes for tube feet on left." src="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Inner_surface_of_black_sea_urchin_test.jpg/250px-Inner_surface_of_black_sea_urchin_test.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Inner_surface_of_black_sea_urchin_test.jpg/500px-Inner_surface_of_black_sea_urchin_test.jpg 1.5x" data-file-width="3264" data-file-height="2448" /></a></span></div> <div class="gallerytext">Inner surface of test, showing pentagonal interambulacral plates on right, and holes for tube feet on left.</div> </li> <li class="gallerybox" style="width: 142.66666666667px"> <div class="thumb" style="width: 140.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Echinodiscus2.jpg" class="mw-file-description" title="Test of an Echinodiscus tenuissimus, an irregular sea urchin ("sand dollar")"><img alt="Test of an Echinodiscus tenuissimus, an irregular sea urchin ("sand dollar")" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinodiscus2.jpg/211px-Echinodiscus2.jpg" decoding="async" width="141" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinodiscus2.jpg/316px-Echinodiscus2.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinodiscus2.jpg/421px-Echinodiscus2.jpg 2x" data-file-width="3124" data-file-height="2671" /></a></span></div> <div class="gallerytext">Test of an <i><a href="/wiki/Echinodiscus_tenuissimus" title="Echinodiscus tenuissimus">Echinodiscus tenuissimus</a></i>, an <a href="/wiki/Irregularia" title="Irregularia">irregular sea urchin</a> ("<a href="/wiki/Sand_dollar" title="Sand dollar">sand dollar</a>")</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Phyllacanthus_imperialis_test.JPG" class="mw-file-description" title="Test of a Phyllacanthus imperialis, a cidaroid sea urchin. These are characterised by their big tubercles, bearing large radiola."><img alt="Test of a Phyllacanthus imperialis, a cidaroid sea urchin. These are characterised by their big tubercles, bearing large radiola." src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Phyllacanthus_imperialis_test.JPG/240px-Phyllacanthus_imperialis_test.JPG" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Phyllacanthus_imperialis_test.JPG/359px-Phyllacanthus_imperialis_test.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Phyllacanthus_imperialis_test.JPG/479px-Phyllacanthus_imperialis_test.JPG 2x" data-file-width="3702" data-file-height="2782" /></a></span></div> <div class="gallerytext">Test of a <i><a href="/wiki/Phyllacanthus_imperialis" title="Phyllacanthus imperialis">Phyllacanthus imperialis</a></i>, a <a href="/wiki/Cidaroida" title="Cidaroida">cidaroid</a> sea urchin. These are characterised by their big tubercles, bearing large radiola.</div> </li> <li class="gallerybox" style="width: 202px"> <div class="thumb" style="width: 200px;"><span typeof="mw:File"><a href="/wiki/File:Sea_urchin_shell_-_pattern_(6658690371).jpg" class="mw-file-description" title="Close-up of the test showing an ambulacral groove with its two rows of pore-pairs, between two interambulacra areas (green). The tubercles are non-perforated."><img alt="Close-up of the test showing an ambulacral groove with its two rows of pore-pairs, between two interambulacra areas (green). The tubercles are non-perforated." src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sea_urchin_shell_-_pattern_%286658690371%29.jpg/330px-Sea_urchin_shell_-_pattern_%286658690371%29.jpg" decoding="async" width="200" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sea_urchin_shell_-_pattern_%286658690371%29.jpg/500px-Sea_urchin_shell_-_pattern_%286658690371%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Sea_urchin_shell_-_pattern_%286658690371%29.jpg/960px-Sea_urchin_shell_-_pattern_%286658690371%29.jpg 2x" data-file-width="1482" data-file-height="890" /></a></span></div> <div class="gallerytext">Close-up of the test showing an ambulacral groove with its two rows of pore-pairs, between two interambulacra areas (green). The tubercles are non-perforated.</div> </li> <li class="gallerybox" style="width: 182px"> <div class="thumb" style="width: 180px;"><span typeof="mw:File"><a href="/wiki/File:Sea_Urchin_Shell_detail.jpg" class="mw-file-description" title="Close-up of a cidaroid sea urchin apical disc: the 5 holes are the gonopores, and the central one is the anus ("periproct"). The biggest genital plate is the madreporite.[15]"><img alt="Close-up of a cidaroid sea urchin apical disc: the 5 holes are the gonopores, and the central one is the anus ("periproct"). The biggest genital plate is the madreporite.[15]" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Sea_Urchin_Shell_detail.jpg/270px-Sea_Urchin_Shell_detail.jpg" decoding="async" width="180" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Sea_Urchin_Shell_detail.jpg/405px-Sea_Urchin_Shell_detail.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Sea_Urchin_Shell_detail.jpg/540px-Sea_Urchin_Shell_detail.jpg 2x" data-file-width="5184" data-file-height="3456" /></a></span></div> <div class="gallerytext">Close-up of a cidaroid sea urchin apical disc: the 5 holes are the gonopores, and the central one is the anus ("periproct"). The biggest genital plate is the <a href="/wiki/Madreporite" title="Madreporite">madreporite</a>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></div> </li> </ul> <div class="mw-heading mw-heading3"><h3 id="Feeding_and_digestion">Feeding and digestion</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=5" title="Edit section: Feeding and digestion"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Seeigel_Gebiss.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/46/Seeigel_Gebiss.jpg/250px-Seeigel_Gebiss.jpg" decoding="async" width="220" height="124" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/46/Seeigel_Gebiss.jpg/330px-Seeigel_Gebiss.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/46/Seeigel_Gebiss.jpg/500px-Seeigel_Gebiss.jpg 2x" data-file-width="3000" data-file-height="1686" /></a><figcaption>Dentition of a sea urchin</figcaption></figure> <p>The mouth lies in the centre of the oral surface in regular urchins, or towards one end in irregular urchins. It is surrounded by lips of softer tissue, with numerous small, embedded bony pieces. This area, called the peristome, also includes five pairs of modified tube feet and, in many species, five pairs of gills.<sup id="cite_ref-IZ_4-3" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> The jaw apparatus consists of five strong arrow-shaped plates known as pyramids, the ventral surface of each of which has a toothband with a hard tooth pointing towards the centre of the mouth. Specialised muscles control the protrusion of the apparatus and the action of the teeth, and the animal can grasp, scrape, pull and tear.<sup id="cite_ref-Ruppert_2-6" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The structure of the mouth and teeth have been found to be so efficient at grasping and grinding that similar structures have been tested for use in mechanical applications.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p><p>On the upper surface of the test at the aboral pole is a membrane, the <a href="/wiki/Periproct" title="Periproct">periproct</a>, which surrounds the <a href="/wiki/Anus" title="Anus">anus</a>. The periproct contains a variable number of hard plates, five of which, the genital plates, contain the gonopores, and one is modified to contain the <a href="/wiki/Madreporite" title="Madreporite">madreporite</a>, which is used to balance the water vascular system.<sup id="cite_ref-Ruppert_2-7" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Lanterne_d%27Aristote.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Lanterne_d%27Aristote.jpg/220px-Lanterne_d%27Aristote.jpg" decoding="async" width="220" height="166" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Lanterne_d%27Aristote.jpg/330px-Lanterne_d%27Aristote.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Lanterne_d%27Aristote.jpg/440px-Lanterne_d%27Aristote.jpg 2x" data-file-width="1200" data-file-height="903" /></a><figcaption>Aristotle's lantern in a sea urchin, viewed in lateral section</figcaption></figure> <p>The mouth of most sea urchins is made up of five calcium carbonate teeth or plates, with a fleshy, tongue-like structure within. The entire chewing organ is known as Aristotle's lantern from <a href="/wiki/Aristotle" title="Aristotle">Aristotle</a>'s description in his <i><a href="/wiki/History_of_Animals" title="History of Animals">History of Animals</a></i> (translated by <a href="/wiki/D%27Arcy_Thompson" class="mw-redirect" title="D'Arcy Thompson">D'Arcy Thompson</a>): </p> <style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote"><p>... the urchin has what we mainly call its head and mouth down below, and a place for the issue of the residuum up above. The urchin has, also, five hollow teeth inside, and in the middle of these teeth a fleshy substance serving the office of a <a href="/wiki/Tongue" title="Tongue">tongue</a>. Next to this comes the <a href="/wiki/Esophagus" title="Esophagus">esophagus</a>, and then the <a href="/wiki/Stomach" title="Stomach">stomach</a>, divided into five parts, and filled with excretion, all the five parts uniting at the <a href="/wiki/Anus" title="Anus">anal</a> vent, where the shell is perforated for an outlet ... In reality the mouth-apparatus of the urchin is continuous from one end to the other, but to outward appearance it is not so, but looks like a horn <a href="/wiki/Lantern" title="Lantern">lantern</a> with the panes of horn left out.</p></blockquote> <p>However, this has recently been proven to be a mistranslation. Aristotle's lantern is actually referring to the whole shape of sea urchins, which look like the ancient lamps of Aristotle's time.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Heart_urchin" class="mw-redirect" title="Heart urchin">Heart urchins</a> are unusual in not having a lantern. Instead, the mouth is surrounded by <a href="/wiki/Cilia" class="mw-redirect" title="Cilia">cilia</a> that pull strings of mucus containing food particles towards a series of grooves around the mouth.<sup id="cite_ref-IZ_4-4" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Echinoidea_anatomie.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinoidea_anatomie.svg/250px-Echinoidea_anatomie.svg.png" decoding="async" width="240" height="184" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinoidea_anatomie.svg/360px-Echinoidea_anatomie.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Echinoidea_anatomie.svg/480px-Echinoidea_anatomie.svg.png 2x" data-file-width="340" data-file-height="260" /></a><figcaption>Digestive and circulatory systems of a regular sea urchin:<br />a = <a href="/wiki/Anus" title="Anus">anus</a>; m = <a href="/wiki/Madreporite" title="Madreporite">madreporite</a>; s = aquifer canal; r = radial canal; p = podial ampulla; k = test wall; i = <a href="/wiki/Intestine" class="mw-redirect" title="Intestine">intestine</a>; b = mouth</figcaption></figure> <p>The lantern, where present, surrounds both the mouth cavity and the <a href="/wiki/Pharynx" title="Pharynx">pharynx</a>. At the top of the lantern, the pharynx opens into the esophagus, which runs back down the outside of the lantern, to join the small <a href="/wiki/Intestine" class="mw-redirect" title="Intestine">intestine</a> and a single <a href="/wiki/Caecum" class="mw-redirect" title="Caecum">caecum</a>. The small intestine runs in a full circle around the inside of the test, before joining the large intestine, which completes another circuit in the opposite direction. From the large intestine, a <a href="/wiki/Rectum" title="Rectum">rectum</a> ascends towards the anus. Despite the names, the small and large intestines of sea urchins are in no way <a href="/wiki/Homology_(biology)" title="Homology (biology)">homologous</a> to the similarly named structures in vertebrates.<sup id="cite_ref-IZ_4-5" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Digestion occurs in the intestine, with the caecum producing further digestive <a href="/wiki/Enzyme" title="Enzyme">enzymes</a>. An additional tube, called the siphon, runs beside much of the intestine, opening into it at both ends. It may be involved in resorption of water from food.<sup id="cite_ref-IZ_4-6" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Circulation_and_respiration">Circulation and respiration</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=6" title="Edit section: Circulation and respiration"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Diadema_setosum_(Kenya).JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Diadema_setosum_%28Kenya%29.JPG/220px-Diadema_setosum_%28Kenya%29.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Diadema_setosum_%28Kenya%29.JPG/330px-Diadema_setosum_%28Kenya%29.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Diadema_setosum_%28Kenya%29.JPG/440px-Diadema_setosum_%28Kenya%29.JPG 2x" data-file-width="3223" data-file-height="2418" /></a><figcaption><i><a href="/wiki/Diadema_setosum" title="Diadema setosum">Diadema setosum</a></i></figcaption></figure> <p>The water vascular system leads downwards from the madreporite through the slender stone canal to the ring canal, which encircles the oesophagus. Radial canals lead from here through each ambulacral area to terminate in a small tentacle that passes through the ambulacral plate near the aboral pole. Lateral canals lead from these radial canals, ending in ampullae. From here, two tubes pass through a pair of pores on the plate to terminate in the tube feet.<sup id="cite_ref-Ruppert_2-8" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins possess a hemal system with a complex network of vessels in the mesenteries around the gut, but little is known of the functioning of this system.<sup id="cite_ref-Ruppert_2-9" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> However, the main circulatory fluid fills the general body cavity, or <a href="/wiki/Coelom" title="Coelom">coelom</a>. This coelomic fluid contains <a href="/wiki/Phagocyte" title="Phagocyte">phagocytic</a> coelomocytes, which move through the vascular and hemal systems and are involved in internal transport and gas exchange. The coelomocytes are an essential part of <a href="/wiki/Blood_clotting" class="mw-redirect" title="Blood clotting">blood clotting</a>, but also collect waste products and actively remove them from the body through the gills and tube feet.<sup id="cite_ref-IZ_4-7" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Most sea urchins possess five pairs of external gills attached to the peristomial membrane around their mouths. These thin-walled projections of the body cavity are the main organs of respiration in those urchins that possess them. Fluid can be pumped through the gills' interiors by muscles associated with the lantern, but this does not provide a continuous flow, and occurs only when the animal is low in oxygen. Tube feet can also act as respiratory organs, and are the primary sites of gas exchange in heart urchins and sand dollars, both of which lack gills. The inside of each tube foot is divided by a septum which reduces diffusion between the incoming and outgoing streams of fluid.<sup id="cite_ref-Ruppert_2-10" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Nervous_system_and_senses">Nervous system and senses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=7" title="Edit section: Nervous system and senses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The nervous system of sea urchins has a relatively simple layout. With no true brain, the neural center is a large nerve ring encircling the mouth just inside the lantern. From the nerve ring, five nerves radiate underneath the radial canals of the water vascular system, and branch into numerous finer nerves to innervate the tube feet, spines, and <a href="/wiki/Pedicellariae" class="mw-redirect" title="Pedicellariae">pedicellariae</a>.<sup id="cite_ref-IZ_4-8" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins are sensitive to touch, light, and chemicals. There are numerous sensitive cells in the epithelium, especially in the spines, pedicellaria and tube feet, and around the mouth.<sup id="cite_ref-Ruppert_2-11" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Although they do not have eyes or eye spots (except for <a href="/wiki/Diadematidae" title="Diadematidae">diadematids</a>, which can follow a threat with their spines), the entire body of most regular sea urchins might function as a compound eye.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> In general, sea urchins are negatively attracted to light, and seek to hide themselves in crevices or under objects. Most species, apart from <a href="/wiki/Cidaris" title="Cidaris">pencil urchins</a>, have <a href="/wiki/Statocyst" title="Statocyst">statocysts</a> in globular organs called spheridia. These are stalked structures and are located within the ambulacral areas; their function is to help in gravitational orientation.<sup id="cite_ref-IZ_4-9" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Life_history">Life history</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=8" title="Edit section: Life history"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Reproduction">Reproduction</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=9" title="Edit section: Reproduction"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><span><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/8/84/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv/220px--Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="165" data-durationhint="20" data-mwtitle="Male_Flower_Sea_Urchin_(toxopneustes_roseus).theora.ogv" data-mwprovider="wikimediacommons" resource="/wiki/File:Male_Flower_Sea_Urchin_(toxopneustes_roseus).theora.ogv"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/8/84/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/8/84/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/8/84/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv" type="video/ogg; codecs="theora"" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/8/84/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv/Male_Flower_Sea_Urchin_%28toxopneustes_roseus%29.theora.ogv.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="192" data-height="144" /></video></span><figcaption>Male flower urchin (<i><a href="/wiki/Toxopneustes_roseus" title="Toxopneustes roseus">Toxopneustes roseus</a></i>) releasing milt, November 1, 2011, Lalo Cove, Sea of Cortez</figcaption></figure> <p>Sea urchins are <a href="/wiki/Dioecious" class="mw-redirect" title="Dioecious">dioecious</a>, having separate male and female sexes, although no distinguishing features are visible externally. In addition to their role in reproduction, the <a href="/wiki/Gonad" title="Gonad">gonads</a> are also nutrient storing organs, and are made up of two main type of cells: <a href="/wiki/Germ_cell" title="Germ cell">germ cells</a>, and <a href="/wiki/Somatic_cell" title="Somatic cell">somatic cells</a> called nutritive phagocytes.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> Regular sea urchins have five gonads, lying underneath the interambulacral regions of the test, while the irregular forms mostly have four, with the hindmost gonad being absent; heart urchins have three or two. Each gonad has a single duct rising from the upper pole to open at a <a href="/wiki/Gonopore" title="Gonopore">gonopore</a> lying in one of the genital plates surrounding the anus. Some burrowing sand dollars have an elongated papilla that enables the liberation of gametes above the surface of the sediment.<sup id="cite_ref-Ruppert_2-12" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The gonads are lined with muscles underneath the peritoneum, and these allow the animal to squeeze its <a href="/wiki/Gamete" title="Gamete">gametes</a> through the duct and into the surrounding sea water, where <a href="/wiki/Fertilization" class="mw-redirect" title="Fertilization">fertilization</a> takes place.<sup id="cite_ref-IZ_4-10" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Development">Development</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=10" title="Edit section: Development"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Sea_Urchin_Blastula.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Sea_Urchin_Blastula.jpg/220px-Sea_Urchin_Blastula.jpg" decoding="async" width="220" height="195" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Sea_Urchin_Blastula.jpg/330px-Sea_Urchin_Blastula.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Sea_Urchin_Blastula.jpg/440px-Sea_Urchin_Blastula.jpg 2x" data-file-width="762" data-file-height="676" /></a><figcaption>Sea urchin blastula</figcaption></figure> <p>During early development, the sea urchin <a href="/wiki/Embryo" title="Embryo">embryo</a> undergoes 10 cycles of <a href="/wiki/Cell_division" title="Cell division">cell division</a>,<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> resulting in a single <a href="/wiki/Epithelial" class="mw-redirect" title="Epithelial">epithelial</a> layer enveloping the <a href="/wiki/Blastocoel" title="Blastocoel">blastocoel</a>. The embryo then begins <a href="/wiki/Gastrulation" title="Gastrulation">gastrulation</a>, a multipart process which dramatically rearranges its structure by <a href="/wiki/Invagination" title="Invagination">invagination</a> to produce the three <a href="/wiki/Germ_layer" title="Germ layer">germ layers</a>, involving an <a href="/wiki/Epithelial-mesenchymal_transition" class="mw-redirect" title="Epithelial-mesenchymal transition">epithelial-mesenchymal transition</a>; primary <a href="/wiki/Mesenchyme" title="Mesenchyme">mesenchyme</a> cells move into the blastocoel<sup id="cite_ref-pmid15367199_23-0" class="reference"><a href="#cite_note-pmid15367199-23"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> and become <a href="/wiki/Mesoderm" title="Mesoderm">mesoderm</a>.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> It has been suggested that <a href="/wiki/Epithelial_polarity" title="Epithelial polarity">epithelial polarity</a> together with planar cell polarity might be sufficient to drive gastrulation in sea urchins.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-center" typeof="mw:File/Thumb"><a href="/wiki/File:Left-right_asymmetry_in_the_sea_urchin_-_journal.pbio.1001404.g001.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Left-right_asymmetry_in_the_sea_urchin_-_journal.pbio.1001404.g001.png/960px-Left-right_asymmetry_in_the_sea_urchin_-_journal.pbio.1001404.g001.png" decoding="async" width="590" height="170" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Left-right_asymmetry_in_the_sea_urchin_-_journal.pbio.1001404.g001.png/1180px-Left-right_asymmetry_in_the_sea_urchin_-_journal.pbio.1001404.g001.png 2x" data-file-width="1459" data-file-height="420" /></a><figcaption>The development of a regular sea urchin</figcaption></figure> <p>An unusual feature of sea urchin development is the replacement of the larva's <a href="/wiki/Bilateral_symmetry" class="mw-redirect" title="Bilateral symmetry">bilateral symmetry</a> by the adult's broadly fivefold symmetry. During cleavage, mesoderm and small micromeres are specified. At the end of gastrulation, cells of these two types form <a href="/wiki/Coelom" title="Coelom">coelomic</a> pouches. In the larval stages, the adult rudiment grows from the left coelomic pouch; after metamorphosis, that rudiment grows to become the adult. The <a href="/wiki/Animal-vegetal_axis" class="mw-redirect" title="Animal-vegetal axis">animal-vegetal axis</a> is established before the egg is fertilized. The oral-aboral axis is specified early in cleavage, and the left-right axis appears at the late gastrula stage.<sup id="cite_ref-WarnerLyons2012_26-0" class="reference"><a href="#cite_note-WarnerLyons2012-26"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Life_cycle_and_development">Life cycle and development</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=11" title="Edit section: Life cycle and development"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Echinocardium_cordatum_(Pennant,_1777)_early_pluteus_width_ca.JPEG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG/130px-Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG" decoding="async" width="130" height="178" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG/195px-Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG/260px-Echinocardium_cordatum_%28Pennant%2C_1777%29_early_pluteus_width_ca.JPEG 2x" data-file-width="328" data-file-height="449" /></a><figcaption><i>Pluteus</i> larva has <a href="/wiki/Bilateral_symmetry" class="mw-redirect" title="Bilateral symmetry">bilateral symmetry</a>.</figcaption></figure> <p>In most cases, the female's eggs float freely in the sea, but some species hold onto them with their spines, affording them a greater degree of protection. The unfertilized egg meets with the free-floating sperm released by males, and develops into a free-swimming <a href="/wiki/Blastula" class="mw-redirect" title="Blastula">blastula</a> embryo in as few as 12 hours. Initially a simple ball of cells, the blastula soon <a href="/wiki/Gastrulation" title="Gastrulation">transforms</a> into a cone-shaped <b>echinopluteus</b> larva. In most species, this larva has 12 elongated arms lined with bands of cilia that capture food particles and transport them to the mouth. In a few species, the blastula contains supplies of nutrient <a href="/wiki/Yolk" title="Yolk">yolk</a> and lacks arms, since it has no need to feed.<sup id="cite_ref-IZ_4-11" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Several months are needed for the larva to complete its development, the change into the adult form beginning with the formation of test plates in a juvenile rudiment which develops on the left side of the larva, its axis being perpendicular to that of the larva. Soon, the larva sinks to the bottom and <a href="/wiki/Metamorphosis" title="Metamorphosis">metamorphoses</a> into a juvenile urchin in as little as one hour.<sup id="cite_ref-Ruppert_2-13" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> In some species, adults reach their maximum size in about five years.<sup id="cite_ref-IZ_4-12" class="reference"><a href="#cite_note-IZ-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Purple_urchin" class="mw-redirect" title="Purple urchin">purple urchin</a> becomes sexually mature in two years and may live for twenty.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Longevity">Longevity</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=12" title="Edit section: Longevity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Red_sea_urchin" title="Red sea urchin">Red sea urchins</a> were originally thought to live 7 to 10 years but recent studies have shown that they can live for more than 100 years. Canadian red urchins have been found to be around 200 years old.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ebert_2003_29-0" class="reference"><a href="#cite_note-Ebert_2003-29"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Ecology">Ecology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=13" title="Edit section: Ecology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Trophic_level">Trophic level</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=14" title="Edit section: Trophic level"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><span><video id="mwe_player_1" poster="//upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Sea_Urchin.theora.ogv/220px--Sea_Urchin.theora.ogv.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="165" data-durationhint="6" data-mwtitle="Sea_Urchin.theora.ogv" data-mwprovider="wikimediacommons" resource="/wiki/File:Sea_Urchin.theora.ogv"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/bf/Sea_Urchin.theora.ogv/Sea_Urchin.theora.ogv.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/bf/Sea_Urchin.theora.ogv/Sea_Urchin.theora.ogv.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/b/bf/Sea_Urchin.theora.ogv" type="video/ogg; codecs="theora"" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/bf/Sea_Urchin.theora.ogv/Sea_Urchin.theora.ogv.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="192" data-height="144" /></video></span><figcaption>Sea urchin in natural habitat</figcaption></figure> <p>Sea urchins feed mainly on <a href="/wiki/Algae" title="Algae">algae</a>, so they are primarily <a href="/wiki/Herbivore" title="Herbivore">herbivores</a>, but can feed on sea cucumbers and a wide range of invertebrates, such as <a href="/wiki/Mussel" title="Mussel">mussels</a>, <a href="/wiki/Polychaete" title="Polychaete">polychaetes</a>, <a href="/wiki/Sponge" title="Sponge">sponges</a>, brittle stars, and crinoids, making them omnivores, consumers at a range of <a href="/wiki/Trophic_level" title="Trophic level">trophic levels</a>.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Predators,_parasites,_and_diseases"><span id="Predators.2C_parasites.2C_and_diseases"></span>Predators, parasites, and diseases</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=15" title="Edit section: Predators, parasites, and diseases"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Mass mortality of sea urchins was first reported in the 1970s, but diseases in sea urchins had been little studied before the advent of aquaculture. In 1981, bacterial "spotting disease" caused almost complete mortality in juvenile <i><a href="/wiki/Pseudocentrotus_depressus" title="Pseudocentrotus depressus">Pseudocentrotus depressus</a></i> and <i><a href="/wiki/Hemicentrotus_pulcherrimus" class="mw-redirect" title="Hemicentrotus pulcherrimus">Hemicentrotus pulcherrimus</a></i>, both cultivated in Japan; the disease recurred in succeeding years. It was divided into a cool-water "spring" disease and a hot-water "summer" form.<sup id="cite_ref-Lawrence_31-0" class="reference"><a href="#cite_note-Lawrence-31"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Another condition, <a href="/wiki/Bald_sea_urchin_disease" title="Bald sea urchin disease">bald sea urchin disease</a>, causes loss of spines and skin lesions and is believed to be bacterial in origin.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>Adult sea urchins are usually well protected against most predators by their strong and sharp spines, which can be venomous in some species.<sup id="cite_ref-Defence_–_spines_33-0" class="reference"><a href="#cite_note-Defence_–_spines-33"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> The small <a href="/wiki/Diademichthys_lineatus" title="Diademichthys lineatus">urchin clingfish</a> lives among the spines of urchins such as <i><a href="/wiki/Diadema_(sea_urchin)" title="Diadema (sea urchin)">Diadema</a></i>; juveniles feed on the pedicellariae and sphaeridia, adult males choose the tube feet and adult females move away to feed on shrimp eggs and molluscs.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins are one of the favourite foods of many <a href="/wiki/Lobster" title="Lobster">lobsters</a>, <a href="/wiki/Crab" title="Crab">crabs</a>, <a href="/wiki/Triggerfish" title="Triggerfish">triggerfish</a>, <a href="/wiki/California_sheephead" title="California sheephead">California sheephead</a>, <a href="/wiki/Sea_otter" title="Sea otter">sea otter</a> and <a href="/wiki/Anarhichadidae" title="Anarhichadidae">wolf eels</a> (which specialise in sea urchins). All these animals carry particular adaptations (teeth, pincers, claws) and a strength that allow them to overcome the excellent protective features of sea urchins. Left unchecked by predators, urchins devastate their environments, creating what biologists call an <a href="/wiki/Urchin_barren" title="Urchin barren">urchin barren</a>, devoid of macroalgae and associated <a href="/wiki/Fauna" title="Fauna">fauna</a>.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> Sea urchins graze on the lower stems of kelp, causing the kelp to drift away and die. Loss of the habitat and nutrients provided by <a href="/wiki/Kelp_forest" title="Kelp forest">kelp forests</a> leads to profound <a href="/wiki/Cascade_effect_(ecology)" title="Cascade effect (ecology)">cascade effects</a> on the marine ecosystem. Sea otters have re-entered <a href="/wiki/British_Columbia" title="British Columbia">British Columbia</a>, dramatically improving coastal ecosystem health.<sup id="cite_ref-dfo_36-0" class="reference"><a href="#cite_note-dfo-36"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-packed" style="text-align:center;"> <li class="gallerybox" style="width: 82px"> <div class="thumb" style="width: 80px;"><span typeof="mw:File"><a href="/wiki/File:Wolf_eel_eating_a_sea_urchin.jpg" class="mw-file-description" title="Wolf eel, a highly specialized predator of sea urchins"><img alt="Wolf eel, a highly specialized predator of sea urchins" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Wolf_eel_eating_a_sea_urchin.jpg/120px-Wolf_eel_eating_a_sea_urchin.jpg" decoding="async" width="80" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Wolf_eel_eating_a_sea_urchin.jpg/180px-Wolf_eel_eating_a_sea_urchin.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Wolf_eel_eating_a_sea_urchin.jpg/240px-Wolf_eel_eating_a_sea_urchin.jpg 2x" data-file-width="2108" data-file-height="3162" /></a></span></div> <div class="gallerytext"><a href="/wiki/Wolf_eel" title="Wolf eel">Wolf eel</a>, a highly specialized predator of sea urchins</div> </li> <li class="gallerybox" style="width: 122px"> <div class="thumb" style="width: 120px;"><span typeof="mw:File"><a href="/wiki/File:Sea_otter_with_sea_urchin.jpg" class="mw-file-description" title="A sea otter feeding on a purple sea urchin."><img alt="A sea otter feeding on a purple sea urchin." src="//upload.wikimedia.org/wikipedia/commons/thumb/2/25/Sea_otter_with_sea_urchin.jpg/250px-Sea_otter_with_sea_urchin.jpg" decoding="async" width="120" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/25/Sea_otter_with_sea_urchin.jpg/330px-Sea_otter_with_sea_urchin.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/25/Sea_otter_with_sea_urchin.jpg/500px-Sea_otter_with_sea_urchin.jpg 2x" data-file-width="1650" data-file-height="1650" /></a></span></div> <div class="gallerytext">A <a href="/wiki/Sea_otter" title="Sea otter">sea otter</a> feeding on a <a href="/wiki/Strongylocentrotus_purpuratus" title="Strongylocentrotus purpuratus">purple sea urchin</a>.</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg" class="mw-file-description" title="A marbled stone crab (Carpilius convexus) attacking a slate pencil sea urchin (Heterocentrotus mamillatus)"><img alt="A marbled stone crab (Carpilius convexus) attacking a slate pencil sea urchin (Heterocentrotus mamillatus)" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/56/Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg/240px-Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/56/Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg/360px-Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/56/Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg/480px-Carpilius_convexus_is_consuming_Heterocentrotus_trigonarius_in_Hawaii.jpg 2x" data-file-width="3072" data-file-height="2304" /></a></span></div> <div class="gallerytext">A marbled stone crab (<i><a href="/wiki/Carpilius_convexus" title="Carpilius convexus">Carpilius convexus</a></i>) attacking a slate pencil sea urchin (<i><a href="/wiki/Heterocentrotus_mamillatus" title="Heterocentrotus mamillatus">Heterocentrotus mamillatus</a></i>)</div> </li> <li class="gallerybox" style="width: 132.66666666667px"> <div class="thumb" style="width: 130.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg" class="mw-file-description" title="A wrasse finishing the remains of a damaged Tripneustes gratilla"><img alt="A wrasse finishing the remains of a damaged Tripneustes gratilla" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg/196px-Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg" decoding="async" width="131" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg/294px-Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/97/Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg/393px-Saddle_Wrasse_are_feeding_on_sea_urchin_in_Kona.jpg 2x" data-file-width="2000" data-file-height="1834" /></a></span></div> <div class="gallerytext">A <a href="/wiki/Thalassoma_duperrey" class="mw-redirect" title="Thalassoma duperrey">wrasse</a> finishing the remains of a damaged <i><a href="/wiki/Tripneustes_gratilla" title="Tripneustes gratilla">Tripneustes gratilla</a></i></div> </li> </ul> <div class="mw-heading mw-heading3"><h3 id="Anti-predator_defences">Anti-predator defences</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=16" title="Edit section: Anti-predator defences"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Flower_urchin_by_Vincent_C_Chen.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Flower_urchin_by_Vincent_C_Chen.jpg/250px-Flower_urchin_by_Vincent_C_Chen.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Flower_urchin_by_Vincent_C_Chen.jpg/330px-Flower_urchin_by_Vincent_C_Chen.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/28/Flower_urchin_by_Vincent_C_Chen.jpg/500px-Flower_urchin_by_Vincent_C_Chen.jpg 2x" data-file-width="1024" data-file-height="768" /></a><figcaption>The <a href="/wiki/Flower_urchin" class="mw-redirect" title="Flower urchin">flower urchin</a> is a dangerous, potentially lethally venomous species.</figcaption></figure> <p>The <a href="/wiki/Spine_(zoology)" title="Spine (zoology)">spines</a>, long and sharp in some species, protect the urchin from <a href="/wiki/Predator" class="mw-redirect" title="Predator">predators</a>. Some tropical sea urchins like <a href="/wiki/Diadematidae" title="Diadematidae">Diadematidae</a>, <a href="/wiki/Echinothuriidae" title="Echinothuriidae">Echinothuriidae</a> and <a href="/wiki/Toxopneustidae" title="Toxopneustidae">Toxopneustidae</a> have venomous spines. Other creatures also make use of these defences; crabs, shrimps and other organisms shelter among the spines, and often adopt the colouring of their host. Some crabs in the <a href="/wiki/Dorippidae" title="Dorippidae">Dorippidae</a> family carry sea urchins, starfish, sharp shells or other protective objects in their claws.<sup id="cite_ref-Thiel_37-0" class="reference"><a href="#cite_note-Thiel-37"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Pedicellaria" title="Pedicellaria">Pedicellariae</a><sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> are a good means of defense against ectoparasites, but not a panacea as some of them actually feed on it.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> The hemal system defends against endoparasites.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Range_and_habitat">Range and habitat</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=17" title="Edit section: Range and habitat"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sea urchins are established in most seabed habitats from the intertidal downwards, at an extremely wide range of depths.<sup id="cite_ref-Kroh2010_41-0" class="reference"><a href="#cite_note-Kroh2010-41"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> Some species, such as <i><a href="/wiki/Cidaris" title="Cidaris">Cidaris</a> abyssicola</i>, can live at depths of several kilometres. Many genera are found in only the <a href="/wiki/Abyssal_zone" title="Abyssal zone">abyssal zone</a>, including many <a href="/wiki/Cidaroida" title="Cidaroida">cidaroids</a>, most of the genera in the <a href="/wiki/Echinothuriidae" title="Echinothuriidae">Echinothuriidae</a> family, and the "cactus urchins" <i><a href="/wiki/Dermechinus" title="Dermechinus">Dermechinus</a></i>. One of the deepest-living families is the <a href="/wiki/Pourtalesiidae" title="Pourtalesiidae">Pourtalesiidae</a>,<sup id="cite_ref-Pourtalesiidae_42-0" class="reference"><a href="#cite_note-Pourtalesiidae-42"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> strange bottle-shaped irregular sea urchins that live in only the <a href="/wiki/Hadal_zone" title="Hadal zone">hadal zone</a> and have been collected as deep as 6850 metres beneath the surface in the <a href="/wiki/Sunda_Trench" title="Sunda Trench">Sunda Trench</a>.<sup id="cite_ref-MahDeepest_43-0" class="reference"><a href="#cite_note-MahDeepest-43"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> Nevertheless, this makes sea urchin the class of echinoderms living the least deep, compared to <a href="/wiki/Brittle_star" title="Brittle star">brittle stars</a>, <a href="/wiki/Starfish" title="Starfish">starfish</a> and <a href="/wiki/Crinoid" title="Crinoid">crinoids</a> that remain abundant below 8,000 m (26,250 ft) and <a href="/wiki/Sea_cucumber" title="Sea cucumber">sea cucumbers</a> which have been recorded from 10,687 m (35,100 ft).<sup id="cite_ref-MahDeepest_43-1" class="reference"><a href="#cite_note-MahDeepest-43"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> </p><p>Population densities vary by habitat, with more dense populations in barren areas as compared to <a href="/wiki/Kelp" title="Kelp">kelp</a> stands.<sup id="cite_ref-Mattison1977_44-0" class="reference"><a href="#cite_note-Mattison1977-44"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Konar2000_45-0" class="reference"><a href="#cite_note-Konar2000-45"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> Even in these barren areas, greatest densities are found in shallow water. Populations are generally found in deeper water if wave action is present.<sup id="cite_ref-Konar2000_45-1" class="reference"><a href="#cite_note-Konar2000-45"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> Densities decrease in winter when storms cause them to seek protection in cracks and around larger underwater structures.<sup id="cite_ref-Konar2000_45-2" class="reference"><a href="#cite_note-Konar2000-45"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Shingle_urchin" class="mw-redirect" title="Shingle urchin">shingle urchin</a> (<i>Colobocentrotus atratus</i>), which lives on exposed shorelines, is particularly resistant to wave action. It is one of the few sea urchin that can survive many hours out of water.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins can be found in all climates, from warm seas to polar oceans.<sup id="cite_ref-Kroh2010_41-1" class="reference"><a href="#cite_note-Kroh2010-41"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> The larvae of the polar sea urchin <i><a href="/wiki/Sterechinus_neumayeri" title="Sterechinus neumayeri">Sterechinus neumayeri</a></i> have been found to use energy in metabolic processes twenty-five times more efficiently than do most other organisms.<sup id="cite_ref-UD_47-0" class="reference"><a href="#cite_note-UD-47"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> Despite their presence in nearly all the marine ecosystems, most species are found on temperate and tropical coasts, between the surface and some tens of meters deep, close to <a href="/wiki/Photosynthetic" class="mw-redirect" title="Photosynthetic">photosynthetic</a> food sources.<sup id="cite_ref-Kroh2010_41-2" class="reference"><a href="#cite_note-Kroh2010-41"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-packed" style="text-align:center;"> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Sea_urchins_in_california_tide_pools.jpg" class="mw-file-description" title="Purple sea urchins at low tide in California. They dig a cavity in the rock to hide from predators during the day."><img alt="Purple sea urchins at low tide in California. They dig a cavity in the rock to hide from predators during the day." src="//upload.wikimedia.org/wikipedia/commons/thumb/9/92/Sea_urchins_in_california_tide_pools.jpg/240px-Sea_urchins_in_california_tide_pools.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/92/Sea_urchins_in_california_tide_pools.jpg/360px-Sea_urchins_in_california_tide_pools.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/92/Sea_urchins_in_california_tide_pools.jpg/480px-Sea_urchins_in_california_tide_pools.jpg 2x" data-file-width="3072" data-file-height="2304" /></a></span></div> <div class="gallerytext"><a href="/wiki/Strongylocentrotus_purpuratus" title="Strongylocentrotus purpuratus">Purple sea urchins</a> at low tide in <a href="/wiki/California" title="California">California</a>. They dig a cavity in the rock to hide from predators during the day.</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Expl1825_-_Flickr_-_NOAA_Photo_Library.jpg" class="mw-file-description" title="Dermechinus horridus, an abyssal species, at thousands of meters deep"><img alt="Dermechinus horridus, an abyssal species, at thousands of meters deep" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/71/Expl1825_-_Flickr_-_NOAA_Photo_Library.jpg/250px-Expl1825_-_Flickr_-_NOAA_Photo_Library.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/71/Expl1825_-_Flickr_-_NOAA_Photo_Library.jpg/500px-Expl1825_-_Flickr_-_NOAA_Photo_Library.jpg 1.5x" data-file-width="1600" data-file-height="1200" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Dermechinus_horridus" class="mw-redirect" title="Dermechinus horridus">Dermechinus horridus</a></i>, an abyssal species, at thousands of meters deep</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Underwater_mcmurdo_sound.jpg" class="mw-file-description" title="Antarctic sea urchin (Sterechinus neumayeri) inhabits frozen seas."><img alt="Antarctic sea urchin (Sterechinus neumayeri) inhabits frozen seas." src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Underwater_mcmurdo_sound.jpg/250px-Underwater_mcmurdo_sound.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Underwater_mcmurdo_sound.jpg/500px-Underwater_mcmurdo_sound.jpg 1.5x" data-file-width="1867" data-file-height="1400" /></a></span></div> <div class="gallerytext">Antarctic sea urchin (<i><a href="/wiki/Sterechinus_neumayeri" title="Sterechinus neumayeri">Sterechinus neumayeri</a></i>) inhabits frozen seas.</div> </li> <li class="gallerybox" style="width: 180px"> <div class="thumb" style="width: 178px;"><span typeof="mw:File"><a href="/wiki/File:Colobocentrotus_atratus_Shingle_urchin.jpg" class="mw-file-description" title="The shape of the shingle urchin allows it to stay on wave-beaten cliffs."><img alt="The shape of the shingle urchin allows it to stay on wave-beaten cliffs." src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Colobocentrotus_atratus_Shingle_urchin.jpg/330px-Colobocentrotus_atratus_Shingle_urchin.jpg" decoding="async" width="178" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/a/a6/Colobocentrotus_atratus_Shingle_urchin.jpg 1.5x" data-file-width="400" data-file-height="270" /></a></span></div> <div class="gallerytext">The shape of the <a href="/wiki/Shingle_urchin" class="mw-redirect" title="Shingle urchin">shingle urchin</a> allows it to stay on wave-beaten cliffs.</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="Evolution">Evolution</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=18" title="Edit section: Evolution"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Fossil_history">Fossil history</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=19" title="Edit section: Fossil history"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Cidaridae_-_radiola_(cropped).JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/44/Cidaridae_-_radiola_%28cropped%29.JPG/500px-Cidaridae_-_radiola_%28cropped%29.JPG" decoding="async" width="370" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/44/Cidaridae_-_radiola_%28cropped%29.JPG/960px-Cidaridae_-_radiola_%28cropped%29.JPG 1.5x" data-file-width="2697" data-file-height="1274" /></a><figcaption>The thick spines (radiola) of <a href="/wiki/Cidaridae" title="Cidaridae">Cidaridae</a> were used for walking on the soft seabed.</figcaption></figure> <p>The earliest echinoid <a href="/wiki/Fossil" title="Fossil">fossils</a> date to the <a href="/wiki/Middle_Ordovician" class="mw-redirect" title="Middle Ordovician">Middle Ordovician</a> period (<i>circa</i> 465 <a href="/wiki/Million_years_ago" title="Million years ago">Mya</a>).<sup id="cite_ref-BottingAndMuir2012_48-0" class="reference"><a href="#cite_note-BottingAndMuir2012-48"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ThompsonEtAl2022_49-0" class="reference"><a href="#cite_note-ThompsonEtAl2022-49"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-BGS_50-0" class="reference"><a href="#cite_note-BGS-50"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> There is a rich fossil record, their hard tests made of <a href="/wiki/Calcite" title="Calcite">calcite</a> plates surviving in rocks from every period since then.<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> Spines are present in some well-preserved specimens, but usually only the test remains. Isolated spines are common as fossils. Some <a href="/wiki/Jurassic" title="Jurassic">Jurassic</a> and <a href="/wiki/Cretaceous" title="Cretaceous">Cretaceous</a> <a href="/wiki/Cidaroida" title="Cidaroida">Cidaroida</a> had very heavy, club-shaped spines.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p><p>Most fossil echinoids from the <a href="/wiki/Paleozoic" title="Paleozoic">Paleozoic</a> era are incomplete, consisting of isolated spines and small clusters of scattered plates from crushed individuals, mostly in <a href="/wiki/Devonian" title="Devonian">Devonian</a> and <a href="/wiki/Carboniferous" title="Carboniferous">Carboniferous</a> rocks. The shallow-water <a href="/wiki/Limestone" title="Limestone">limestones</a> from the Ordovician and <a href="/wiki/Silurian" title="Silurian">Silurian</a> periods of <a href="/wiki/Estonia" title="Estonia">Estonia</a> are famous for echinoids.<sup id="cite_ref-Kirkaldy_1967_53-0" class="reference"><a href="#cite_note-Kirkaldy_1967-53"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> Paleozoic echinoids probably inhabited relatively quiet waters. Because of their thin tests, they would certainly not have survived in the wave-battered coastal waters inhabited by many modern echinoids.<sup id="cite_ref-Kirkaldy_1967_53-1" class="reference"><a href="#cite_note-Kirkaldy_1967-53"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> Echinoids declined to near extinction at the end of the Paleozoic era, with just six species known from the <a href="/wiki/Permian" title="Permian">Permian</a> period. Only two lineages survived this period's massive extinction and into the <a href="/wiki/Triassic" title="Triassic">Triassic</a>: the genus <a href="/w/index.php?title=Miocidaris&action=edit&redlink=1" class="new" title="Miocidaris (page does not exist)">Miocidaris</a>, which gave rise to modern <a href="/wiki/Cidaroida" title="Cidaroida">cidaroida</a> (pencil urchins), and the ancestor that gave rise to the <a href="/wiki/Euechinoidea" title="Euechinoidea">euechinoids</a>. By the upper Triassic, their numbers increased again. Cidaroids have changed very little since the Late <a href="/wiki/Triassic" title="Triassic">Triassic</a>, and are the only Paleozoic echinoid group to have survived.<sup id="cite_ref-Kirkaldy_1967_53-2" class="reference"><a href="#cite_note-Kirkaldy_1967-53"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> </p><p>The euechinoids diversified into new lineages in the <a href="/wiki/Jurassic" title="Jurassic">Jurassic</a> and <a href="/wiki/Cretaceous" title="Cretaceous">Cretaceous</a> periods, and from them emerged the first irregular echinoids (the <a href="/wiki/Atelostomata" title="Atelostomata">Atelostomata</a>) during the early Jurassic.<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> </p><p>Some echinoids, such as <i><a href="/wiki/Micraster" title="Micraster">Micraster</a></i> in the chalk of the Cretaceous period, serve as zone or <a href="/wiki/Index_fossil" class="mw-redirect" title="Index fossil">index</a> fossils. Because they are abundant and evolved rapidly, they enable geologists to date the surrounding rocks.<sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> </p><p>In the <a href="/wiki/Paleogene" title="Paleogene">Paleogene</a> and <a href="/wiki/Neogene" title="Neogene">Neogene</a> periods (<i>circa</i> 66 to 2.6 Mya), <a href="/wiki/Sand_dollar" title="Sand dollar">sand dollars</a> (Clypeasteroida) arose. Their distinctive, flattened tests and tiny spines were adapted to life on or under loose sand in shallow water, and they are abundant as fossils in southern European limestones and sandstones.<sup id="cite_ref-Kirkaldy_1967_53-3" class="reference"><a href="#cite_note-Kirkaldy_1967-53"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-packed"> <li class="gallerybox" style="width: 148px"> <div class="thumb" style="width: 146px;"><span typeof="mw:File"><a href="/wiki/File:Archaeocidaris_brownwoodensis_MHNT.jpg" class="mw-file-description" title="Archaeocidaris brownwoodensis, Cidaroida, Carboniferous, c. 300 mya"><img alt="Archaeocidaris brownwoodensis, Cidaroida, Carboniferous, c. 300 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/62/Archaeocidaris_brownwoodensis_MHNT.jpg/219px-Archaeocidaris_brownwoodensis_MHNT.jpg" decoding="async" width="146" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/62/Archaeocidaris_brownwoodensis_MHNT.jpg/328px-Archaeocidaris_brownwoodensis_MHNT.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/62/Archaeocidaris_brownwoodensis_MHNT.jpg/437px-Archaeocidaris_brownwoodensis_MHNT.jpg 2x" data-file-width="5493" data-file-height="4522" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Archaeocidaris" title="Archaeocidaris">Archaeocidaris</a> brownwoodensis</i>, <a href="/wiki/Cidaroida" title="Cidaroida">Cidaroida</a>, <a href="/wiki/Carboniferous" title="Carboniferous">Carboniferous</a>, c. 300 mya</div> </li> <li class="gallerybox" style="width: 178.66666666667px"> <div class="thumb" style="width: 176.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Miocidaris_coaeva_MHNT.PAL.2006.94.jpg" class="mw-file-description" title="Miocidaris coaeva, Cidaroida, Middle Triassic, c. 240 mya"><img alt="Miocidaris coaeva, Cidaroida, Middle Triassic, c. 240 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Miocidaris_coaeva_MHNT.PAL.2006.94.jpg/330px-Miocidaris_coaeva_MHNT.PAL.2006.94.jpg" decoding="async" width="177" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Miocidaris_coaeva_MHNT.PAL.2006.94.jpg/500px-Miocidaris_coaeva_MHNT.PAL.2006.94.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Miocidaris_coaeva_MHNT.PAL.2006.94.jpg/960px-Miocidaris_coaeva_MHNT.PAL.2006.94.jpg 2x" data-file-width="4478" data-file-height="3044" /></a></span></div> <div class="gallerytext"><i><a href="/w/index.php?title=Miocidaris&action=edit&redlink=1" class="new" title="Miocidaris (page does not exist)">Miocidaris</a> coaeva</i>, <a href="/wiki/Cidaroida" title="Cidaroida">Cidaroida</a>, Middle <a href="/wiki/Triassic" title="Triassic">Triassic</a>, c. 240 mya</div> </li> <li class="gallerybox" style="width: 158px"> <div class="thumb" style="width: 156px;"><span typeof="mw:File"><a href="/wiki/File:Clypeus_plotti,_echinoid,_Middle_Jurassic,_Gloucester,_Gloucestershire,_England_-_Houston_Museum_of_Natural_Science_-_DSC01800.JPG" class="mw-file-description" title="Clypeus plotti, Irregularia, Middle Jurassic, c. 162 mya"><img alt="Clypeus plotti, Irregularia, Middle Jurassic, c. 162 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/76/Clypeus_plotti%2C_echinoid%2C_Middle_Jurassic%2C_Gloucester%2C_Gloucestershire%2C_England_-_Houston_Museum_of_Natural_Science_-_DSC01800.JPG/250px-Clypeus_plotti%2C_echinoid%2C_Middle_Jurassic%2C_Gloucester%2C_Gloucestershire%2C_England_-_Houston_Museum_of_Natural_Science_-_DSC01800.JPG" decoding="async" width="156" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/76/Clypeus_plotti%2C_echinoid%2C_Middle_Jurassic%2C_Gloucester%2C_Gloucestershire%2C_England_-_Houston_Museum_of_Natural_Science_-_DSC01800.JPG/500px-Clypeus_plotti%2C_echinoid%2C_Middle_Jurassic%2C_Gloucester%2C_Gloucestershire%2C_England_-_Houston_Museum_of_Natural_Science_-_DSC01800.JPG 1.5x" data-file-width="4060" data-file-height="3126" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Clypeus_(echinoderm)" class="mw-redirect" title="Clypeus (echinoderm)">Clypeus</a> plotti</i>, <a href="/wiki/Irregularia" title="Irregularia">Irregularia</a>, Middle <a href="/wiki/Jurassic" title="Jurassic">Jurassic</a>, c. 162 mya</div> </li> <li class="gallerybox" style="width: 162px"> <div class="thumb" style="width: 160px;"><span typeof="mw:File"><a href="/wiki/File:Fossil_Echinoid_Echinocorys.jpg" class="mw-file-description" title="Echinocorys, Holasteroida, Upper Cretaceous, c. 80 mya"><img alt="Echinocorys, Holasteroida, Upper Cretaceous, c. 80 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/40/Fossil_Echinoid_Echinocorys.jpg/240px-Fossil_Echinoid_Echinocorys.jpg" decoding="async" width="160" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/4/40/Fossil_Echinoid_Echinocorys.jpg 1.5x" data-file-width="300" data-file-height="225" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Echinocorys" title="Echinocorys">Echinocorys</a></i>, <a href="/wiki/Holasteroida" title="Holasteroida">Holasteroida</a>, Upper <a href="/wiki/Cretaceous" title="Cretaceous">Cretaceous</a>, c. 80 mya</div> </li> <li class="gallerybox" style="width: 124.66666666667px"> <div class="thumb" style="width: 122.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG" class="mw-file-description" title="Echinolampas ovalis, Cassiduloida, Middle Eocene, c. 40 mya"><img alt="Echinolampas ovalis, Cassiduloida, Middle Eocene, c. 40 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/45/Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG/250px-Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG" decoding="async" width="123" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/45/Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG/330px-Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/45/Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG/500px-Echinolampas_ovalis_M_Eocene_Civrac-en-M%C3%A9doc_France.JPG 2x" data-file-width="2408" data-file-height="2356" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Echinolampas" title="Echinolampas">Echinolampas</a> ovalis</i>, <a href="/wiki/Cassiduloida" title="Cassiduloida">Cassiduloida</a>, Middle <a href="/wiki/Eocene" title="Eocene">Eocene</a>, c. 40 mya</div> </li> <li class="gallerybox" style="width: 128.66666666667px"> <div class="thumb" style="width: 126.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Clypeaster_portentosus.jpg" class="mw-file-description" title="Clypeaster portentosus, Clypeasteroida, Miocene, c. 10 mya"><img alt="Clypeaster portentosus, Clypeasteroida, Miocene, c. 10 mya" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Clypeaster_portentosus.jpg/250px-Clypeaster_portentosus.jpg" decoding="async" width="127" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Clypeaster_portentosus.jpg/330px-Clypeaster_portentosus.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Clypeaster_portentosus.jpg/500px-Clypeaster_portentosus.jpg 2x" data-file-width="758" data-file-height="720" /></a></span></div> <div class="gallerytext"><i><a href="/wiki/Clypeaster" title="Clypeaster">Clypeaster</a> portentosus</i>, <a href="/wiki/Clypeasteroida" class="mw-redirect" title="Clypeasteroida">Clypeasteroida</a>, <a href="/wiki/Miocene" title="Miocene">Miocene</a>, c. 10 mya</div> </li> <li class="gallerybox" style="width: 124.66666666667px"> <div class="thumb" style="width: 122.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Clypeus_plotii.JPG" class="mw-file-description" title="Clypeus ploti gives its name to the Clypeus Grit of Western England, part of the Oolite.[55]"><img alt="Clypeus ploti gives its name to the Clypeus Grit of Western England, part of the Oolite.[55]" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Clypeus_plotii.JPG/250px-Clypeus_plotii.JPG" decoding="async" width="123" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Clypeus_plotii.JPG/330px-Clypeus_plotii.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Clypeus_plotii.JPG/500px-Clypeus_plotii.JPG 2x" data-file-width="1778" data-file-height="1738" /></a></span></div> <div class="gallerytext"><i>Clypeus ploti</i> gives its name to the <a href="/wiki/Clypeus_Grit" class="mw-redirect" title="Clypeus Grit">Clypeus Grit</a> of Western England, part of the Oolite.<sup id="cite_ref-BGS_-_CG_56-0" class="reference"><a href="#cite_note-BGS_-_CG-56"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup></div> </li> </ul> <div class="mw-heading mw-heading3"><h3 id="Phylogeny">Phylogeny</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=20" title="Edit section: Phylogeny"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="External">External</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=21" title="Edit section: External"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Echinoids are <a href="/wiki/Deuterostome" title="Deuterostome">deuterostome</a> animals, like the <a href="/wiki/Chordate" title="Chordate">chordates</a>. A 2014 analysis of 219 genes from all classes of echinoderms gives the following <a href="/wiki/Phylogenetic_tree" title="Phylogenetic tree">phylogenetic tree</a>.<sup id="cite_ref-TelfordLowe2014_57-0" class="reference"><a href="#cite_note-TelfordLowe2014-57"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> Approximate dates of branching of major clades are shown in millions of years ago (mya). </p> <div class="clade"><style data-mw-deduplicate="TemplateStyles:r1261294616">body.skin-vector-2022 .mw-parser-output div.clade,body.skin-minerva .mw-parser-output div.clade{overflow-x:auto;overflow-y:hidden}body.skin-minerva .mw-parser-output div.clade p{font-size:inherit}.mw-parser-output table.clade{border-spacing:0;margin:0;font-size:100%;line-height:100%;border-collapse:separate;width:auto;display:table}.mw-parser-output table.clade table.clade{width:100%;line-height:inherit}.mw-parser-output table.clade td.clade-label{min-width:0.2em;width:0.2em;padding:0.1em 0.25em;vertical-align:bottom;text-align:center;border-left:1px solid;border-bottom:1px solid;white-space:nowrap}.mw-parser-output table.clade td.clade-label::before,.mw-parser-output table.clade td.clade-slabel::before{content:"\2060 "}.mw-parser-output table.clade td.clade-fixed-width{overflow:hidden;text-overflow:ellipsis}.mw-parser-output table.clade td.clade-fixed-width:hover{overflow:visible}.mw-parser-output table.clade td.clade-label.first{border-left:none;border-right:none}.mw-parser-output table.clade td.clade-label.reverse{border-left:none;border-right:1px solid}.mw-parser-output table.clade td.clade-slabel{padding:0.1em 0.25em;vertical-align:top;text-align:center;border-left:1px solid;white-space:nowrap}.mw-parser-output table.clade td.clade-slabel:hover{overflow:visible}.mw-parser-output table.clade td.clade-slabel.last{border-left:none;border-right:none}.mw-parser-output table.clade td.clade-slabel.reverse{border-left:none;border-right:1px solid}.mw-parser-output table.clade td.clade-bar{vertical-align:middle;text-align:left;padding:0 0.5em;position:relative}.mw-parser-output table.clade td.clade-bar.reverse{text-align:right;position:relative}.mw-parser-output table.clade td.clade-leaf{border:0;padding:0;text-align:left}.mw-parser-output table.clade td.clade-leaf p{padding-right:5px;padding-left:2px}.mw-parser-output table.clade td.clade-leafR{border:0;padding:0;text-align:right}.mw-parser-output table.clade td.clade-leafR p{padding-left:5px;padding-right:2px}.mw-parser-output table.clade td.clade-leaf.reverse{text-align:right}.mw-parser-output table.clade td.clade-leaf.reverse p{padding-left:5px;padding-right:2px}.mw-parser-output table.clade:hover span.linkA{background-color:yellow}.mw-parser-output table.clade:hover span.linkB{background-color:green}</style> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Bilateria" title="Bilateria">Bilateria</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Xenacoelomorpha" title="Xenacoelomorpha">Xenacoelomorpha</a> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Proporus_sp.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Proporus_sp.png/120px-Proporus_sp.png" decoding="async" width="80" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Proporus_sp.png/250px-Proporus_sp.png 2x" data-file-width="1428" data-file-height="812" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Nephrozoa" title="Nephrozoa">Nephrozoa</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Deuterostomia" class="mw-redirect" title="Deuterostomia">Deuterostomia</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Chordata" class="mw-redirect" title="Chordata">Chordata</a> and allies </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Common_carp_(white_background).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Common_carp_%28white_background%29.jpg/80px-Common_carp_%28white_background%29.jpg" decoding="async" width="80" height="34" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Common_carp_%28white_background%29.jpg/120px-Common_carp_%28white_background%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Common_carp_%28white_background%29.jpg/160px-Common_carp_%28white_background%29.jpg 2x" data-file-width="879" data-file-height="379" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Echinodermata" class="mw-redirect" title="Echinodermata">Echinodermata</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Echinozoa" title="Echinozoa">Echinozoa</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Holothuroidea" class="mw-redirect" title="Holothuroidea">Holothuroidea</a> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Holothuroidea.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Holothuroidea.JPG/120px-Holothuroidea.JPG" decoding="async" width="80" height="42" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Holothuroidea.JPG/250px-Holothuroidea.JPG 2x" data-file-width="3469" data-file-height="1805" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"><i> Sea cucumbers </i> </td></tr> <tr> <td class="clade-label"><b>Echinoidea</b> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Red_sea_urchin_2.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Red_sea_urchin_2.jpg/70px-Red_sea_urchin_2.jpg" decoding="async" width="70" height="65" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Red_sea_urchin_2.jpg/105px-Red_sea_urchin_2.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Red_sea_urchin_2.jpg/140px-Red_sea_urchin_2.jpg 2x" data-file-width="1300" data-file-height="1200" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel last">c. 450 mya </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Asterozoa" title="Asterozoa">Asterozoa</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><a href="/wiki/Ophiuroidea" class="mw-redirect" title="Ophiuroidea">Ophiuroidea</a> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Ophiura_ophiura.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Ophiura_ophiura.jpg/80px-Ophiura_ophiura.jpg" decoding="async" width="80" height="60" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Ophiura_ophiura.jpg/120px-Ophiura_ophiura.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Ophiura_ophiura.jpg/160px-Ophiura_ophiura.jpg 2x" data-file-width="1200" data-file-height="900" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"><i>Brittle stars</i> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Asteroidea" class="mw-redirect" title="Asteroidea">Asteroidea</a> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Portugal_20140812-DSC01434_(21371237591).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/Portugal_20140812-DSC01434_%2821371237591%29.jpg/120px-Portugal_20140812-DSC01434_%2821371237591%29.jpg" decoding="async" width="80" height="53" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/Portugal_20140812-DSC01434_%2821371237591%29.jpg/250px-Portugal_20140812-DSC01434_%2821371237591%29.jpg 2x" data-file-width="5472" data-file-height="3648" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel last"><i>Starfish</i> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Crinoidea" class="mw-redirect" title="Crinoidea">Crinoidea</a> </td> <td rowspan="2" class="clade-leaf"> <p><span typeof="mw:File"><a href="/wiki/File:Crinoid_on_the_reef_of_Batu_Moncho_Island_(cropped).JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/10/Crinoid_on_the_reef_of_Batu_Moncho_Island_%28cropped%29.JPG/60px-Crinoid_on_the_reef_of_Batu_Moncho_Island_%28cropped%29.JPG" decoding="async" width="50" height="76" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/10/Crinoid_on_the_reef_of_Batu_Moncho_Island_%28cropped%29.JPG/120px-Crinoid_on_the_reef_of_Batu_Moncho_Island_%28cropped%29.JPG 1.5x" data-file-width="2153" data-file-height="3257" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel last"><i>Crinoids</i> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last">c. 500 mya </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel">>540 mya </td></tr> <tr> <td class="clade-label"><a href="/wiki/Protostomia" class="mw-redirect" title="Protostomia">Protostomia</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Ecdysozoa" title="Ecdysozoa">Ecdysozoa</a> <span typeof="mw:File"><a href="/wiki/File:Long_nosed_weevil_edit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Long_nosed_weevil_edit.jpg/80px-Long_nosed_weevil_edit.jpg" decoding="async" width="80" height="53" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Long_nosed_weevil_edit.jpg/120px-Long_nosed_weevil_edit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Long_nosed_weevil_edit.jpg/160px-Long_nosed_weevil_edit.jpg 2x" data-file-width="1600" data-file-height="1067" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Spiralia" title="Spiralia">Spiralia</a> <span typeof="mw:File"><a href="/wiki/File:Grapevinesnail_01.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/69/Grapevinesnail_01.jpg/120px-Grapevinesnail_01.jpg" decoding="async" width="80" height="47" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/69/Grapevinesnail_01.jpg/250px-Grapevinesnail_01.jpg 2x" data-file-width="1024" data-file-height="604" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last">610 mya </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last">650 mya </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> <div class="mw-heading mw-heading4"><h4 id="Internal">Internal</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=22" title="Edit section: Internal"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The phylogeny of the sea urchins is as follows:<sup id="cite_ref-PlanetZiegler2012_58-0" class="reference"><a href="#cite_note-PlanetZiegler2012-58"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KrohSmith2010_59-0" class="reference"><a href="#cite_note-KrohSmith2010-59"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p> <div class="clade"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"><b>Echinoidea</b> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Cidaroida" title="Cidaroida">Cidaroida</a> <span typeof="mw:File"><a href="/wiki/File:Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg/50px-Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg" decoding="async" width="50" height="43" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg/75px-Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg/100px-Fish4570_-_Flickr_-_NOAA_Photo_Library.jpg 2x" data-file-width="1671" data-file-height="1425" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Euechinoidea" title="Euechinoidea">Euechinoidea</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Echinothurioida" title="Echinothurioida">Echinothurioida</a> <span typeof="mw:File"><a href="/wiki/File:Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/54/Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg/60px-Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg" decoding="async" width="60" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/54/Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg/90px-Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/54/Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg/120px-Toxic_Leather_Sea_Urchin_-_Asthenosoma_marisrubri.jpg 2x" data-file-width="4000" data-file-height="3000" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/w/index.php?title=Acroechinoidea&action=edit&redlink=1" class="new" title="Acroechinoidea (page does not exist)">Acroechinoidea</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Diadematoida" title="Diadematoida">Diadematoida</a> <span typeof="mw:File"><a href="/wiki/File:Diadema_antillarum_Flower_Garden_Banks.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Diadema_antillarum_Flower_Garden_Banks.jpg/60px-Diadema_antillarum_Flower_Garden_Banks.jpg" decoding="async" width="60" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Diadema_antillarum_Flower_Garden_Banks.jpg/120px-Diadema_antillarum_Flower_Garden_Banks.jpg 1.5x" data-file-width="2033" data-file-height="1350" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Irregularia" title="Irregularia">Irregularia</a> <span typeof="mw:File"><a href="/wiki/File:Clypeaster_rosaceus_(San_Salvador_Island,_Bahamas)_3.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Clypeaster_rosaceus_%28San_Salvador_Island%2C_Bahamas%29_3.jpg/60px-Clypeaster_rosaceus_%28San_Salvador_Island%2C_Bahamas%29_3.jpg" decoding="async" width="45" height="54" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Clypeaster_rosaceus_%28San_Salvador_Island%2C_Bahamas%29_3.jpg/120px-Clypeaster_rosaceus_%28San_Salvador_Island%2C_Bahamas%29_3.jpg 1.5x" data-file-width="1438" data-file-height="1713" /></a></span> <span typeof="mw:File"><a href="/wiki/File:Pourtalesia_wandeli.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Pourtalesia_wandeli.png/60px-Pourtalesia_wandeli.png" decoding="async" width="60" height="37" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Pourtalesia_wandeli.png/120px-Pourtalesia_wandeli.png 1.5x" data-file-width="361" data-file-height="220" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Pedinoida" title="Pedinoida">Pedinoida</a> <span typeof="mw:File"><a href="/wiki/File:Caenopedina_hawaiiensis.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Caenopedina_hawaiiensis.jpg/60px-Caenopedina_hawaiiensis.jpg" decoding="async" width="60" height="34" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Caenopedina_hawaiiensis.jpg/90px-Caenopedina_hawaiiensis.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Caenopedina_hawaiiensis.jpg/120px-Caenopedina_hawaiiensis.jpg 2x" data-file-width="1920" data-file-height="1080" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Salenioida" title="Salenioida">Salenioida</a> <span typeof="mw:File"><a href="/wiki/File:Salenocidaris_hastigera.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Salenocidaris_hastigera.png/60px-Salenocidaris_hastigera.png" decoding="async" width="60" height="32" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Salenocidaris_hastigera.png/120px-Salenocidaris_hastigera.png 1.5x" data-file-width="518" data-file-height="276" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Echinacea_(animal)" title="Echinacea (animal)">Echinacea</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Stomopneustidae" title="Stomopneustidae">Stomopneustidae</a> <span typeof="mw:File"><a href="/wiki/File:S._variolaris.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/56/S._variolaris.jpg/60px-S._variolaris.jpg" decoding="async" width="60" height="47" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/56/S._variolaris.jpg/90px-S._variolaris.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/56/S._variolaris.jpg/120px-S._variolaris.jpg 2x" data-file-width="1200" data-file-height="948" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Arbaciidae" class="mw-redirect" title="Arbaciidae">Arbaciidae</a> <span typeof="mw:File"><a href="/wiki/File:Arbacia_lixula_03.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Arbacia_lixula_03.JPG/60px-Arbacia_lixula_03.JPG" decoding="async" width="60" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Arbacia_lixula_03.JPG/90px-Arbacia_lixula_03.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/Arbacia_lixula_03.JPG/120px-Arbacia_lixula_03.JPG 2x" data-file-width="4000" data-file-height="3000" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Camarodonta" title="Camarodonta">Camarodonta</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Parasaleniidae" title="Parasaleniidae">Parasaleniidae</a> <span typeof="mw:File"><a href="/wiki/File:Parasalenia_poehlii.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Parasalenia_poehlii.JPG/60px-Parasalenia_poehlii.JPG" decoding="async" width="60" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Parasalenia_poehlii.JPG/120px-Parasalenia_poehlii.JPG 1.5x" data-file-width="1505" data-file-height="1136" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Temnopleuridae" title="Temnopleuridae">Temnopleuridae</a> <span typeof="mw:File"><a href="/wiki/File:Salmacis_sphaeroides.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Salmacis_sphaeroides.jpg/60px-Salmacis_sphaeroides.jpg" decoding="async" width="60" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Salmacis_sphaeroides.jpg/90px-Salmacis_sphaeroides.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Salmacis_sphaeroides.jpg/120px-Salmacis_sphaeroides.jpg 2x" data-file-width="6000" data-file-height="4000" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Trigonocidaridae" title="Trigonocidaridae">Trigonocidaridae</a> </p> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"><a href="/wiki/Echinoida" title="Echinoida">Echinoida</a> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Echinidae" title="Echinidae">Echinidae</a> <span typeof="mw:File"><a href="/wiki/File:Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg/60px-Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg" decoding="async" width="60" height="54" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg/90px-Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg/120px-Riccio_Melone_a_Capo_Caccia_adventurediving.it.jpg 2x" data-file-width="1659" data-file-height="1500" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Parechinidae" title="Parechinidae">Parechinidae</a> <span typeof="mw:File"><a href="/wiki/File:Psammechinus_microtuberculatus.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Psammechinus_microtuberculatus.jpg/60px-Psammechinus_microtuberculatus.jpg" decoding="async" width="60" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Psammechinus_microtuberculatus.jpg/120px-Psammechinus_microtuberculatus.jpg 1.5x" data-file-width="300" data-file-height="200" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Toxopneustidae" title="Toxopneustidae">Toxopneustidae</a> <span typeof="mw:File"><a href="/wiki/File:Toxopneustes_pileolus_(Sea_urchin).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Toxopneustes_pileolus_%28Sea_urchin%29.jpg/60px-Toxopneustes_pileolus_%28Sea_urchin%29.jpg" decoding="async" width="60" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Toxopneustes_pileolus_%28Sea_urchin%29.jpg/120px-Toxopneustes_pileolus_%28Sea_urchin%29.jpg 1.5x" data-file-width="2118" data-file-height="1589" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1261294616" /> <table class="clade"> <tbody><tr> <td class="clade-label first"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Echinometridae" title="Echinometridae">Echinometridae</a> <span typeof="mw:File"><a href="/wiki/File:Heterocentrotus_mammillatus_in_situ_from_Hawaii.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Heterocentrotus_mammillatus_in_situ_from_Hawaii.JPG/60px-Heterocentrotus_mammillatus_in_situ_from_Hawaii.JPG" decoding="async" width="60" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Heterocentrotus_mammillatus_in_situ_from_Hawaii.JPG/120px-Heterocentrotus_mammillatus_in_situ_from_Hawaii.JPG 1.5x" data-file-width="3264" data-file-height="2448" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel"> </td></tr> <tr> <td class="clade-label"> </td> <td rowspan="2" class="clade-leaf"> <p><a href="/wiki/Strongylocentrotidae" title="Strongylocentrotidae">Strongylocentrotidae</a> <span typeof="mw:File"><a href="/wiki/File:Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg/60px-Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg" decoding="async" width="60" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg/90px-Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/74/Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg/120px-Strongylocentrotus_franciscanus_at_Telegraph_Cove.jpg 2x" data-file-width="1600" data-file-height="1072" /></a></span> </p> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last"> </td></tr></tbody></table></div> </td></tr> <tr> <td class="clade-slabel last">450 mya </td></tr></tbody></table></div> <p>The phylogenetic study from 2022 presents a different topology of the <a href="/wiki/Euechinoidea" title="Euechinoidea">Euechinoidea</a> phylogenetic tree. <a href="/wiki/Irregularia" title="Irregularia">Irregularia</a> are sister group of <a href="/wiki/Echinacea_(animal)" title="Echinacea (animal)">Echinacea</a> (including <a href="/wiki/Salenioida" title="Salenioida">Salenioida</a>) forming a common clade <a href="/wiki/Carinacea" title="Carinacea">Carinacea</a>, basal groups <a href="/wiki/Aspidodiadematoida" class="mw-redirect" title="Aspidodiadematoida">Aspidodiadematoida</a>, <a href="/wiki/Diadematoida" title="Diadematoida">Diadematoida</a>, <a href="/wiki/Echinothurioida" title="Echinothurioida">Echinothurioida</a>, <a href="/w/index.php?title=Micropygoida&action=edit&redlink=1" class="new" title="Micropygoida (page does not exist)">Micropygoida</a>, and <a href="/wiki/Pedinoida" title="Pedinoida">Pedinoida</a> are comprised in a common basal clade <a href="/w/index.php?title=Aulodonta&action=edit&redlink=1" class="new" title="Aulodonta (page does not exist)">Aulodonta</a>.<sup id="cite_ref-Koch_2022_60-0" class="reference"><a href="#cite_note-Koch_2022-60"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Relation_to_humans">Relation to humans</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=23" title="Edit section: Relation to humans"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Injuries">Injuries</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=24" title="Edit section: Injuries"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Sea_urchin_injury" title="Sea urchin injury">Sea urchin injury</a></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Sea-urchin-injury.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/0/01/Sea-urchin-injury.jpg/220px-Sea-urchin-injury.jpg" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/0/01/Sea-urchin-injury.jpg/330px-Sea-urchin-injury.jpg 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/0/01/Sea-urchin-injury.jpg/440px-Sea-urchin-injury.jpg 2x" data-file-width="1280" data-file-height="848" /></a><figcaption>Sea urchin injury on the top side of the foot. This injury resulted in some skin staining from the natural purple-black dye of the urchin.</figcaption></figure> <p>Sea urchin injuries are puncture wounds inflicted by the animal's brittle, fragile spines.<sup id="cite_ref-Andrews_61-0" class="reference"><a href="#cite_note-Andrews-61"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> These are a common source of injury to ocean swimmers, especially along coastal surfaces where coral with stationary sea urchins are present. Their stings vary in severity depending on the species. Their spines can be venomous or cause infection. <a href="/wiki/Granuloma" title="Granuloma">Granuloma</a> and staining of the skin from the natural dye inside the sea urchin can also occur. Breathing problems may indicate a serious reaction to toxins in the sea urchin.<sup id="cite_ref-62" class="reference"><a href="#cite_note-62"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> They inflict a painful wound when they penetrate human skin, but are not themselves dangerous if fully removed promptly; if left in the skin, further problems may occur.<sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Science">Science</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=25" title="Edit section: Science"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sea urchins are traditional <a href="/wiki/Model_organisms" class="mw-redirect" title="Model organisms">model organisms</a> in <a href="/wiki/Developmental_biology" title="Developmental biology">developmental biology</a>. This use originated in the 1800s, when their embryonic development became easily viewed by microscopy. The transparency of the urchin's eggs enabled them to be used to observe that <a href="/wiki/Sperm" title="Sperm">sperm</a> cells actually fertilize <a href="/wiki/Ova" class="mw-redirect" title="Ova">ova</a>.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> They continue to be used for embryonic studies, as <a href="/wiki/Prenatal_development" title="Prenatal development">prenatal development</a> continues to seek testing for fatal diseases. Sea urchins are being used in longevity studies for comparison between the young and old of the species, particularly for their ability to regenerate tissue as needed.<sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> Scientists at the <a href="/wiki/University_of_St_Andrews" title="University of St Andrews">University of St Andrews</a> have discovered a genetic sequence, the '2A' region, in sea urchins previously thought to have belonged only to viruses like <a href="/wiki/Foot-and-mouth_disease_virus" title="Foot-and-mouth disease virus">foot-and-mouth disease virus</a>.<sup id="cite_ref-66" class="reference"><a href="#cite_note-66"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup> More recently, <a href="/wiki/Eric_H._Davidson" title="Eric H. Davidson">Eric H. Davidson</a> and <a href="/wiki/Roy_John_Britten" title="Roy John Britten">Roy John Britten</a> argued for the use of urchins as a model organism due to their easy availability, high fecundity, and long lifespan. Beyond <a href="/wiki/Embryology" title="Embryology">embryology</a>, urchins provide an opportunity to research <a href="/wiki/Cis-regulatory_element" title="Cis-regulatory element">cis-regulatory elements</a>.<sup id="cite_ref-67" class="reference"><a href="#cite_note-67"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> Oceanography has taken an interest in monitoring the health of urchins and their populations as a way to assess overall <a href="/wiki/Ocean_acidification" title="Ocean acidification">ocean acidification</a>,<sup id="cite_ref-68" class="reference"><a href="#cite_note-68"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup> temperatures, and ecological impacts. </p><p>The organism's evolutionary placement and unique embryology with five-fold symmetry were the major arguments in the proposal to seek the sequencing of its <a href="/wiki/Genome" title="Genome">genome</a>. Importantly, urchins act as the closest living relative to chordates and thus are of interest for the light they can shed on the evolution of <a href="/wiki/Vertebrate" title="Vertebrate">vertebrates</a>.<sup id="cite_ref-ncbi.nlm.nih.gov_69-0" class="reference"><a href="#cite_note-ncbi.nlm.nih.gov-69"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> The genome of <i><a href="/wiki/Strongylocentrotus_purpuratus" title="Strongylocentrotus purpuratus">Strongylocentrotus purpuratus</a></i> was completed in 2006 and established homology between sea urchin and vertebrate <a href="/wiki/Immune_system" title="Immune system">immune system</a>-related genes. Sea urchins code for at least 222 <a href="/wiki/Toll-like_receptor" title="Toll-like receptor">Toll-like receptor</a> genes and over 200 genes related to the <a href="/wiki/Nod-like-receptor" class="mw-redirect" title="Nod-like-receptor">Nod-like-receptor</a> family found in vertebrates.<sup id="cite_ref-70" class="reference"><a href="#cite_note-70"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> This increases its usefulness as a valuable model organism for studying the <a href="/wiki/Evolution" title="Evolution">evolution</a> of <a href="/wiki/Innate_immunity" class="mw-redirect" title="Innate immunity">innate immunity</a>. The sequencing also revealed that while some genes were thought to be limited to vertebrates, there were also innovations that have previously never been seen outside the chordate classification, such as immune transcription factors <a href="/wiki/PU.1" class="mw-redirect" title="PU.1">PU.1</a> and <a href="/wiki/SPIB" title="SPIB">SPIB</a>.<sup id="cite_ref-ncbi.nlm.nih.gov_69-1" class="reference"><a href="#cite_note-ncbi.nlm.nih.gov-69"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="As_food">As food</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=26" title="Edit section: As food"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Fresh_Sea_Urchin_(2678940158).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Fresh_Sea_Urchin_%282678940158%29.jpg/250px-Fresh_Sea_Urchin_%282678940158%29.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Fresh_Sea_Urchin_%282678940158%29.jpg/330px-Fresh_Sea_Urchin_%282678940158%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Fresh_Sea_Urchin_%282678940158%29.jpg/500px-Fresh_Sea_Urchin_%282678940158%29.jpg 2x" data-file-width="3648" data-file-height="2432" /></a><figcaption>Sea urchin cut open, revealing the roe inside</figcaption></figure> <p>The <a href="/wiki/Gonad" title="Gonad">gonads</a> of both male and female sea urchins, sometimes euphemized as sea urchin "roe" or "corals",<sup id="cite_ref-71" class="reference"><a href="#cite_note-71"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup> are culinary delicacies in many parts of the world, especially Japan.<sup id="cite_ref-Davidson,_Oxford_Companion_72-0" class="reference"><a href="#cite_note-Davidson,_Oxford_Companion-72"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-73" class="reference"><a href="#cite_note-73"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-74" class="reference"><a href="#cite_note-74"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> In Japan, sea urchin is known as <i>uni</i><span style="font-weight: normal"> (<span title="Japanese-language text"><span lang="ja">うに</span></span>)</span>, and its gonads (the only meaty, edible parts of the animal) can retail for as much as ¥40,000 ($360) per kilogram;<sup id="cite_ref-smh_75-0" class="reference"><a href="#cite_note-smh-75"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> they are served raw as <a href="/wiki/Sashimi" title="Sashimi">sashimi</a> or in <a href="/wiki/Sushi" title="Sushi">sushi</a>, with <a href="/wiki/Soy_sauce" title="Soy sauce">soy sauce</a> and <a href="/wiki/Wasabi" title="Wasabi">wasabi</a>. Japan imports large quantities from the United States, <a href="/wiki/South_Korea" title="South Korea">South Korea</a>, and other producers. Japan consumes 50,000 tons annually, amounting to over 80% of global production.<sup id="cite_ref-76" class="reference"><a href="#cite_note-76"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> Japanese demand for sea urchins has raised concerns about overfishing.<sup id="cite_ref-77" class="reference"><a href="#cite_note-77"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> </p><p>Sea urchins are commonly eaten stuffed with rice in the traditional <i><a href="/wiki/Oko-oko" title="Oko-oko">oko-oko</a></i> dish among the <a href="/wiki/Sama-Bajau_people" class="mw-redirect" title="Sama-Bajau people">Sama-Bajau people</a> of the <a href="/wiki/Philippines" title="Philippines">Philippines</a>.<sup id="cite_ref-kso_1_78-0" class="reference"><a href="#cite_note-kso_1-78"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup> They were once foraged by coastal Malay communities of <a href="/wiki/Singapore" title="Singapore">Singapore</a> who call them <span title="Standard Malay-language text"><i lang="zsm">jani</i></span>.<sup id="cite_ref-79" class="reference"><a href="#cite_note-79"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> In New Zealand, <i><a href="/wiki/Evechinus_chloroticus" class="mw-redirect" title="Evechinus chloroticus">Evechinus chloroticus</a></i>, known as <span title="Māori-language text"><i lang="mi">kina</i></span> in <a href="/wiki/M%C4%81ori_language" title="Māori language">Māori</a>, is a delicacy, traditionally eaten raw. Though New Zealand fishermen would like to export them to Japan, their quality is too variable.<sup id="cite_ref-80" class="reference"><a href="#cite_note-80"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> </p><p>In <a href="/wiki/Mediterranean_cuisine" title="Mediterranean cuisine">Mediterranean cuisines</a>, <i><a href="/wiki/Paracentrotus_lividus" title="Paracentrotus lividus">Paracentrotus lividus</a></i> is often eaten raw, or with lemon,<sup id="cite_ref-81" class="reference"><a href="#cite_note-81"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> and known as <span title="Italian-language text"><i lang="it">ricci</i></span> on Italian menus where it is sometimes used in pasta sauces. It can also flavour <a href="/wiki/Omelette" title="Omelette">omelettes</a>, <a href="/wiki/Scrambled_eggs" title="Scrambled eggs">scrambled eggs</a>, <a href="/wiki/Fish_soup" title="Fish soup">fish soup</a>,<sup id="cite_ref-82" class="reference"><a href="#cite_note-82"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Mayonnaise" title="Mayonnaise">mayonnaise</a>, <a href="/wiki/B%C3%A9chamel_sauce" title="Béchamel sauce">béchamel sauce</a> for tartlets,<sup id="cite_ref-83" class="reference"><a href="#cite_note-83"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup> the <span title="French-language text"><i lang="fr">boullie</i></span> for a <a href="/wiki/Souffl%C3%A9" title="Soufflé">soufflé</a>,<sup id="cite_ref-84" class="reference"><a href="#cite_note-84"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> or <a href="/wiki/Hollandaise_sauce" title="Hollandaise sauce">Hollandaise sauce</a> to make a fish sauce.<sup id="cite_ref-85" class="reference"><a href="#cite_note-85"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> In the region of <a href="/wiki/Marseille" title="Marseille">Marseille</a>, sea urchin are commonly eaten in dedicated food festival called <i>oursinade</i>.<sup id="cite_ref-86" class="reference"><a href="#cite_note-86"><span class="cite-bracket">[</span>85<span class="cite-bracket">]</span></a></sup> </p><p>On the Pacific Coast of North America, <i><a href="/wiki/Strongylocentrotus_franciscanus" class="mw-redirect" title="Strongylocentrotus franciscanus">Strongylocentrotus franciscanus</a></i> was praised by <a href="/wiki/Euell_Gibbons" title="Euell Gibbons">Euell Gibbons</a>; <i><a href="/wiki/Strongylocentrotus_purpuratus" title="Strongylocentrotus purpuratus">Strongylocentrotus purpuratus</a></i> is also eaten.<sup id="cite_ref-Davidson,_Oxford_Companion_72-1" class="reference"><a href="#cite_note-Davidson,_Oxford_Companion-72"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Native_Americans_in_California" class="mw-redirect" title="Native Americans in California">Native Americans in California</a> are also known to eat sea urchins.<sup id="cite_ref-google_87-0" class="reference"><a href="#cite_note-google-87"><span class="cite-bracket">[</span>86<span class="cite-bracket">]</span></a></sup> The coast of Southern California is known as a source of high quality <span title="Japanese-language romanization"><i lang="ja-Latn">uni</i></span>, with divers picking sea urchin from kelp beds in depths as deep as 24 m/80 ft.<sup id="cite_ref-:0_88-0" class="reference"><a href="#cite_note-:0-88"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup> As of 2013, the state was limiting the practice to 300 sea urchin diver licenses.<sup id="cite_ref-:0_88-1" class="reference"><a href="#cite_note-:0-88"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup> Though the edible <i><a href="/wiki/Strongylocentrotus_droebachiensis" title="Strongylocentrotus droebachiensis">Strongylocentrotus droebachiensis</a></i> is found in the North Atlantic, it is not widely eaten. However, sea urchins (called <span title="Alutiiq-language text"><i lang="ems">uutuk</i></span> in <a href="/wiki/Alutiiq_language" title="Alutiiq language">Alutiiq</a>) are commonly eaten by the <a href="/wiki/Alaska_Native" class="mw-redirect" title="Alaska Native">Alaska Native</a> population around <a href="/wiki/Kodiak_Island" title="Kodiak Island">Kodiak Island</a>. It is commonly exported, mostly to <a href="/wiki/Japan" title="Japan">Japan</a>.<sup id="cite_ref-89" class="reference"><a href="#cite_note-89"><span class="cite-bracket">[</span>88<span class="cite-bracket">]</span></a></sup> In the West Indies, <a href="/wiki/Slate_pencil_urchin_(Atlantic)" class="mw-redirect" title="Slate pencil urchin (Atlantic)">slate pencil urchins</a> are eaten.<sup id="cite_ref-Davidson,_Oxford_Companion_72-2" class="reference"><a href="#cite_note-Davidson,_Oxford_Companion-72"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> </p><p>In <a href="/wiki/Chilean_cuisine" title="Chilean cuisine">Chilean cuisine</a>, it is served raw with lemon, onions, and olive oil. </p> <ul class="gallery mw-gallery-packed"> <li class="gallerybox" style="width: 202px"> <div class="thumb" style="width: 200px;"><span typeof="mw:File"><a href="/wiki/File:Unidon_Murakami.jpg" class="mw-file-description" title="Japanese uni-don, or rice bowl with sea urchin roe"><img alt="Japanese uni-don, or rice bowl with sea urchin roe" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Unidon_Murakami.jpg/300px-Unidon_Murakami.jpg" decoding="async" width="200" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Unidon_Murakami.jpg/451px-Unidon_Murakami.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/64/Unidon_Murakami.jpg/600px-Unidon_Murakami.jpg 2x" data-file-width="4032" data-file-height="3024" /></a></span></div> <div class="gallerytext">Japanese <span title="Japanese-language romanization"><i lang="ja-Latn"><a href="/wiki/Donburi" title="Donburi">uni-don</a></i></span>, or rice bowl with sea urchin roe </div> </li> <li class="gallerybox" style="width: 202px"> <div class="thumb" style="width: 200px;"><span typeof="mw:File"><a href="/wiki/File:Sushi_uni.jpg" class="mw-file-description" title="Japanese nigirizushi with sea urchin roe"><img alt="Japanese nigirizushi with sea urchin roe" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/39/Sushi_uni.jpg/330px-Sushi_uni.jpg" decoding="async" width="200" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/39/Sushi_uni.jpg/500px-Sushi_uni.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/39/Sushi_uni.jpg/960px-Sushi_uni.jpg 2x" data-file-width="1600" data-file-height="1200" /></a></span></div> <div class="gallerytext">Japanese <span title="Japanese-language romanization"><i lang="ja-Latn"><a href="/wiki/Nigirizushi" class="mw-redirect" title="Nigirizushi">nigirizushi</a></i></span> with sea urchin roe</div> </li> <li class="gallerybox" style="width: 227.33333333333px"> <div class="thumb" style="width: 225.33333333333px;"><span typeof="mw:File"><a href="/wiki/File:Sushi_Saito_IMG_1773_(23720371141).jpg" class="mw-file-description" title="Sea urchin roe (uni) sashimi"><img alt="Sea urchin roe (uni) sashimi" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Sushi_Saito_IMG_1773_%2823720371141%29.jpg/338px-Sushi_Saito_IMG_1773_%2823720371141%29.jpg" decoding="async" width="226" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Sushi_Saito_IMG_1773_%2823720371141%29.jpg/507px-Sushi_Saito_IMG_1773_%2823720371141%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Sushi_Saito_IMG_1773_%2823720371141%29.jpg/675px-Sushi_Saito_IMG_1773_%2823720371141%29.jpg 2x" data-file-width="4104" data-file-height="2736" /></a></span></div> <div class="gallerytext">Sea urchin roe (<span title="Japanese-language romanization"><i lang="ja-Latn">uni</i></span>) <a href="/wiki/Sashimi" title="Sashimi">sashimi</a></div> </li> <li class="gallerybox" style="width: 155.33333333333px"> <div class="thumb" style="width: 153.33333333333px;"><span typeof="mw:File"><a href="/wiki/File:Fried_rice_with_sea_urchin_1.jpg" class="mw-file-description" title="Fried rice with sea urchin (海胆, hǎidǎn) served in China"><img alt="Fried rice with sea urchin (海胆, hǎidǎn) served in China" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/53/Fried_rice_with_sea_urchin_1.jpg/230px-Fried_rice_with_sea_urchin_1.jpg" decoding="async" width="154" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/53/Fried_rice_with_sea_urchin_1.jpg/346px-Fried_rice_with_sea_urchin_1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/53/Fried_rice_with_sea_urchin_1.jpg/460px-Fried_rice_with_sea_urchin_1.jpg 2x" data-file-width="3472" data-file-height="3394" /></a></span></div> <div class="gallerytext">Fried rice with sea urchin (<span title="Chinese-language text"><span lang="zh">海胆</span></span>, <span title="Chinese-language romanization"><i lang="zh-Latn">hǎidǎn</i></span>) served in China</div> </li> </ul> <div class="mw-heading mw-heading3"><h3 id="Aquaria">Aquaria</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=27" title="Edit section: Aquaria"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Fossil_sea_urchin_(FindID_551527).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Fossil_sea_urchin_%28FindID_551527%29.jpg/220px-Fossil_sea_urchin_%28FindID_551527%29.jpg" decoding="async" width="220" height="135" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Fossil_sea_urchin_%28FindID_551527%29.jpg/330px-Fossil_sea_urchin_%28FindID_551527%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Fossil_sea_urchin_%28FindID_551527%29.jpg/440px-Fossil_sea_urchin_%28FindID_551527%29.jpg 2x" data-file-width="2351" data-file-height="1442" /></a><figcaption>A fossil sea urchin found on a Middle Saxon site in <a href="/wiki/Lincolnshire" title="Lincolnshire">Lincolnshire</a>, thought to have been used as an <a href="/wiki/Amulet" title="Amulet">amulet</a><sup id="cite_ref-90" class="reference"><a href="#cite_note-90"><span class="cite-bracket">[</span>89<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>Some species of sea urchins, such as the slate pencil urchin (<i><a href="/wiki/Eucidaris_tribuloides" title="Eucidaris tribuloides">Eucidaris tribuloides</a></i>), are commonly sold in aquarium stores. Some species are effective at controlling <a href="/wiki/Filamentous_algae" class="mw-redirect" title="Filamentous algae">filamentous algae</a>, and they make good additions to an <a href="/wiki/Invertebrate" title="Invertebrate">invertebrate</a> tank.<sup id="cite_ref-91" class="reference"><a href="#cite_note-91"><span class="cite-bracket">[</span>90<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Folklore">Folklore</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=28" title="Edit section: Folklore"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A folk tradition in Denmark and southern England imagined <a href="/wiki/Fossil_echinoids" title="Fossil echinoids">sea urchin fossils</a> to be thunderbolts, able to ward off harm by lightning or by witchcraft, as an <a href="/wiki/Apotropaic_magic" title="Apotropaic magic">apotropaic symbol</a>.<sup id="cite_ref-92" class="reference"><a href="#cite_note-92"><span class="cite-bracket">[</span>91<span class="cite-bracket">]</span></a></sup> Another version supposed they were petrified eggs of snakes, able to protect against heart and liver disease, poisons, and injury in battle, and accordingly they were carried as <a href="/wiki/Amulet" title="Amulet">amulets</a>. These were, according to the legend, created by magic from foam made by the snakes at midsummer.<sup id="cite_ref-93" class="reference"><a href="#cite_note-93"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Explanatory_notes">Explanatory notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=29" title="Edit section: Explanatory notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text">The tube feet are present in all parts of the animal except around the anus, so technically, the whole surface of the body should be considered to be the oral surface, with the aboral (non-mouth) surface limited to the immediate vicinity of the anus.<sup id="cite_ref-Ruppert_2-2" class="reference"><a href="#cite_note-Ruppert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=30" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626" /><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-adw-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-adw_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://animaldiversity.ummz.umich.edu/site/accounts/information/Echinoidea.html">"Animal Diversity Web – Echinoidea"</a>. University of Michigan Museum of Zoology. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110516154925/http://animaldiversity.ummz.umich.edu/site/accounts/information/Echinoidea.html">Archived</a> from the original on 16 May 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">26 August</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Animal+Diversity+Web+%E2%80%93+Echinoidea&rft.pub=University+of+Michigan+Museum+of+Zoology&rft_id=http%3A%2F%2Fanimaldiversity.ummz.umich.edu%2Fsite%2Faccounts%2Finformation%2FEchinoidea.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-Ruppert-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Ruppert_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Ruppert_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Ruppert_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Ruppert_2-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Ruppert_2-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Ruppert_2-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Ruppert_2-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-Ruppert_2-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-Ruppert_2-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-Ruppert_2-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-Ruppert_2-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-Ruppert_2-11"><sup><i><b>l</b></i></sup></a> <a href="#cite_ref-Ruppert_2-12"><sup><i><b>m</b></i></sup></a> <a href="#cite_ref-Ruppert_2-13"><sup><i><b>n</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFRuppertFoxBarnes2004" class="citation book cs1">Ruppert, Edward E.; Fox, Richard S.; Barnes, Robert D. (2004). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780030259821"><i>Invertebrate Zoology: A Functional Evolutionary Approach</i></a></span> (7th ed.). Belmont, CA: Thomson-Brooks/Cole. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780030259821/page/896/mode/2up">896–906</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0030259827" title="Special:BookSources/0030259827"><bdi>0030259827</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/53021401">53021401</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Invertebrate+Zoology%3A+A+Functional+Evolutionary+Approach&rft.place=Belmont%2C+CA&rft.pages=896-906&rft.edition=7th&rft.pub=Thomson-Brooks%2FCole&rft.date=2004&rft_id=info%3Aoclcnum%2F53021401&rft.isbn=0030259827&rft.aulast=Ruppert&rft.aufirst=Edward+E.&rft.au=Fox%2C+Richard+S.&rft.au=Barnes%2C+Robert+D.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fisbn_9780030259821&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-WoRMS-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-WoRMS_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKroh,_A.Hansson,_H.2013" class="citation web cs1">Kroh, A.; Hansson, H. (2013). <a rel="nofollow" class="external text" href="https://www.marinespecies.org/aphia.php?p=taxdetails&id=123082">"<i>Echinoidea</i> (Leske, 1778)"</a>. <i>WoRMS</i>. <a href="/wiki/World_Register_of_Marine_Species" title="World Register of Marine Species">World Register of Marine Species</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2014-01-04</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=WoRMS&rft.atitle=Echinoidea+%28Leske%2C+1778%29&rft.date=2013&rft.au=Kroh%2C+A.&rft.au=Hansson%2C+H.&rft_id=https%3A%2F%2Fwww.marinespecies.org%2Faphia.php%3Fp%3Dtaxdetails%26id%3D123082&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-IZ-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-IZ_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-IZ_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-IZ_4-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-IZ_4-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-IZ_4-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-IZ_4-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-IZ_4-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-IZ_4-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-IZ_4-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-IZ_4-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-IZ_4-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-IZ_4-11"><sup><i><b>l</b></i></sup></a> <a href="#cite_ref-IZ_4-12"><sup><i><b>m</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBarnes1982" class="citation book cs1">Barnes, Robert D. 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Philadelphia, PA: Holt-Saunders International. pp. <span class="nowrap">961–</span>981. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-03-056747-5" title="Special:BookSources/0-03-056747-5"><bdi>0-03-056747-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Invertebrate+Zoology&rft.place=Philadelphia%2C+PA&rft.pages=%3Cspan+class%3D%22nowrap%22%3E961-%3C%2Fspan%3E981&rft.pub=Holt-Saunders+International&rft.date=1982&rft.isbn=0-03-056747-5&rft.aulast=Barnes&rft.aufirst=Robert+D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFGuill,_Michael" class="citation web cs1">Guill, Michael. <a rel="nofollow" class="external text" href="http://www.tulane.edu/~bwee/eeb111/GreekLatin%20Roots.html">"Taxonomic Etymologies EEOB 111"</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20240517161239/https://www2.tulane.edu/~bwee/eeb111/GreekLatin%20Roots.html">Archived</a> from the original on 17 May 2024<span class="reference-accessdate">. Retrieved <span class="nowrap">13 March</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Taxonomic+Etymologies+EEOB+111&rft.au=Guill%2C+Michael&rft_id=http%3A%2F%2Fwww.tulane.edu%2F~bwee%2Feeb111%2FGreekLatin%2520Roots.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">Wright, Anne. 1851. <i>The Observing Eye, Or, Letters to Children on the Three Lowest Divisions of Animal Life.</i> London: Jarrold and Sons, p. 107.</span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><a href="/wiki/Soyer,_Alexis" class="mw-redirect" title="Soyer, Alexis">Soyer, Alexis</a>. 1853. <i>The Pantropheon Or History of Food, And Its Preparation: From The Earliest Ages Of The World.</i> Boston: Ticknor, Reed, and Fields, p. 245.</span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation encyclopaedia cs1"><a rel="nofollow" class="external text" href="https://www.etymonline.com/word/urchin">"urchin (n.)"</a>. <i>Online Etymology Dictionary</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180315070539/https://www.etymonline.com/word/urchin">Archived</a> from the original on 15 March 2018<span class="reference-accessdate">. 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Retrieved <span class="nowrap">28 December</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.nhm.ac.uk&rft.atitle=The+Echinoid+Directory+%E2%80%93+Natural+History+Museum&rft_id=https%3A%2F%2Fwww.nhm.ac.uk%2Four-science%2Fdata%2Fechinoid-directory%2Fmorphology%2Fregulars%2Fintro.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.nhm.ac.uk/our-science/data/echinoid-directory/morphology/regulars/intro.html">"The Echinoid Directory – Natural History Museum"</a>. <i>www.nhm.ac.uk</i>. Natural History Museum, UK. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20231208134929/https://www.nhm.ac.uk/our-science/data/echinoid-directory/morphology/regulars/intro.html">Archived</a> from the original on 8 December 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">28 December</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.nhm.ac.uk&rft.atitle=The+Echinoid+Directory+%E2%80%93+Natural+History+Museum&rft_id=https%3A%2F%2Fwww.nhm.ac.uk%2Four-science%2Fdata%2Fechinoid-directory%2Fmorphology%2Fregulars%2Fintro.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.gizmag.com/carbon-capture-calcium-carbonate/26101/">"Sea urchins reveal promising carbon capture alternative"</a>. Gizmag. 4 February 2013. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160714210351/http://www.gizmag.com/carbon-capture-calcium-carbonate/26101/">Archived</a> from the original on 2016-07-14<span class="reference-accessdate">. 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"Crinoid Ecological Morphology". <i>Annual Review of Earth and Planetary Sciences</i>. <b>36</b>: <span class="nowrap">221–</span>49. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2008AREPS..36..221B">2008AREPS..36..221B</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1146%2Fannurev.earth.36.031207.124116">10.1146/annurev.earth.36.031207.124116</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annual+Review+of+Earth+and+Planetary+Sciences&rft.atitle=Crinoid+Ecological+Morphology&rft.volume=36&rft.pages=%3Cspan+class%3D%22nowrap%22%3E221-%3C%2Fspan%3E49&rft.date=2008&rft_id=info%3Adoi%2F10.1146%2Fannurev.earth.36.031207.124116&rft_id=info%3Abibcode%2F2008AREPS..36..221B&rft.aulast=Baumiller&rft.aufirst=Tomasz+K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-Lawrence-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-Lawrence_31-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLawrence,_John_M.2006" class="citation book cs1">Lawrence, John M. (2006). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=6T2JomruARoC"><i>Edible Sea Urchins: Biology and Ecology</i></a>. Elsevier. pp. <span class="nowrap">167–</span>168. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-08-046558-6" title="Special:BookSources/978-0-08-046558-6"><bdi>978-0-08-046558-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Edible+Sea+Urchins%3A+Biology+and+Ecology&rft.pages=%3Cspan+class%3D%22nowrap%22%3E167-%3C%2Fspan%3E168&rft.pub=Elsevier&rft.date=2006&rft.isbn=978-0-08-046558-6&rft.au=Lawrence%2C+John+M.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D6T2JomruARoC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFJangoux,_Michel1987" class="citation journal cs1">Jangoux, Michel (1987). <a rel="nofollow" class="external text" href="https://doi.org/10.3354%2Fdao002147">"Diseases of Echinodermata. I. Agents microorganisms and protistans"</a>. <i>Diseases of Aquatic Organisms</i>. <b>2</b>: <span class="nowrap">147–</span>162. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.3354%2Fdao002147">10.3354/dao002147</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Diseases+of+Aquatic+Organisms&rft.atitle=Diseases+of+Echinodermata.+I.+Agents+microorganisms+and+protistans&rft.volume=2&rft.pages=%3Cspan+class%3D%22nowrap%22%3E147-%3C%2Fspan%3E162&rft.date=1987&rft_id=info%3Adoi%2F10.3354%2Fdao002147&rft.au=Jangoux%2C+Michel&rft_id=https%3A%2F%2Fdoi.org%2F10.3354%252Fdao002147&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-Defence_–_spines-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-Defence_–_spines_33-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/intro/defence1.html">"Defence – spines"</a>. <i>Echinoid Directory</i>. <a href="/wiki/Natural_History_Museum,_London" title="Natural History Museum, London">Natural History Museum</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Echinoid+Directory&rft.atitle=Defence+%E2%80%93+spines&rft_id=http%3A%2F%2Fwww.nhm.ac.uk%2Fresearch-curation%2Fresearch%2Fprojects%2Fechinoid-directory%2Fintro%2Fdefence1.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFSakashita,_Hiroko1992" class="citation journal cs1">Sakashita, Hiroko (1992). "Sexual dimorphism and food habits of the clingfish, <i>Diademichthys lineatus</i>, and its dependence on host sea urchin". <i>Environmental Biology of Fishes</i>. <b>34</b> (1): <span class="nowrap">95–</span>101. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1992EnvBF..34...95S">1992EnvBF..34...95S</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF00004787">10.1007/BF00004787</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:32656986">32656986</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Environmental+Biology+of+Fishes&rft.atitle=Sexual+dimorphism+and+food+habits+of+the+clingfish%2C+Diademichthys+lineatus%2C+and+its+dependence+on+host+sea+urchin&rft.volume=34&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E95-%3C%2Fspan%3E101&rft.date=1992&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A32656986%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1007%2FBF00004787&rft_id=info%3Abibcode%2F1992EnvBF..34...95S&rft.au=Sakashita%2C+Hiroko&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFTerborgh,_JohnEstes,_James_A2013" class="citation book cs1">Terborgh, John; Estes, James A (2013). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=tjOT8KJ6mF8C&pg=PA38"><i>Trophic Cascades: Predators, Prey, and the Changing Dynamics of Nature</i></a>. Island Press. p. 38. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-59726-819-6" title="Special:BookSources/978-1-59726-819-6"><bdi>978-1-59726-819-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Trophic+Cascades%3A+Predators%2C+Prey%2C+and+the+Changing+Dynamics+of+Nature&rft.pages=38&rft.pub=Island+Press&rft.date=2013&rft.isbn=978-1-59726-819-6&rft.au=Terborgh%2C+John&rft.au=Estes%2C+James+A&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DtjOT8KJ6mF8C%26pg%3DPA38&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-dfo-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-dfo_36-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080123224702/http://www.dfo-mpo.gc.ca/species-especes/species/species_seaOtter_e.asp">"Aquatic Species at Risk – Species Profile – Sea Otter"</a>. <a href="/wiki/Fisheries_and_Oceans_Canada" title="Fisheries and Oceans Canada">Fisheries and Oceans Canada</a>. Archived from <a rel="nofollow" class="external text" href="http://www.dfo-mpo.gc.ca/species-especes/species/species_seaOtter_e.asp">the original</a> on 2008-01-23<span class="reference-accessdate">. Retrieved <span class="nowrap">2007-11-29</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Aquatic+Species+at+Risk+%E2%80%93+Species+Profile+%E2%80%93+Sea+Otter&rft.pub=Fisheries+and+Oceans+Canada&rft_id=http%3A%2F%2Fwww.dfo-mpo.gc.ca%2Fspecies-especes%2Fspecies%2Fspecies_seaOtter_e.asp&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-Thiel-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-Thiel_37-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFThiel,_MartinWatling,_Les2015" class="citation book cs1">Thiel, Martin; Watling, Les (2015). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=RZ-eBgAAQBAJ&pg=PA200"><i>Lifestyles and Feeding Biology</i></a>. Oxford University Press. pp. <span class="nowrap">200–</span>202. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-979702-8" title="Special:BookSources/978-0-19-979702-8"><bdi>978-0-19-979702-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Lifestyles+and+Feeding+Biology&rft.pages=%3Cspan+class%3D%22nowrap%22%3E200-%3C%2Fspan%3E202&rft.pub=Oxford+University+Press&rft.date=2015&rft.isbn=978-0-19-979702-8&rft.au=Thiel%2C+Martin&rft.au=Watling%2C+Les&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DRZ-eBgAAQBAJ%26pg%3DPA200&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/intro/defence3.html">"Defence – pedicellariae"</a>. <i>Echinoid Directory</i>. <a href="/wiki/Natural_History_Museum,_London" title="Natural History Museum, London">Natural History Museum</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141006072057/http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/intro/defence3.html">Archived</a> from the original on 2014-10-06<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-08-04</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Echinoid+Directory&rft.atitle=Defence+%E2%80%93+pedicellariae&rft_id=http%3A%2F%2Fwww.nhm.ac.uk%2Fresearch-curation%2Fresearch%2Fprojects%2Fechinoid-directory%2Fintro%2Fdefence3.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text">Hiroko Sakashita, " Sexual dimorphism and food habits of the clingfish, Diademichthys lineatus, and its dependence on host sea urchin ", Environmental Biology of Fishes, vol. 34, no 1, 1994, p. 95–101</span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFJangoux,_M.1984" class="citation journal cs1">Jangoux, M. 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Retrieved <span class="nowrap">10 September</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Hakai+Magazine&rft.atitle=Searchin%27+for+Urchin%3A+A+Culinary+Quest&rft.date=2018-09-06&rft.aulast=Zatylny&rft.aufirst=Jane&rft_id=https%3A%2F%2Fwww.hakaimagazine.com%2Ffeatures%2Fsearchin-for-urchin-a-culinary-quest%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-77"><span class="mw-cite-backlink"><b><a href="#cite_ref-77">^</a></b></span> <span class="reference-text">"Sea Urchin Fishery and Overfishing", <i>TED Case Studies</i> <b>296</b>, American University <a rel="nofollow" class="external text" href="http://www.american.edu/TED/urchin.htm">full text</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20090628151427/http://www1.american.edu/TED/urchin.HTM">Archived</a> 2009-06-28 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-kso_1-78"><span class="mw-cite-backlink"><b><a href="#cite_ref-kso_1_78-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://sinama.org/2013/06/making-oko-oko-a-sama-sea-urchin-delicacy/">"Making Oko'-Oko', A Sama Sea Urchin Delicacy"</a>. <i>Kauman Sama Online</i>. 27 June 2013. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230603025132/https://sinama.org/2013/06/making-oko-oko-a-sama-sea-urchin-delicacy/">Archived</a> from the original on 3 June 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">3 June</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Kauman+Sama+Online&rft.atitle=Making+Oko%27-Oko%27%2C+A+Sama+Sea+Urchin+Delicacy&rft.date=2013-06-27&rft_id=https%3A%2F%2Fsinama.org%2F2013%2F06%2Fmaking-oko-oko-a-sama-sea-urchin-delicacy%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-79"><span class="mw-cite-backlink"><b><a href="#cite_ref-79">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKhir_Johari2021" class="citation magazine cs1">Khir Johari (Oct–Dec 2021). <a rel="nofollow" class="external text" href="https://biblioasia.nlb.gov.sg/vol-17/issue-3/oct-dec-2021/">"The Role of Foraging in Malay Cuisine"</a>. <i>BiblioAsia</i>. Vol. 17, no. 3. National Library Board, Singapore. pp. <span class="nowrap">20–</span>23. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20231106234414/https://biblioasia.nlb.gov.sg/vol-17/issue-3/oct-dec-2021/">Archived</a> from the original on 2023-11-06<span class="reference-accessdate">. Retrieved <span class="nowrap">2023-02-01</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=BiblioAsia&rft.atitle=The+Role+of+Foraging+in+Malay+Cuisine&rft.volume=17&rft.issue=3&rft.pages=%3Cspan+class%3D%22nowrap%22%3E20-%3C%2Fspan%3E23&rft.date=2021-10%2F2021-12&rft.au=Khir+Johari&rft_id=https%3A%2F%2Fbiblioasia.nlb.gov.sg%2Fvol-17%2Fissue-3%2Foct-dec-2021%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-80"><span class="mw-cite-backlink"><b><a href="#cite_ref-80">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFWassilieff2009" class="citation encyclopaedia cs1">Wassilieff, Maggy (March 2, 2009). <a rel="nofollow" class="external text" href="https://www.teara.govt.nz/en/starfish-sea-urchins-and-other-echinoderms/2">"sea urchins"</a>. <i><a href="/wiki/Te_Ara:_The_Encyclopedia_of_New_Zealand" title="Te Ara: The Encyclopedia of New Zealand">Te Ara: The Encyclopedia of New Zealand</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20101025163949/http://www.teara.govt.nz/en/starfish-sea-urchins-and-other-echinoderms/2">Archived</a> from the original on October 25, 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">October 8,</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=sea+urchins&rft.btitle=Te+Ara%3A+The+Encyclopedia+of+New+Zealand&rft.date=2009-03-02&rft.aulast=Wassilieff&rft.aufirst=Maggy&rft_id=http%3A%2F%2Fwww.teara.govt.nz%2Fen%2Fstarfish-sea-urchins-and-other-echinoderms%2F2&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-81"><span class="mw-cite-backlink"><b><a href="#cite_ref-81">^</a></b></span> <span class="reference-text">for Puglia, Italy: Touring Club Italiano, <i>Guida all'Italia gastronomica</i>, 1984, p. 314; for Alexandria, Egypt: <a href="/wiki/Claudia_Roden" title="Claudia Roden">Claudia Roden</a>, <i>A Book of Middle Eastern Food</i>, p. 183</span> </li> <li id="cite_note-82"><span class="mw-cite-backlink"><b><a href="#cite_ref-82">^</a></b></span> <span class="reference-text"><a href="/wiki/Alan_Davidson_(food_writer)" title="Alan Davidson (food writer)">Alan Davidson</a>, <i>Mediterranean Seafood</i>, p. 270</span> </li> <li id="cite_note-83"><span class="mw-cite-backlink"><b><a href="#cite_ref-83">^</a></b></span> <span class="reference-text"><a href="/wiki/Larousse_Gastronomique" title="Larousse Gastronomique">Larousse Gastronomique</a><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (November 2010)">page needed</span></a></i>]</sup></span> </li> <li id="cite_note-84"><span class="mw-cite-backlink"><b><a href="#cite_ref-84">^</a></b></span> <span class="reference-text"><a href="/wiki/Curnonsky" title="Curnonsky">Curnonsky</a>, <i>Cuisine et vins de France</i>, nouvelle édition, 1974, p. 248</span> </li> <li id="cite_note-85"><span class="mw-cite-backlink"><b><a href="#cite_ref-85">^</a></b></span> <span class="reference-text">Davidson, Alan (2014) <i><a href="/wiki/Oxford_Companion_to_Food" class="mw-redirect" title="Oxford Companion to Food">Oxford Companion to Food</a></i>. <a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a>, 3rd edition. p. 280</span> </li> <li id="cite_note-86"><span class="mw-cite-backlink"><b><a href="#cite_ref-86">^</a></b></span> <span class="reference-text">Every year, 'oursinades' (sea urchin festivals) are held in and around Marseille to promote this 'sea hedgehog <a rel="nofollow" class="external free" href="https://www.marseille-tourisme.com/en/discover-marseille/gastronomy-in-marseille/culinary-specialities-of-marseille/the-oursinades-in-marseille/">https://www.marseille-tourisme.com/en/discover-marseille/gastronomy-in-marseille/culinary-specialities-of-marseille/the-oursinades-in-marseille/</a></span> </li> <li id="cite_note-google-87"><span class="mw-cite-backlink"><b><a href="#cite_ref-google_87-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFMartin,_R.E.Carter,_E.P.Flick,_G.J.Davis,_L.M.2000" class="citation book cs1">Martin, R.E.; Carter, E.P.; Flick, G.J.; Davis, L.M. (2000). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=OFKLk3S0fzgC"><i>Marine and Freshwater Products Handbook</i></a>. Taylor & Francis. p. 268. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-56676-889-4" title="Special:BookSources/978-1-56676-889-4"><bdi>978-1-56676-889-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20240825043715/https://books.google.com/books?id=OFKLk3S0fzgC">Archived</a> from the original on 2024-08-25<span class="reference-accessdate">. Retrieved <span class="nowrap">2014-12-03</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marine+and+Freshwater+Products+Handbook&rft.pages=268&rft.pub=Taylor+%26+Francis&rft.date=2000&rft.isbn=978-1-56676-889-4&rft.au=Martin%2C+R.E.&rft.au=Carter%2C+E.P.&rft.au=Flick%2C+G.J.&rft.au=Davis%2C+L.M.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DOFKLk3S0fzgC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-:0-88"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_88-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_88-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFLam2014" class="citation news cs1">Lam, Francis (2014-03-14). <a rel="nofollow" class="external text" href="http://www.bonappetit.com/people/article/california-sea-urchin-divers-interviewed-by-francis-lam">"California Sea Urchin Divers, Interviewed by Francis Lam"</a>. <i>Bon Appetit</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170326231148/http://www.bonappetit.com/people/article/california-sea-urchin-divers-interviewed-by-francis-lam">Archived</a> from the original on 2017-03-26<span class="reference-accessdate">. Retrieved <span class="nowrap">2017-03-26</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bon+Appetit&rft.atitle=California+Sea+Urchin+Divers%2C+Interviewed+by+Francis+Lam&rft.date=2014-03-14&rft.aulast=Lam&rft.aufirst=Francis&rft_id=http%3A%2F%2Fwww.bonappetit.com%2Fpeople%2Farticle%2Fcalifornia-sea-urchin-divers-interviewed-by-francis-lam&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-89"><span class="mw-cite-backlink"><b><a href="#cite_ref-89">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKleiman1990" class="citation news cs1">Kleiman, Dena (October 3, 1990). <a rel="nofollow" class="external text" href="https://www.nytimes.com/1990/10/03/garden/scorned-at-home-maine-sea-urchin-is-a-star-in-japan.html">"Scorned at Home, Maine Sea Urchin Is a Star in Japan"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>. p. C1. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170202001653/http://www.nytimes.com/1990/10/03/garden/scorned-at-home-maine-sea-urchin-is-a-star-in-japan.html">Archived</a> from the original on February 2, 2017<span class="reference-accessdate">. Retrieved <span class="nowrap">February 12,</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+New+York+Times&rft.atitle=Scorned+at+Home%2C+Maine+Sea+Urchin+Is+a+Star+in+Japan&rft.pages=C1&rft.date=1990-10-03&rft.aulast=Kleiman&rft.aufirst=Dena&rft_id=https%3A%2F%2Fwww.nytimes.com%2F1990%2F10%2F03%2Fgarden%2Fscorned-at-home-maine-sea-urchin-is-a-star-in-japan.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-90"><span class="mw-cite-backlink"><b><a href="#cite_ref-90">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://finds.org.uk/database/artefacts/record/id/551527">"Amulet | LIN-B37563"</a>. <i>Portable Antiquities Scheme</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180315070608/https://finds.org.uk/database/artefacts/record/id/551527">Archived</a> from the original on 15 March 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">14 March</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Portable+Antiquities+Scheme&rft.atitle=Amulet+%7C+LIN-B37563&rft_id=https%3A%2F%2Ffinds.org.uk%2Fdatabase%2Fartefacts%2Frecord%2Fid%2F551527&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-91"><span class="mw-cite-backlink"><b><a href="#cite_ref-91">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFTullock2008" class="citation book cs1">Tullock, John H. (2008). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/yourfirstmarinea0000tull"><i>Your First Marine Aquarium: Everything about Setting Up a Marine Aquarium, Including Conditioning, Maintenance, Selecting Fish and Invertebrates, and More</i></a></span>. Barron's Educational Series. p. <a rel="nofollow" class="external text" href="https://archive.org/details/yourfirstmarinea0000tull/page/63">63</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7641-3675-7" title="Special:BookSources/978-0-7641-3675-7"><bdi>978-0-7641-3675-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Your+First+Marine+Aquarium%3A+Everything+about+Setting+Up+a+Marine+Aquarium%2C+Including+Conditioning%2C+Maintenance%2C+Selecting+Fish+and+Invertebrates%2C+and+More&rft.pages=63&rft.pub=Barron%27s+Educational+Series&rft.date=2008&rft.isbn=978-0-7641-3675-7&rft.aulast=Tullock&rft.aufirst=John+H.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fyourfirstmarinea0000tull&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-92"><span class="mw-cite-backlink"><b><a href="#cite_ref-92">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFMcNamara2012" class="citation web cs1">McNamara, Ken (2012). <a rel="nofollow" class="external text" href="https://www.geolsoc.org.uk/Geoscientist/Archive/June-2012/Prehistoric-fossil-collectors">"Prehistoric fossil collectors"</a>. The Geological Society. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190217090444/https://www.geolsoc.org.uk/Geoscientist/Archive/June-2012/Prehistoric-fossil-collectors">Archived</a> from the original on 17 February 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">14 March</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Prehistoric+fossil+collectors&rft.pub=The+Geological+Society&rft.date=2012&rft.aulast=McNamara&rft.aufirst=Ken&rft_id=https%3A%2F%2Fwww.geolsoc.org.uk%2FGeoscientist%2FArchive%2FJune-2012%2FPrehistoric-fossil-collectors&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> <li id="cite_note-93"><span class="mw-cite-backlink"><b><a href="#cite_ref-93">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFMarren,_PeterMabey,_Richard2010" class="citation book cs1"><a href="/wiki/Peter_Marren" title="Peter Marren">Marren, Peter</a>; <a href="/wiki/Richard_Mabey" title="Richard Mabey">Mabey, Richard</a> (2010). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Ah62bUZLDOwC"><i>Bugs Britannica</i></a>. Chatto & Windus. pp. <span class="nowrap">469–</span>470. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7011-8180-2" title="Special:BookSources/978-0-7011-8180-2"><bdi>978-0-7011-8180-2</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230728001019/https://books.google.com/books?id=Ah62bUZLDOwC">Archived</a> from the original on 2023-07-28<span class="reference-accessdate">. Retrieved <span class="nowrap">2018-03-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Bugs+Britannica&rft.pages=%3Cspan+class%3D%22nowrap%22%3E469-%3C%2Fspan%3E470&rft.pub=Chatto+%26+Windus&rft.date=2010&rft.isbn=978-0-7011-8180-2&rft.au=Marren%2C+Peter&rft.au=Mabey%2C+Richard&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DAh62bUZLDOwC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASea+urchin" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sea_urchin&action=edit&section=31" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid 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screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/40px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/60px-Commons-logo.svg.png 1.5x" data-file-width="1024" data-file-height="1376" /></a></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Echinoidea" class="extiw" title="commons:Category:Echinoidea">Echinoidea</a></span>.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="http://www.marinespecies.org">World Register of Marine Species link</a>: <a rel="nofollow" class="external text" href="http://www.marinespecies.org/aphia.php?p=taxdetails&id=123082"><i>Echinoidea</i> Leske, 1778</a> (<small><a rel="nofollow" class="external text" href="http://www.marinespecies.org/aphia.php?p=taxlist&rComp==&tRank=220&vOnly=yes&marine=no&pid=123082">+species list</a></small>)</li> <li><a rel="nofollow" class="external text" href="https://archive.today/20121228104735/http://spbase.org/">The sea urchin genome project</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20070827120312/http://www.seaurchin.org/">Sea Urchin Harvesters Association – California</a> Also, (604) 524-0322.</li> <li><a rel="nofollow" class="external text" href="http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/">The Echinoid Directory</a> from the <a href="/wiki/Natural_History_Museum,_London" title="Natural History Museum, London">Natural History Museum</a>.</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100723152249/http://virtualurchin.stanford.edu/urchinanatomy.swf">Virtual Urchin</a> at Stanford</li> <li><a rel="nofollow" class="external text" href="http://www.calurchin.org/index.html">California Sea Urchin commission</a></li> <li><a rel="nofollow" class="external text" href="http://www.ucmp.berkeley.edu/echinodermata/echinoidea.html">Introduction to the Echinoidea</a> at UCMP Berkeley</li></ul> <div class="navbox-styles"><style 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species groups</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wild_fisheries" title="Wild fisheries">Wild</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Pelagic_fish" title="Pelagic fish">Large pelagic fish</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mackerel" title="Mackerel">Mackerel</a></li> <li><a href="/wiki/Salmon" title="Salmon">Salmon</a></li> <li><a href="/wiki/Shark" title="Shark">Shark</a></li> <li><a href="/wiki/Swordfish" title="Swordfish">Swordfish</a></li> <li><a href="/wiki/Tuna" title="Tuna">Tuna</a> <ul><li><a href="/wiki/Albacore" title="Albacore">albacore</a></li> <li><a href="/wiki/Bigeye_tuna" title="Bigeye tuna">bigeye</a></li> <li><a href="/wiki/Atlantic_bluefin_tuna" title="Atlantic bluefin tuna">Atlantic bluefin</a></li> <li><a href="/wiki/Pacific_bluefin_tuna" title="Pacific bluefin tuna">Pacific bluefin</a></li> <li><a href="/wiki/Southern_bluefin_tuna" title="Southern bluefin tuna">southern bluefin</a></li> <li><a href="/wiki/Skipjack_tuna" title="Skipjack tuna">skipjack</a></li> <li><a href="/wiki/Yellowfin_tuna" title="Yellowfin tuna">yellowfin</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Forage_fish" title="Forage fish">Forage fish</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anchovy" title="Anchovy">Anchovy</a></li> <li><a href="/wiki/Capelin" title="Capelin">Capelin</a></li> <li><a href="/wiki/Herring" title="Herring">Herring</a></li> <li><a href="/wiki/Ilish" title="Ilish">Ilish</a></li> <li><a href="/wiki/Menhaden" title="Menhaden">Menhaden</a></li> <li><a href="/wiki/Sardine" title="Sardine">Sardines</a></li> <li><a href="/wiki/Pacific_saury" title="Pacific saury">Saury</a></li> <li><a href="/wiki/Shad" class="mw-redirect" title="Shad">Shad</a></li> <li><a href="/wiki/Sprat" title="Sprat">Sprat</a> <ul><li><a href="/wiki/European_sprat" title="European sprat">european</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Demersal_fish" title="Demersal fish">Demersal fish</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Catfish" title="Catfish">Catfish</a></li> <li><a href="/wiki/Cod" title="Cod">Cod</a> <ul><li><a href="/wiki/Atlantic_cod" title="Atlantic cod">Atlantic</a></li> <li><a href="/wiki/Pacific_cod" title="Pacific cod">Pacific</a></li> <li><a href="/wiki/Alaska_pollock" title="Alaska pollock">Alaska pollock</a></li></ul></li> <li><a href="/wiki/Flatfish" title="Flatfish">Flatfish</a> <ul><li><a href="/wiki/Flounder" title="Flounder">flounder</a></li> <li><a href="/wiki/Halibut" title="Halibut">halibut</a></li> <li><a href="/wiki/Plaice" title="Plaice">plaice</a></li> <li><a href="/wiki/Sole_(fish)" title="Sole (fish)">sole</a></li> <li><a href="/wiki/Turbot" title="Turbot">turbot</a></li></ul></li> <li><a href="/wiki/Haddock" title="Haddock">Haddock</a></li> <li><a href="/wiki/Mullet_(fish)" title="Mullet (fish)">Mullet</a></li> <li><a href="/wiki/Orange_roughy" title="Orange roughy">Orange roughy</a></li> <li><a href="/wiki/Pollock" title="Pollock">Pollock</a></li> <li><a href="/wiki/Sebastes" title="Sebastes">Rockfish</a></li> <li><a href="/wiki/Sillaginidae" title="Sillaginidae">Smelt-whitings</a></li> <li><a href="/wiki/Toothfish" class="mw-redirect" title="Toothfish">Toothfish</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Freshwater_fish" title="Freshwater fish">Freshwater fish</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Carp" title="Carp">Carp</a></li> <li><a href="/wiki/Sturgeon" title="Sturgeon">Sturgeon</a></li> <li><a href="/wiki/Tilapia" title="Tilapia">Tilapia</a></li> <li><a href="/wiki/Trout" title="Trout">Trout</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wild_fish" class="mw-redirect" title="Wild fish">Other wild fish</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Eel" title="Eel">Eel</a></li> <li><a href="/wiki/Whitebait" title="Whitebait">Whitebait</a></li> <li><a href="/wiki/Category:Commercial_fish" title="Category:Commercial fish">more...</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Crustacean" title="Crustacean">Crustaceans</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Crab" title="Crab">Crab</a></li> <li><a href="/wiki/Krill" title="Krill">Krill</a></li> <li><a href="/wiki/Lobster" title="Lobster">Lobster</a></li> <li><a href="/wiki/Shrimp" title="Shrimp">Shrimp</a> <ul><li><a href="/wiki/Prawn" title="Prawn">Prawns</a></li></ul></li> <li><a href="/wiki/Category:Commercial_crustaceans" title="Category:Commercial crustaceans">more...</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Mollusc" class="mw-redirect" title="Mollusc">Molluscs</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Abalone" title="Abalone">Abalone</a></li> <li><a href="/wiki/Mussel" title="Mussel">Mussels</a></li> <li><a href="/wiki/Octopus" title="Octopus">Octopus</a></li> <li><a href="/wiki/Oyster" title="Oyster">Oysters</a></li> <li><a href="/wiki/Scallop" title="Scallop">Scallops</a></li> <li><a href="/wiki/Squid" title="Squid">Squid</a></li> <li><a href="/wiki/Category:Commercial_molluscs" title="Category:Commercial molluscs">more...</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Echinoderm" title="Echinoderm">Echinoderms</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Sea_cucumber" title="Sea cucumber">Sea cucumbers</a></li> <li><a class="mw-selflink selflink">Sea urchin</a></li> <li><a href="/wiki/Category:Commercial_echinoderms" title="Category:Commercial echinoderms">more...</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fisheries</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cod_fisheries" title="Cod fisheries">Cod fisheries</a></li> <li><a href="/wiki/Crab_fisheries" title="Crab fisheries">Crab fisheries</a></li> <li><a href="/wiki/Krill_fishery" title="Krill fishery">Krill fishery</a></li> <li><a href="/wiki/Lobster_fishing" title="Lobster fishing">Lobster fishing</a></li> <li><a href="/wiki/Shrimp_fishery" title="Shrimp fishery">Shrimp fishery</a></li></ul> </div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="2" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/File:Atlantic_cod.jpg" class="mw-file-description" title="Atlantic cod"><img alt="Atlantic cod" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Atlantic_cod.jpg/140px-Atlantic_cod.jpg" decoding="async" width="140" height="60" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Atlantic_cod.jpg/210px-Atlantic_cod.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Atlantic_cod.jpg/280px-Atlantic_cod.jpg 2x" data-file-width="600" data-file-height="255" /></a></span><br /><br /><span typeof="mw:File"><a href="/wiki/File:Lobster_(PSF).png" class="mw-file-description" title="Lobster"><img alt="Lobster" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Lobster_%28PSF%29.png/100px-Lobster_%28PSF%29.png" decoding="async" width="100" height="62" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Lobster_%28PSF%29.png/150px-Lobster_%28PSF%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Lobster_%28PSF%29.png/200px-Lobster_%28PSF%29.png 2x" data-file-width="2821" data-file-height="1748" /></a></span><br /><br /><span typeof="mw:File"><a href="/wiki/File:Pacific_oysters_01.jpg" class="mw-file-description" title="Pacific oysters"><img alt="Pacific oysters" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Pacific_oysters_01.jpg/120px-Pacific_oysters_01.jpg" decoding="async" width="80" height="59" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Pacific_oysters_01.jpg/250px-Pacific_oysters_01.jpg 2x" data-file-width="1750" data-file-height="1282" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aquaculture" title="Aquaculture">Farmed</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Carp#Aquaculture" title="Carp">Carp</a> <ul><li><a href="/wiki/Bighead_carp" title="Bighead carp">bighead</a></li> <li><a href="/wiki/Common_carp" title="Common carp">common</a></li> <li><a href="/wiki/Crucian_carp" title="Crucian carp">crucian</a></li> <li><a href="/wiki/Grass_carp" title="Grass carp">grass</a></li> <li><a href="/wiki/Silver_carp" title="Silver carp">silver</a></li></ul></li> <li><a href="/wiki/Aquaculture_of_catfish" title="Aquaculture of catfish">Catfish</a></li> <li><a href="/wiki/Freshwater_prawn_farming" title="Freshwater prawn farming">Freshwater prawns</a></li> <li><a href="/wiki/Gilt-head_bream" title="Gilt-head bream">Gilt-head bream</a></li> <li><a href="/wiki/Mussel#Aquaculture" title="Mussel">Mussels</a></li> <li><a href="/wiki/Oyster_farming" title="Oyster farming">Oysters</a></li> <li><a href="/wiki/Aquaculture_of_salmon" class="mw-redirect" title="Aquaculture of salmon">Salmon</a> <ul><li><a href="/wiki/Atlantic_salmon" title="Atlantic salmon">Atlantic</a></li> <li><a href="/wiki/Rainbow_trout" title="Rainbow trout">salmon trout</a></li> <li><a href="/wiki/Coho_salmon" title="Coho salmon">coho</a></li> <li><a href="/wiki/Chinook_salmon" title="Chinook salmon">chinook</a></li></ul></li> <li><a href="/wiki/Scallop_aquaculture" title="Scallop aquaculture">Scallops</a></li> <li><a href="/wiki/Seaweed_farming" title="Seaweed farming">Seaweed</a></li> <li><a href="/wiki/Marine_shrimp_farming" title="Marine shrimp farming">Shrimp</a></li> <li><a href="/wiki/Aquaculture_of_tilapia" title="Aquaculture of tilapia">Tilapia</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div> <ul><li><a href="/wiki/Commercial_fishing" title="Commercial fishing">Commercial fishing</a></li> <li><a href="/wiki/World_fish_production" class="mw-redirect" title="World fish production">World fish production</a></li> <li><a href="/wiki/List_of_commercially_important_fish_species" title="List of commercially important fish species">Commercial species</a></li> <li><a href="/wiki/List_of_fishing_topics_by_subject" class="mw-redirect" title="List of fishing topics by subject">Fishing topics</a></li> <li><a href="/wiki/Fisheries_glossary" class="mw-redirect" title="Fisheries glossary">Fisheries glossary</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374" /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235" /></div><div role="navigation" class="navbox" aria-labelledby="Taxon_identifiers3046" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Taxon_identifiers3046" style="font-size:114%;margin:0 4em"><a href="/wiki/Help:Taxon_identifiers" title="Help:Taxon identifiers">Taxon identifiers</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: left;"><i>Echinoidea</i></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><span style="white-space:nowrap;"><a href="/wiki/Wikidata" title="Wikidata">Wikidata</a>: <span class="uid"><span class="external"><a href="https://www.wikidata.org/wiki/Q83483" class="extiw" title="wikidata:Q83483">Q83483</a></span></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Wikispecies" title="Wikispecies">Wikispecies</a>: <span class="uid"><span class="external"><a href="https://species.wikimedia.org/wiki/Echinoidea" class="extiw" title="wikispecies:Echinoidea">Echinoidea</a></span></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Animal_Diversity_Web" title="Animal Diversity Web">ADW</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://animaldiversity.org/accounts/Echinoidea/">Echinoidea</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Australian_Faunal_Directory" title="Australian Faunal Directory">AFD</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://biodiversity.org.au/afd/taxa/Echinoidea">Echinoidea</a></span></span></li> <li><span style="white-space:nowrap;">BioLib: <span class="uid"><a rel="nofollow" class="external text" href="https://www.biolib.cz/en/taxon/id80056">80056</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Barcode_of_Life_Data_System" title="Barcode of Life Data System">BOLD</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://bench.boldsystems.org/index.php/TaxBrowser_TaxonPage?taxid=29">29</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Catalogue_of_Life" title="Catalogue of Life">CoL</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.catalogueoflife.org/data/taxon/622CV">622CV</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Encyclopedia_of_Life" title="Encyclopedia of Life">EoL</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://eol.org/pages/1971">1971</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Global_Biodiversity_Information_Facility" title="Global Biodiversity Information Facility">GBIF</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.gbif.org/species/221">221</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/INaturalist" title="INaturalist">iNaturalist</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://inaturalist.org/taxa/47548">47548</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Interim_Register_of_Marine_and_Nonmarine_Genera" title="Interim Register of Marine and Nonmarine Genera">IRMNG</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.irmng.org/aphia.php?p=taxdetails&id=1079">1079</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Integrated_Taxonomic_Information_System" title="Integrated Taxonomic Information System">ITIS</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=157821">157821</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/National_Center_for_Biotechnology_Information" title="National Center for Biotechnology Information">NCBI</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=7625">7625</a></span></span></li> <li><span style="white-space:nowrap;">NZOR: <span class="uid"><a rel="nofollow" class="external text" href="https://www.nzor.org.nz/names/77ecce8f-b4ff-4738-b6ba-30a37aceac39">77ecce8f-b4ff-4738-b6ba-30a37aceac39</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Open_Tree_of_Life" title="Open Tree of Life">Open Tree of Life</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://tree.opentreeoflife.org/taxonomy/browse?id=669472">669472</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Paleobiology_Database" title="Paleobiology Database">Paleobiology Database</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=32733">32733</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/Plazi" title="Plazi">Plazi</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://treatment.plazi.org/id/CB1D34A5-4771-EBE7-5E44-DB0A2ACD89FA">CB1D34A5-4771-EBE7-5E44-DB0A2ACD89FA</a></span></span></li> <li><span style="white-space:nowrap;"><a href="/wiki/World_Register_of_Marine_Species" title="World Register of Marine Species">WoRMS</a>: <span class="uid"><a rel="nofollow" class="external text" href="https://www.marinespecies.org/aphia.php?p=taxdetails&id=123082">123082</a></span></span></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" 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