ADW: Cnidaria: INFORMATION

<!DOCTYPE html> <html xmlns:og="http://ogp.me/ns#" lang="en" xml:lang="en"> <head> <title>ADW: Cnidaria: INFORMATION</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="canonical" href="https://animaldiversity.org/accounts/Cnidaria/" /> <script type="text/javascript" src="//code.jquery.com/jquery-3.6.0.min.js"></script> <script type="text/javascript" src="//code.jquery.com/jquery-migrate-3.3.2.min.js"></script> <script type="text/javascript" src="/static/js/compat.js"></script> <link rel="shortcut icon" href="https://animaldiversity.org/favicon.ico" /> <link href="//fonts.googleapis.com/css?family=Gentium+Book+Basic:400,400italic,700,700italic" rel="stylesheet" type="text/css" /> <link href="//fonts.googleapis.com/css?family=PT+Sans:400,700,400italic,700italic" rel="stylesheet" type="text/css" /> <link rel="stylesheet" type="text/css" href="/static/bootstrap/css/bootstrap.css" /> <link rel="stylesheet" href="/static/css/pica.styles.css" /> <link rel="stylesheet" href="/static/css/pica.print.css" media="print" />  <link rel="stylesheet" type="text/css" href="/static/colorbox/colorbox.css" /> <meta property="og:url" content="https://animaldiversity.org/accounts/Cnidaria/" /> <meta content="Cnidaria (corals, sea anemones, jellyfish, and relatives)" property="og:title" /> <meta content="website" property="og:type" /> <meta content="Animal Diversity Web" property="og:site_name" /> <meta content="https://animaldiversity.org/collections/contributors/robert_bachand/Metridiidae/4_Frilled_anemone_Metridium_senile_LIS/medium.jpg" property="og:image" /> <meta name="twitter:card" content="summary" /> <meta name="twitter:site" content="@AnimalDiversity" /> <meta name="twitter:title" content="Cnidaria (corals, sea anemones, jellyfish, and relatives)" /> <meta name="twitter:description" content="Read about Cnidaria (corals, sea anemones, jellyfish, and relatives) on the Animal Diversity Web." /> <meta name="twitter:image:src" content="https://animaldiversity.org/collections/contributors/robert_bachand/Metridiidae/4_Frilled_anemone_Metridium_senile_LIS/medium.jpg" /> <meta name="twitter:image:height" content="480" /> <meta name="twitter:image:width" content="315" /> <meta name="twitter:url" content="https://animaldiversity.org/accounts/Cnidaria/" /> <script type="text/javascript" src="/static/js/Hyphenator.js"></script> <link rel="stylesheet" href="/static/social-likes/social-likes_birman.css" /> <style> .social-likes { margin: 0; } .social-likes__widget { margin: 0; } </style>   </head> <body> <div id="outerwrap"> <div id="header" aria-role="header"> <h1> <a id="homelink" href="/">Animal Diversity Web</a> </h1> <div class="umlinks"> <div class="relative"> <a href="https://lsa.umich.edu/ummz/" id="ummzlink">University of Michigan Museum of Zoology</a> <a href="https://www.umich.edu/" id="umlink">University of Michigan</a> </div> </div> </div> <div id="wrap" class="gradient"> <div class="container-fluid"> <div class="row-fluid"> <div class="span2 sidebar left"> <ul class="nav nav-tabs nav-stacked" id="sitemap"> <li> <a href="/">Home</a> </li> <li> <a href="/about/">About Us</a> </li> <li> <a href="/animal_names/">About Animal Names</a> </li> <li> <a href="/teach/">Educational Resources</a> </li> <li> <a href="/collections/">Special Collections</a> </li> <li> <a href="/glossary/">Glossary</a> </li> <li> <a href="/accounts/Animalia/">Browse Animalia</a> </li> </ul> <h2 class="offscreen">More Information</h2> <div class="well"> <h3>Additional Information</h3> <ul class="unstyled"> <li> <a href="http://eol.org/search/?q=Cnidaria&search=Go">Encyclopedia of Life</a> </li> </ul> </div> </div> <div class="span7_5 blahblahblah main" aria-role="main"> <h2 class="rank-phylum">Cnidaria<span class="vernacular-name">corals, sea anemones, jellyfish, and relatives</span></h2> <div class="social-likes" data-counters="no"> <div class="facebook" title="Share link on Facebook">Facebook</div> <div class="twitter" title="Share link on Twitter">Twitter</div> </div> <div class="snapshots" aria-hidden="true"> <ul> <li> <a href="/accounts/Cnidaria/pictures/collections/contributors/robert_bachand/Metridiidae/4_Frilled_anemone_Metridium_senile_LIS/"> <img alt=" " src="/collections/contributors/robert_bachand/Metridiidae/4_Frilled_anemone_Metridium_senile_LIS/button.jpg" border="0" /> </a> </li> <li> <a href="/accounts/Cnidaria/pictures/collections/contributors/robert_bachand/Cerianthidae/10_Cerianthid_anemone_Bonaire_DWI/"> <img alt=" " src="/collections/contributors/robert_bachand/Cerianthidae/10_Cerianthid_anemone_Bonaire_DWI/button.jpg" border="0" /> </a> </li> <li> <a href="/accounts/Cnidaria/pictures/collections/contributors/Grzimek_inverts/Scyphozoa/Stomolophus_meleagris/"> <img alt=" " src="/collections/contributors/Grzimek_inverts/Scyphozoa/Stomolophus_meleagris/button.jpg" border="0" /> </a> </li> <li> <a href="/accounts/Cnidaria/pictures/collections/contributors/Grzimek_inverts/Hydrozoa/Solmundella_bitentaculata_m/"> <img alt=" " src="/collections/contributors/Grzimek_inverts/Hydrozoa/Solmundella_bitentaculata_m/button.jpg" border="0" /> </a> </li> <li> <a href="/accounts/Cnidaria/pictures/collections/contributors/robert_bachand/Ulmaridae/25_Moon_jellyfish_Aurelia_aurita/"> <img alt=" " src="/collections/contributors/robert_bachand/Ulmaridae/25_Moon_jellyfish_Aurelia_aurita/button.jpg" border="0" /> </a> </li> </ul> </div> <div class="byline">By Phil Myers</div> <div class="inner-wrap"> <section class="hyphenate"> <p>The Phylum Cnidaria includes such diverse forms as jellyfish, hydra, sea anemones, and corals. Cnidarians are radially or biradially symmetric, a general type of symmetry believed primitive for eumetazoans. They have achieved the tissue level of organization, in which some similar cells are associated into groups or aggregations called tissues, but true organs do not occur. Cnidarian bodies have two or sometimes three layers. A gastrovascular cavity (coelenteron) has a single exterior opening that serves as both mouth and anus. Often tentacles surround the opening. Some cells are organized into two simple nerve nets, one epidermal and the other gastrodermal, that help coordinate muscular and sensory functions.</p> <p>Cnidarians have two basic body forms, medusa and polyp. <strong>Medusae</strong>, such as adult jellyfish, are free-swimming or floating. They usually have umbrella-shaped bodies and tetramerous (four-part) symmetry. The mouth is usually on the concave side, and the tentacles originate on the rim of the umbrella.</p> <p><strong>Polyps</strong>, in contrast, are usually sessile. They have tubular bodies; one end is attached to the substrate, and a mouth (usually surrounded by tentacles) is found at the other end. Polyps may occur alone or in groups of individuals; in the latter case, different individuals sometimes specialize for different functions, such as reproduction, feeding or defense.</p> <p>Reproduction in polyps is by asexual budding (polyps) or sexual formation of gametes (medusae, some polyps). Cnidarian individuals may be monoecious or dioecious. The result of sexual reproduction is a planula larva, which is ciliated and free-swimming.</p> <p>If collar cells and spicules are defining characteristics of the Phylum Porifera, then <strong>nematocysts</strong> define cnidarians. These tiny organelles, likened by Hickman to cocked guns, are both highly efficient devices for capturing prey and extremely effective deterrents to predators. Each contains a coiled, tubular thread, which may bear barbs and which is often poisoned. A nematocyst discharges when a prey species or predator comes into contact with it, driving its threads with barb and poison into the flesh of the victim by means of a rapid increase in hydrostatic pressure. Hundreds or thousands of nematocysts may line the tentacles or surface of the cnidarian. They are capable even of penetrating human skin, sometimes producing a painful wound or in extreme cases, death.</p> <p><strong>Sources</strong>:</p> <p>Hickman, C.P. and L. S. Roberts. 1994. <em>Animal Diversity</em>. Wm. C. Brown, Dubuque, IA.</p> <p>Brusca, R. C., and G. J. Brusca. <em>Invertebrates</em>. 1990. Sinauer Associates, Sunderland, MA.</p> </section> <section class="hyphenate"> <h3 id="contributors">Contributors</h3> <p>Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor. </p> </section> </div> </div> <div class="span2_5 right sidebar"> <div class="well" id="pocket-guide-link"> <a href="https://itunes.apple.com/us/app/adw-pocket-guide/id916179421?mt=8" target="_blank"><i class="icon-download icon-white" style="vertical-align: bottom"></i> ADW Pocket Guides on the iOS App Store! </a> <p>The Animal Diversity Web team is excited to announce ADW Pocket Guides!</p> <p> <a href="/news/5009059054038197651/">Read more...</a> </p> </div> <h2 class="offscreen">Search</h2> <div id="site-search"> <form action="/search" method="GET"> <label for="q" class="offscreen">Enter search text</label> <input value="" id="q" name="q" class="span12" size="15" type="text" placeholder="Search ADW" /> <button class="btn"> <i class="icon-zoom-in"></i> <span class="offscreen">Search</span> </button> <p style="max-height: 35px"> <label for="feature-list" class="offscreen">Search in feature</label> <select size="1" name="feature" class="feature-list input-medium" id="feature-list"> <option value="INFORMATION">Taxon Information</option> <option value="COLLECTIONS">Contributor Galleries</option> <option value="TOPICS">Topics</option> <option value="CLASSIFICATION">Classification</option> </select> </p> </form> <ul class="unstyled"> <li> <a href="https://animaldiversity.ummz.umich.edu/quaardvark/">Explore Data @ Quaardvark</a> </li> <li> <a href="/search_guide/">Search Guide</a> </li> </ul> </div> <h2 class="offscreen">Navigation Links</h2> <dl class="tabbed features"> <dd class="feature-information active"> <a name="feature-information" href="/accounts/Cnidaria/" class="active" id="feature-information"> Information </a> </dd> <dd class="feature-pictures"> <a name="feature-pictures" href="/accounts/Cnidaria/pictures/" id="feature-pictures"> Pictures </a> </dd> <dd class="feature-specimens"> <a name="feature-specimens" href="/accounts/Cnidaria/specimens/" id="feature-specimens"> Specimens </a> </dd> <dd class="feature-classification"> <a name="feature-classification" href="/accounts/Cnidaria/classification/#Cnidaria" id="feature-classification"> Classification </a> </dd> </dl> <div class="classification well"> <h3>Classification</h3> <ul class="unstyled"> <li> <span class="rank">Kingdom</span> <a href="/accounts/Animalia/" class="taxon-name rank-kingdom">Animalia</a> <span class="vernacular-name">animals</span> <div class="features"> <a href="/accounts/Animalia/" class="feature feature-information" rel="tooltip" data-original-title="Animalia: information (1)" data-delay="250" data-total="4749">Animalia: information (1)</a> <a href="/accounts/Animalia/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Animalia: pictures (22861)" data-delay="250">Animalia: pictures (22861)</a> <a href="/accounts/Animalia/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Animalia: specimens (7109)" data-delay="250">Animalia: specimens (7109)</a> <a href="/accounts/Animalia/sounds/" class="feature feature-sounds" rel="tooltip" data-original-title="Animalia: sounds (722)" data-delay="250">Animalia: sounds (722)</a> <a href="/accounts/Animalia/maps/" class="feature feature-maps" rel="tooltip" data-original-title="Animalia: maps (42)" data-delay="250">Animalia: maps (42)</a> </div> </li> <li class="active"> <span class="rank">Phylum</span> <a href="/accounts/Cnidaria/" class="taxon-name rank-phylum">Cnidaria</a> <span class="vernacular-name">corals, sea anemones, jellyfish, and relatives</span> <div class="features"> <a href="/accounts/Cnidaria/" class="feature feature-information" rel="tooltip" data-original-title="Cnidaria: information (1)" data-delay="250" data-total="53">Cnidaria: information (1)</a> <a href="/accounts/Cnidaria/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Cnidaria: pictures (168)" data-delay="250">Cnidaria: pictures (168)</a> <a href="/accounts/Cnidaria/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Cnidaria: specimens (7)" data-delay="250">Cnidaria: specimens (7)</a> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> </ul> </div> <div class="related navlist well"> <h3>Related Taxa</h3> <ul class="descendants classification unstyled"> <li> <span class="rank">Class</span> <a href="/accounts/Anthozoa/" class="taxon-name rank-class">Anthozoa</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Anthozoa/" class="feature feature-information" rel="tooltip" data-original-title="Anthozoa: information (1)" data-delay="250" data-total="22">Anthozoa: information (1)</a> <a href="/accounts/Anthozoa/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Anthozoa: pictures (67)" data-delay="250">Anthozoa: pictures (67)</a> <span class="feature-off feature-specimens"></span> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> <li> <span class="rank">Class</span> <a href="/accounts/Cubozoa/" class="taxon-name rank-class">Cubozoa</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Cubozoa/" class="feature feature-information" rel="tooltip" data-original-title="Cubozoa: information (1)" data-delay="250" data-total="5">Cubozoa: information (1)</a> <a href="/accounts/Cubozoa/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Cubozoa: pictures (3)" data-delay="250">Cubozoa: pictures (3)</a> <span class="feature-off feature-specimens"></span> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> <li> <span class="rank">Species</span> <a href="/accounts/Haliclystus_auricula/" class="taxon-name rank-species">Haliclystus auricula</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Haliclystus_auricula/" class="feature feature-information" rel="tooltip" data-original-title="Haliclystus auricula: information (1)" data-delay="250" data-total="1">Haliclystus auricula: information (1)</a> <a href="/accounts/Haliclystus_auricula/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Haliclystus auricula: pictures (1)" data-delay="250">Haliclystus auricula: pictures (1)</a> <span class="feature-off feature-specimens"></span> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> <li> <span class="rank">Class</span> <a href="/accounts/Hydrozoa/" class="taxon-name rank-class">Hydrozoa</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Hydrozoa/" class="feature feature-information" rel="tooltip" data-original-title="Hydrozoa: information (1)" data-delay="250" data-total="11">Hydrozoa: information (1)</a> <a href="/accounts/Hydrozoa/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Hydrozoa: pictures (60)" data-delay="250">Hydrozoa: pictures (60)</a> <a href="/accounts/Hydrozoa/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Hydrozoa: specimens (4)" data-delay="250">Hydrozoa: specimens (4)</a> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> <li> <span class="rank">Class</span> <a href="/accounts/Scyphozoa/" class="taxon-name rank-class">Scyphozoa</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Scyphozoa/" class="feature feature-information" rel="tooltip" data-original-title="Scyphozoa: information (1)" data-delay="250" data-total="13">Scyphozoa: information (1)</a> <a href="/accounts/Scyphozoa/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Scyphozoa: pictures (36)" data-delay="250">Scyphozoa: pictures (36)</a> <a href="/accounts/Scyphozoa/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Scyphozoa: specimens (3)" data-delay="250">Scyphozoa: specimens (3)</a> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> </ul> </div> </div> </div> </div> </div> <div id="footer" aria-role="contentinfo"> <div class="inner-footer"> <div class="page-citation"> <p class="content">To cite this page: Myers, P. 2001. "Cnidaria" (On-line), Animal Diversity Web. Accessed November 25, 2024 at https://animaldiversity.org/accounts/Cnidaria/</p> </div> <div class="disclaimer"> <p class="content"><strong>Disclaimer:</strong> The Animal Diversity Web is an educational resource <strong>written largely by and for college students</strong>. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control. </p> </div> <div class="footer-links"> <ul class="unstyled"> <li><a href="https://www.umich.edu/">U-M Gateway</a> | <a href="https://lsa.umich.edu/ummz/">U-M Museum of Zoology</a></li> <li> <a href="https://lsa.umich.edu/eeb/">U-M Ecology and Evolutionary Biology</a> </li> <li> 漏 2020 Regents of the University of Michigan </li> <li><a href="/feedback/error_form/">Report Error</a> / <a href="/feedback/comment_form/">Comment</a></li> </ul> </div> <div class="thanks-links"> <p>This material is based upon work supported by the <a href="https://nsf.gov">National Science Foundation</a> Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services. </p> <p> The ADW Team gratefully acknowledges their support. </p> </div> </div> </div> <script></script> </div> <script src="/static/js/jquery.colorbox.js"></script> <script src="/static/js/pica.information.js"></script> <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); </script> <script type="text/javascript"> try { var pageTracker = _gat._getTracker("UA-7143967-1"); pageTracker._setCustomVar(1,"author",":Myers,Phil:",3); pageTracker._setCustomVar(3,"organization",":University of Michigan-Ann Arbor:",3); pageTracker._trackPageview(); } catch(err) {} </script> <script type="text/javascript"> (function(c,l,a,r,i,t,y){ c[a]=c[a]||function(){(c[a].q=c[a].q||[]).push(arguments)}; t=l.createElement(r);t.async=1;t.src="https://www.clarity.ms/tag/"+i; y=l.getElementsByTagName(r)[0];y.parentNode.insertBefore(t,y); })(window, document, "clarity", "script", "6f4vquqfce"); </script> <script async="async" src="https://www.googletagmanager.com/gtag/js?id=G-0ZHSR6DBVK"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-0ZHSR6DBVK'); </script> <script type="text/javascript" src="/static/bootstrap/js/bootstrap.js"></script> <script type="text/javascript" src="/static/social-likes/social-likes.min.js"></script> <script type="text/javascript" src="/static/js/links.js"></script> </body> </html>

CINXE.COM

ADW: Cnidaria: INFORMATION