Amphibian | Characteristics, Life Cycle, & Facts

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top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/animal/amphibian">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref40612"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/animal/amphibian/General-features">General features</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref40613"><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40613">Size range and diversity of structure</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40614"><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40614">Distribution and abundance</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40615"><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40615">Economic importance</a></li></ul></div></li><li data-target="#ref40616"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40616">Natural history</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref40618"><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40618">Reproduction</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref40619"><a class="w-100 link-gray-900" href="/animal/amphibian/General-features#ref40619">Embryonic stage</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref40620"><a class="w-100 link-gray-900" href="/animal/amphibian/Larval-stage">Larval stage</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref40621"><a class="w-100 link-gray-900" href="/animal/amphibian/Larval-stage#ref40621">Metamorphosis</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref40622"><a class="w-100 link-gray-900" href="/animal/amphibian/Larval-stage#ref40622">Heterochrony </a></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40617"><a class="w-100 link-gray-900" href="/animal/amphibian/Larval-stage#ref40617">Life cycle</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40624"><a class="w-100 link-gray-900" href="/animal/amphibian/Larval-stage#ref40624">Food and feeding</a></li></ul></div></li><li data-target="#ref40625"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function">Form and function</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref276437"><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function#ref276437">Common features</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40627"><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function#ref40627">Structural differences</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref276438"><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function#ref276438">Salamanders</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref276439"><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function#ref276439">Caecilians</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref276440"><a class="w-100 link-gray-900" href="/animal/amphibian/Form-and-function#ref276440">Anurans</a></li></ul></li></ul></div></li><li data-target="#ref276441"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/animal/amphibian/Evolution-and-classification">Evolution and classification</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref40630"><a class="w-100 link-gray-900" href="/animal/amphibian/Annotated-classification">Annotated classification</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref40631"><a class="w-100 link-gray-900" href="/animal/amphibian/Annotated-classification#ref40631">Critical appraisal</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/animal/amphibian/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/amphibian">Quick Facts & Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/animal/amphibian/images-videos">Images & Videos</a> <div class="slider js-slider position-relative d-inline-flex 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</div> </a> <a href="https://cdn.britannica.com/45/181945-050-EC215D7B/leaf-frog-Amazon-liana-rainforest-Ecuadorean-frogs.jpg" data-href="/media/1/21445/196986" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/45/181945-004-5638334C/leaf-frog-Amazon-liana-rainforest-Ecuadorean-frogs.jpg" alt="Amazon leaf frog" height="50" /> </a> <a href="https://cdn.britannica.com/85/50685-050-ACFB64D3/Life-cycle-European-frog.jpg" data-href="/media/1/21445/43164" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/85/50685-004-C276FCBB/Life-cycle-European-frog.jpg" alt="life cycle of the European common frog" height="50" /> </a> <a href="https://cdn.britannica.com/74/50674-050-FADB5788/types-salamander-larvae.jpg" data-href="/media/1/21445/201454" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/74/50674-004-9D6EA15D/types-salamander-larvae.jpg" 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Floats on back. 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Let us know if you have suggestions to improve this article (requires login). </div> <div class="type-menu"> <label for="feedback-type" class="label mb-10">Feedback Type</label> <select id="feedback-type" class="form-select mb-30" name="feedbackTypeId" required> <option value="" selected="selected">Select a type (Required)</option> <option value="1">Factual Correction</option> <option value="2">Spelling/Grammar Correction</option> <option value="3">Link Correction</option> <option value="4">Additional Information</option> <option value="5">Other</option> </select> </div> <label for="feedback" class="label mb-10">Your Feedback</label> <textarea id="feedback" class="form-control mb-30" name="feedback" maxlength="3000" rows="7" required></textarea> <button class="btn btn-blue" type="submit">Submit Feedback</button> </form> <div class="success-messaging d-none mt-30"> <div class="title">Thank you for your feedback</div> <p>Our editors will review what you’ve submitted and determine whether to revise the article.</p> </div> </div> </div> <div class="md-websites-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom font-weight-bold"> External Websites </div> <div class="pb-20"> <ul class="list-unstyled mt-20 lh-lg"> <li><a class="external" href="https://www.nature.com/articles/s41467-022-34474-4" target="_blank" rel="noopener ">Nature - The evolution of reproductive modes and life cycles in amphibians</a></li> <li><a class="external" href="https://www.thecanadianencyclopedia.ca/en/article/amphibian" target="_blank" rel="noopener ">The Canadian Encyclopedia - Amphibian</a></li> <li><a class="external" href="https://a-z-animals.com/animals/amphibians/" target="_blank" rel="noopener ">AZ Animals - Amphibians: Different Types, Definition, Photos, and More</a></li> <li><a class="external" href="https://ucmp.berkeley.edu/vertebrates/tetrapods/amphibintro.html" target="_blank" rel="noopener ">University of California Museum of Paleontology - Introduction to the Amphibia</a></li> <li><a class="external" href="https://ijcrt.org/papers/IJCRT1133540.pdf" target="_blank" rel="noopener ">International Journal of Creative Research Thoughts - Role of Amphibians in Ecosystem Balance</a></li> <li><a class="external" href="https://animalcorner.org/amphibian/" target="_blank" rel="noopener ">Animal Corner - What is an Amphibian?</a></li> <li><a class="external" href="https://www.burkemuseum.org/collections-and-research/biology/herpetology/all-about-amphibians/all-about-amphibians" target="_blank" rel="noopener ">Burke Museum - All About Amphibians</a></li> <li><a class="external" href="https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/General_Biology_1e_(OpenStax)/5%3A_Biological_Diversity/29%3A_Vertebrates/29.3%3A_Amphibians" target="_blank" rel="noopener ">Biology LibreTexts - Amphibian</a></li> </ul> </div> <div class="md-websites-ebk-title">Britannica Websites</div> <div class="md-websites-ebk-subtitle">Articles from Britannica Encyclopedias for elementary and high school students.</div> <ul class="list-unstyled bps-topic-web-sites lh-lg"> <li><a class="external" href="https://kids.britannica.com/kids/article/amphibian/352745" target="_blank" rel="noopener">amphibian - Children's Encyclopedia (Ages 8-11)</a></li> <li><a class="external" href="https://kids.britannica.com/students/article/amphibian/272842" target="_blank" rel="noopener">amphibian - Student Encyclopedia (Ages 11 and up)</a></li> </ul> </div> </div> </div> </div> <div class="toc-header-marker"></div> <button class="ai-ask-button btn border-2 js-header-ai-ask-button d-none btn-sm btn-outline-red-400 border-red-400 mr-0 mr-lg-10 ml-5 ml-sm-10 ml-lg-0 p-10"> Ask the Chatbot a Question </button> <div class="caption alternate-titles">Also known as: Amphibia</div> <div class="md-byline module-spacing "> <div class="font-serif font-12"> <span class="written-by text-gray-700"> Written by </span> <div class="editor-popover popover p-0"> <a class="d-block p-20 gtm-byline font-12 byline-contributor" href="/contributor/William-E-Duellman/792" > <div class="editor-title font-16 font-weight-bold">William E. Duellman</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Curator, Division of Herpetology, Museum of Natural History; Professor of Systematics and Ecology, University of Kansas, Lawrence. Author of <em>The Hylid Frogs of Middle America</em><em>.</em></div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> William E. Duellman</span>, <div class="editor-popover popover p-0"> <a class="d-block p-20 gtm-byline font-12 byline-contributor" href="/contributor/George-R-Zug/3321" > <div class="editor-title font-16 font-weight-bold">George R. Zug</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Curator Emeritus, Division of Amphibians and Reptiles, National Museum of Natural History, Smithsonian Institution, Washington, D.C.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> George R. Zug</span><span class="text-gray-700 mx-5">•</span><a class="see-all border-gray-700 gtm-byline" rel="nofollow" href="https://www.britannica.com/animal/amphibian/additional-info#contributors">All</a> </div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2024-10-25T00:00:00CDT" >Oct 25, 2024</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/animal/amphibian/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/animal/caecilian-amphibian" topicid="29797">Gymnophiona</a></dd> <dd><a href="/animal/frog" topicid="220611">frog</a></dd> <dd><a href="/animal/toad" topicid="597631">toad</a></dd> <dd><a href="/animal/salamander" topicid="518911">salamander</a></dd> <dd><a href="/animal/lepospondyl" topicid="336860">lepospondyl</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/amphibian"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><div class="assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100" data-type="other"><div class="slider-container js-slider-container overflow-hidden d-flex"><div class="rw-track d-flex align-items-center"><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="38443" data-asm-type="image"><div class="md-assembly-wrapper card-media " data-type="image"><a href="https://cdn.britannica.com/72/45872-004-8FBD2FE1/Green-frog.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/21445/38443"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/72/45872-004-8FBD2FE1/Green-frog.jpg?w=300"><img src="https://cdn.britannica.com/72/45872-004-8FBD2FE1/Green-frog.jpg?w=300" alt="Green frog (Rana clamitans melanota)." data-width="550" data-height="344" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/72/45872-004-8FBD2FE1/Green-frog.jpg" data-href="/media/1/21445/38443">Green frog (<em>Rana clamitans melanota</em>).</a><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div></div><button disabled="true" class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_left"></span></button><button disabled="true" class="next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_right"></span></button></div><p class="topic-paragraph"><strong><span id="ref467472"></span>amphibian</strong>, (class Amphibia), any member of the group of <a href="https://www.britannica.com/animal/vertebrate" class="md-crosslink " data-show-preview="true">vertebrate</a> animals <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="characterized" href="https://www.britannica.com/dictionary/characterized" data-type="EB">characterized</a> by their ability to exploit both aquatic and terrestrial <a href="https://www.britannica.com/science/habitat-biology" class="md-crosslink " data-show-preview="true">habitats</a>. The name <em>amphibian</em>, derived from the Greek <em>amphibios</em> meaning “living a double life,” reflects this dual life strategy—though some species are permanent land dwellers, while other species have a completely aquatic mode of existence.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Approximately 8,100 species of living amphibians are known. First appearing about 340 million years ago during the <a href="https://www.britannica.com/science/Mississippian-Subperiod" class="md-crosslink " data-show-preview="true">Middle Mississippian Epoch</a>, they were one of the earliest groups to diverge from ancestral fish-tetrapod stock during the <a href="https://www.britannica.com/science/evolution-scientific-theory" class="md-crosslink autoxref " data-show-preview="true">evolution</a> of animals from strictly aquatic forms to terrestrial types. Today amphibians are represented by <span id="ref992550"></span><a href="https://www.britannica.com/animal/frog" class="md-crosslink " data-show-preview="true">frogs</a> and <span id="ref992551"></span><a href="https://www.britannica.com/animal/toad" class="md-crosslink " data-show-preview="true">toads</a> (order <span id="ref467528"></span><a href="https://www.britannica.com/animal/Anura" class="md-crosslink " data-show-preview="true">Anura</a>), <a href="https://www.britannica.com/animal/newt" class="md-crosslink " data-show-preview="true">newts</a> and <a href="https://www.britannica.com/animal/salamander" class="md-crosslink " data-show-preview="true">salamanders</a> (order <a href="https://www.britannica.com/animal/Caudata" class="md-crosslink " data-show-preview="true">Caudata</a>), and <span id="ref1044316"></span>caecilians (order <span id="ref467542"></span><a href="https://www.britannica.com/animal/caecilian-amphibian" class="md-crosslink " data-show-preview="true">Gymnophiona</a>). These three orders of living <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="amphibians" href="https://www.britannica.com/dictionary/amphibians" data-type="EB">amphibians</a> are thought to derive from a single radiation of ancient amphibians, and although strikingly different in body form, they are probably the closest relatives to one another. As a group, the three orders make up subclass <span id="ref467525"></span><a href="https://www.britannica.com/animal/lissamphibian" class="md-crosslink ">Lissamphibia</a>. Neither the lissamphibians nor any of the extinct groups of amphibians were the ancestors of the group of <a href="https://www.britannica.com/animal/tetrapod-animal" class="md-crosslink " data-show-preview="true">tetrapods</a> that gave rise to <a href="https://www.britannica.com/animal/reptile" class="md-crosslink " data-show-preview="true">reptiles</a>. Though some aspects of the biology and anatomy of the various amphibian groups might demonstrate features possessed by reptilian ancestors, amphibians are not the intermediate step in the evolution of reptiles from <a href="https://www.britannica.com/animal/fish" class="md-crosslink " data-show-preview="true">fishes</a>.</p><span class="marker MOD2 mod-inline"></span><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Modern amphibians are united by several unique traits. They typically have a moist skin and rely heavily on cutaneous (skin-surface) <a href="https://www.britannica.com/science/respiratory-system" class="md-crosslink " data-show-preview="true">respiration</a>. They possess a double-channeled hearing system, green <a href="https://www.britannica.com/science/rod-retinal-cell" class="md-crosslink " data-show-preview="true">rods</a> in their retinas to discriminate hues, and pedicellate (two-part) teeth. Some of these traits may have also existed in extinct groups.</p><span class="marker MOD3 mod-inline"></span><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Members of the three <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="extant" href="https://www.merriam-webster.com/dictionary/extant" data-type="MW">extant</a> orders differ markedly in their structural appearance. Frogs and toads are tailless and somewhat squat with long, powerful hind limbs modified for leaping. In contrast, caecilians are limbless, wormlike, and highly adapted for a burrowing existence. <span id="ref992556"></span><a href="https://www.britannica.com/animal/salamander" class="md-crosslink " data-show-preview="true">Salamanders</a> and <span id="ref467476"></span><a href="https://www.britannica.com/animal/newt" class="md-crosslink " data-show-preview="true">newts</a> have tails and two pairs of limbs of roughly the same size; however, they are somewhat less specialized in body form than the other two orders.</p><div class="one-good-fact-module"> </div><span class="marker MOD4 mod-inline"></span><span class="marker PREMOD5 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="110052" data-asm-type="video"><div class="md-assembly-wrapper card-media " data-type="video" video-id="81640"><a data-id="81640" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/characteristics-amphibians/-110052"><img src="https://cdn.britannica.com/40/81640-138-857CF9D2/characteristics-amphibians.jpg?w=800&h=450&c=crop" alt="Follow an amphibian's life cycle from an underwater egg to a land-roving organism" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/3ncHI7EK.m3u8" } ], "image": "https://cdn.britannica.com/40/81640-138-857CF9D2/characteristics-amphibians.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/yx5Nn3ez", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/rIbAKF5j.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="81640">Follow an amphibian's life cycle from an underwater egg to a land-roving organism</span><span>General characteristics of amphibians.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/animal/amphibian/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph">Many amphibians are obligate breeders in standing water. <a href="https://www.britannica.com/science/egg-biology" class="md-crosslink " data-show-preview="true">Eggs</a> are laid in water, and the developing <a href="https://www.britannica.com/science/larva" class="md-crosslink autoxref " data-show-preview="true">larvae</a> are essentially free-living <a href="https://www.britannica.com/science/embryo-human-and-animal" class="md-crosslink " data-show-preview="true">embryos</a>; they must find their own food, escape predators, and perform other life functions while they continue to develop. As the larvae complete their embryonic development, they adopt an adult body plan that allows them to leave aquatic habitats for <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="terrestrial" href="https://www.britannica.com/dictionary/terrestrial" data-type="EB">terrestrial</a> ones. Even though this <a href="https://www.britannica.com/science/metamorphosis" class="md-crosslink " data-show-preview="true">metamorphosis</a> from aquatic to terrestrial life occurs in members of all three amphibian groups, there are many variants, and some taxa bear their young alive. Indeed, the roughly 8,100 living species of amphibians display more evolutionary experiments in reproductive mode than any other vertebrate group. Some taxa have aquatic eggs and larvae, whereas others embed their eggs in the skin on the back of the female; these eggs hatch as <a href="https://www.britannica.com/science/tadpole" class="md-crosslink " data-show-preview="true">tadpoles</a> or miniature frogs. In other groups, the young develop within the oviduct, with the embryos feeding on the wall of the oviduct. In some species, eggs develop within the female’s stomach.</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/deadliest-animals-quiz" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/54/92754-131-661B61DB/lion-Panthera-leo.jpg" alt="Lion (panthera leo)" class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Deadliest Animals Quiz</div> </div> </a><span class="marker MOD5 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":6,"pageId":21445,"pageLength":545,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.14"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.14' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"D","adLeg":"D","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Amphibian | Characteristics, Life Cycle, & Facts | Britannica