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BABY I'M PREYING ON YOU TONIGHT 🗣️🗣️🗣️🔥🔥🔥
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{{short description|2014 single by Maroon 5}}
{{Short description|Kingdom of living things}}
{{Other uses}}
{{about|the Maroon 5 song|the song by [[Nickelback]]|Animals (Nickelback song)|other uses|Animal (disambiguation)}}
{{redirect|Animalia|other uses}}
{{Use mdy dates|date=March 2022}}
{{pp-semi-indef}}
{{Infobox song
{{pp-move}}
| name = Animals
{{good article}}
| cover = Maroon 5 - Animals Single Cover.png
{{Use British English|date=April 2017}}
| alt =
{{Use dmy dates|date=August 2024}}
| border = yes
{{automatic taxobox
| type = single
|name = Animals
| artist = [[Maroon 5]]
|display_parents = 6
| album = [[V (Maroon 5 album)|V]]
|taxon = Animalia
| released = {{start date|2014|8|25}}
|authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| recorded = <!--do NOT add unsourced recorded years-->
|fossil_range = [[Cryogenian]] – present, {{Long fossil range |665|0}}<!--please do not attempt to change this without providing citations to reliable evidence in the body of this article; the infobox is to reflect what the article says, not to introduce anything "new"-->
| studio =
|image = <imagemap>
* [[MXM Studios|MXM]], Stockholm
File:Animal diversity b.png |300px
* [[Conway Recording Studios|Conway]], Los Angeles

| genre = *[[Pop rock]]<ref>{{citeweb|title=Animals by Marron 5|url=https://rateyourmusic.com/release/single/maroon-5/animals}}</ref>
rect 0 0 118 86 [[Echinoderm]]
*[[electro-pop]]<ref>{{citeweb|title=Animals by Maroon 5|url=https://rateyourmusic.com/release/single/maroon-5/animals}}</ref>
rect 0 86 118 172 [[Cnidaria]]
*[[dance-rock]]
rect 0 172 118 258 [[Tardigrade]]
| length = 3:51
rect 0 258 118 344 [[Crustacean]]
| label =
rect 0 344 118 430 [[Arachnid]]
* [[222 Records|222]]

* [[Interscope Records|Interscope]]
rect 118 0 236 86 [[Sponge]]
| writer =
rect 118 86 236 172 [[Insect]]
* [[Adam Levine]]
rect 118 172 236 258 [[Bryozoa]]
* [[Shellback (record producer)|Shellback]]
rect 118 258 236 344 [[Acanthocephala]]
* [[Benny Blanco|Benjamin Levin]]
rect 118 344 236 430 [[Flatworm]]
| producer = Shellback

| prev_title = [[Maps (Maroon 5 song)|Maps]]
rect 236 0 354 86 [[Mollusca]]
| prev_year = 2014
rect 236 86 354 172 [[Annelid]]
| next_title = [[Sugar (Maroon 5 song)|Sugar]]
rect 236 172 354 258 [[Vertebrate]]
| next_year = 2015
rect 236 258 354 344 [[Tunicate]]
| misc = {{External music video|{{Plain list|
rect 236 344 354 430 [[Phoronida]]
*{{YouTube|qpgTC9MDx1o|"Animals"}}

*{{YouTube|7BJ3ZXpserc|"Animals" (Lyric Video)}}}}
</imagemap>
|header=Music videos}}
|image_upright = 1.4
|subdivision_ranks = Subdivisions
|subdivision = *[[Bilateria]] (~30 phyla)
* [[Cnidaria]]
* [[Ctenophora]]
* [[Placozoa]]
* [[Porifera]]
|synonyms = * Metazoa {{au|Haeckel 1874}}<ref name="Phylonyms Metazoa">{{cite book |chapter=Metazoa E. Haeckel 1874 [J. R. Garey and K. M. Halanych], converted clade name |title=Phylonyms: A Companion to the PhyloCode |edition=1st |date=2020 |publisher=[[CRC Press]] |doi=10.1201/9780429446276 |pages=1352 |isbn=9780429446276 |s2cid=242704712 |editor-first1=Kevin |editor-last1=de Queiroz |editor-first2=Philip |editor-last2=Cantino |editor-first3=Jacques|editor-last3=Gauthier}}</ref>
* Choanoblastaea {{au|Nielsen 2008}}<ref name="Choanoblastaea">{{cite journal |title=Six major steps in animal evolution: are we derived sponge larvae? |journal=Evolution & Development |volume=10 |issue=2 |date=2008 |pages=241–257 |first1=Claus |last1=Nielsen |doi=10.1111/j.1525-142X.2008.00231.x |pmid=18315817 |s2cid=8531859 |issn = 1520-541X }}</ref>
* Gastrobionta {{au|Rothm. 1948}}<ref name="Rothmaler">{{cite journal |first1=Werner |last1=Rothmaler |date=1951 |title=Die Abteilungen und Klassen der Pflanzen |journal=Feddes Repertorium, Journal of Botanical Taxonomy and Geobotany |doi=10.1002/fedr.19510540208 |volume=54 |issue=2–3 |pages=256–266}}</ref>
* Zooaea {{au|Barkley 1939}}<ref name="Rothmaler"/>
* Euanimalia {{au|Barkley 1939}}<ref name="Rothmaler"/>
}}
}}
'''Animals''' are [[multicellular]], [[eukaryotic]] [[organism]]s in the [[Kingdom (biology)|biological kingdom]] '''Animalia''' ({{IPAc-en|ˌ|æ|n|ɪ|ˈ|m|eɪ|l|i|ə}}<ref>{{Cite Merriam-Webster|animalia|accessdate=12 May 2024}}</ref>). With few exceptions, animals [[heterotroph|consume organic material]], [[Cellular respiration#Aerobic respiration|breathe oxygen]], have [[myocyte]]s and are [[motility|able to move]], can [[sexual reproduction|reproduce sexually]], and grow from a hollow sphere of cells, the [[blastula]], during [[embryonic development]]. Animals form a [[clade]], meaning that they arose from a single common ancestor.


Over 1.5 million<!--<ref name="Zhang2013"/>--> [[extant taxon|living]] animal [[species]] have been [[species description|described]], of which around 1.05 million are [[insect]]s, over 85,000 are [[mollusc]]s, and around 65,000 are [[vertebrate]]s. It has been estimated there are as many as 7.77&nbsp;million animal species on Earth. Animal body lengths range from {{cvt|8.5|μm|in}} to {{cvt|33.6|m|ft}}. They have complex [[ecologies]] and [[biological interaction|interaction]]s with each other and their environments, forming intricate [[food web]]s. The scientific study of animals is known as [[zoology]], and the study of animal behaviors is known as [[ethology]].
"'''Animals'''" is a song by the American [[pop rock]] band [[Maroon 5]]. It was released on August 25, 2014, as the second single from the band's fifth studio album ''[[V (Maroon 5 album)|V]]'' (2014). The song was written by [[Adam Levine]], [[Benny Blanco]] and its producer [[Shellback (record producer)|Shellback]].


Most living animal species belong to the infrakingdom [[Bilateria]], a highly proliferative [[clade]] whose members have a [[symmetry in biology#Bilateral symmetry|bilaterally symmetric]] [[body plan]]. The vast majority belong to two large [[superphyla]]: the [[protostome]]s, which includes organisms such as the [[arthropod]]s, [[mollusc]]s, [[flatworm]]s, [[annelid]]s and [[nematode]]s; and the [[deuterostome]]s, which include the [[echinoderm]]s, [[hemichordate]]s and [[chordate]]s, the latter of which contains the vertebrates. The simple [[Xenacoelomorpha]] have an uncertain position within Bilateria.
The song peaked at number three on the US [[Billboard Hot 100|''Billboard'' Hot 100]] giving Maroon 5 their tenth top 10 single in the U.S.


Animals first appear in the fossil record in the late [[Cryogenian]] period and diversified in the subsequent [[Ediacaran]]. Earlier evidence of animals is still controversial; the [[sponge]]-like organism ''[[Otavia]]'' has been dated back to the [[Tonian]] period at the start of the [[Neoproterozoic]], but its identity as an animal is heavily contested.<ref>{{cite journal |last1=Antcliffe |first1=Jonathan B. |last2=Callow |first2=Richard H. T. |last3=Brasier |first3=Martin D. |title=Giving the early fossil record of sponges a squeeze |journal=Biological Reviews |date=November 2014 |volume=89 |issue=4 |pages=972–1004 |doi=10.1111/brv.12090 |pmid=24779547 |s2cid=22630754 }}</ref> Nearly all modern animal phyla became clearly established in the fossil record as [[Marine life|marine species]] during the [[Cambrian explosion]], which began around 539&nbsp;[[million years ago]] (Mya), and most [[class (biology)|class]]es during the [[Ordovician radiation]] 485.4&nbsp;Mya. 6,331 groups of [[gene]]s common to all living animals have been identified; these may have arisen from a single [[#Phylogeny|common ancestor]] that lived about 650&nbsp;Mya during the [[Cryogenian]] period.
==Promotion==
To promote the song, [[Kia Motors]] debuted an advertisement of 2015 [[Kia Soul EV]] model on August 21, 2014.<ref>{{cite web|url=https://www.kiamedia.com/us/en/media/pressreleases/9206/kia-motors-iconic-hamsters-turn-science-lab-into-hotbed-of-innovation-in-campaign-for-the-brands-first-electric-vehicle-the-soul-ev|title=Kia Motors' Iconic Hamsters Turn Science Lab Into Hotbed Of Innovation In Campaign For The Brand's First Electric Vehicle – The Soul EV|work=Kia Media|date=August 21, 2014|access-date=July 23, 2019}}</ref> For a limited time after the commercial premiered, "Animals" was available for free download on the Kia website only.<ref>{{cite web|url=http://abcnewsradioonline.com/music-news/2014/8/22/new-maroon-5-song-animals-featured-in-new-kia-commercial-dow.html|title=New Maroon 5 Song "Animals" Featured in New KIA Commercial, Download It for Free|work=ABC News Radio Online|date=August 22, 2014|access-date=September 4, 2014|archive-date=September 4, 2014|archive-url=https://web.archive.org/web/20140904143728/http://abcnewsradioonline.com/music-news/2014/8/22/new-maroon-5-song-animals-featured-in-new-kia-commercial-dow.html|url-status=dead}}</ref> Later, Maroon 5 released the song's lyric video on August 22, 2014, from their YouTube channel.<ref>{{cite web|url=https://www.popdust.com/maroon-5-rolls-in-the-hay-with-bunnies-snakes-in-animals-lyric-video-1890026200.html|title=Maroon 5 Rolls In The Hay With Bunnies & Snakes In 'Animals' Lyric Video!|work=Popdust|last=Scott|first=Jason|date=August 22, 2014|access-date=August 24, 2019|archive-date=August 24, 2019|archive-url=https://web.archive.org/web/20190824102355/https://www.popdust.com/maroon-5-rolls-in-the-hay-with-bunnies-snakes-in-animals-lyric-video-1890026200.html|url-status=dead}}</ref> The commercial also appeared at the [[2014 MTV Video Music Awards]] on August 24,<ref>{{cite web|url=https://www.ispot.tv/blog/kia-resurrects-its-hamsters-for-the-mtv-vmas-and/|title=Kia Resurrects Its Hamsters for the MTV VMAs and Flexes Its Media Muscle|work=iSpot TV|date=August 28, 2014|access-date=August 24, 2020}}</ref> and the song was released the next day.


Historically, [[Aristotle]] divided animals [[Aristotle's biology|into those with blood and those without]]. [[Carl Linnaeus]] created the first hierarchical [[Taxonomy (biology)|biological classification]] for animals in 1758 with his ''[[Systema Naturae]]'', which [[Jean-Baptiste Lamarck]] expanded into 14 phyla by 1809. In 1874, [[Ernst Haeckel]] divided the animal kingdom into the multicellular '''Metazoa''' (now [[Synonym (taxonomy)|synonymous]] with Animalia) and the [[Protozoa]], single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as [[molecular phylogenetics]], which are effective at demonstrating the [[evolution]]ary relationships between [[Taxon|taxa]].
==Remixes==
The remix versions of "Animals" featuring with American rappers, [[J. Cole]] released on September 30, 2014,<ref>{{cite web|url=https://hypebeast.com/2014/9/maroon-5-featuring-j-cole-animals-remix|title=Maroon 5 featuring J. Cole - "Animals" (Remix)|work=Hypebeast|last=Montes|first=Patrick|date=September 30, 2014|access-date=July 18, 2019}}</ref> and [[Big Boi]] premiered execlusively on ''[[Pigeons & Planes]]'' website on December 18,<ref name="BigBoiRemix">{{cite magazine|url=https://www.rollingstone.com/music/music-news/hear-big-bois-lusty-new-verse-in-maroon-5s-animals-remix-184277/|title=Hear Big Boi's Lusty New Verse in Maroon 5's 'Animals' Remix|magazine=[[Rolling Stone]]|author=Jon Blistein|date=December 18, 2014|access-date=July 18, 2019}}</ref> both written and produced by Freaky Ta, DCBC and Aftermath artist Me3mo (Sameem Nadeem).


[[Human]]s make [[human uses of animals|use of]] many other animal species for [[Human food|food]] (including [[meat]]<!--no list please-->, [[eggs as food|egg]]s, and [[dairy product]]s), for [[animal product|material]]s (such as [[leather]], [[fur]], and [[wool]]), as [[pet]]s and as [[working animal]]s for [[transportation]], and [[service (economics)|service]]s. [[Dog]]s, the first [[domesticate]]d animal, have been used [[hunting dog|in hunting]], [[guard dog|in security]] and [[dogs in warfare|in warfare]], as have [[equestrianism|horse]]s, [[pigeon post|pigeon]]s and [[falconry|birds of prey]]; while other [[terrestrial animal|terrestrial]] and [[aquatic animal]]s are [[hunt]]ed for sports, trophies or profits. Non-human animals are also an important [[cultural]] element of [[human evolution]], having appeared in [[cave art]]s and [[totem]]s since the earliest times, and are frequently featured in [[mythology]], [[religion]], [[art]]s, [[literature]], [[heraldry]], [[politics]], and [[sport]]s.
==Critical reception==
''[[Rolling Stone]]'' ranked "Animals" at number 32 on its year-end list of the 50 best songs of 2014.<ref>{{cite web|url=https://www.rollingstone.com/music/lists/50-best-songs-of-2014-20141203/jackson-browne-the-birds-of-st-marks-20141202|title=50 Best Songs of 2014|date=December 3, 2014 |publisher=rollingstone.com}}</ref>


==Music video==
==Etymology==
<!--intentional blank line after all headings-->
The music video was released on September 29, 2014, on [[Vevo]]. Directed by [[Samuel Bayer]], the video features [[Adam Levine]] and his wife, [[Behati Prinsloo]]. The other musicians of Maroon 5 (including their touring member [[Sam Farrar]], the first time he appeared in a music video with the band) also make an appearance -- they are seen playing at a nightclub in some scenes of the video. The story of the video is inspired by the film ''[[American Psycho (film)|American Psycho]]'' (2000).<ref>{{cite magazine|url=https://www.billboard.com/articles/columns/pop-shop/6266652/maroon-5-animals-video-adam-levine-behati-prinsloo|title=Watch Adam Levine Become an American Psycho in Maroon 5's 'Animals' Video|magazine=[[Billboard (magazine)|Billboard]]|last=Atkinson|first=Katie|date=September 29, 2014|access-date=November 28, 2019}}</ref>


The word ''animal'' comes from the Latin noun {{Wikt-lang|la|animal}} of the same meaning, which is itself derived from Latin {{Wikt-lang|la|animalis}} 'having breath or soul'.<ref>{{cite book |last=Cresswell |first=Julia |title=The Oxford Dictionary of Word Origins |year=2010 |publisher=[[Oxford University Press]] |location=New York |edition=2nd |isbn=978-0-19-954793-7 |quote='having the breath of life', from anima 'air, breath, life'.}}</ref> The biological definition includes all members of the kingdom Animalia.<ref name=americanheritage_animal>{{cite encyclopedia|title=Animal |encyclopedia=The American Heritage Dictionary |publisher=[[Houghton Mifflin]] |year=2006 |edition=4th}}</ref> In colloquial usage, the term ''animal'' is often used to refer only to nonhuman animals.<ref>{{cite web |website=English Oxford Living Dictionaries |title=animal |url=https://en.oxforddictionaries.com/definition/animal |access-date=26 July 2018 |archive-url=https://web.archive.org/web/20180726233938/https://en.oxforddictionaries.com/definition/animal |archive-date=26 July 2018 |url-status=dead}}</ref><ref>{{cite journal |last1=Boly |first1=Melanie |last2=Seth |first2=Anil K. |last3=Wilke |first3=Melanie |last4=Ingmundson |first4=Paul |last5=Baars |first5=Bernard |last6=Laureys |first6=Steven |last7=Edelman |first7=David |last8=Tsuchiya |first8=Naotsugu |date=2013 |title=Consciousness in humans and non-human animals: recent advances and future directions |journal=[[Frontiers in Psychology]] |volume=4 |pages=625 |doi=10.3389/fpsyg.2013.00625 |pmc=3814086 |pmid=24198791|doi-access=free }}</ref><ref>{{Cite web |website=[[Royal Society]] |url=https://royalsociety.org/topics-policy/publications/2004/non-human-animals/ |title=The use of non-human animals in research |access-date=7 June 2018 |archive-url=https://web.archive.org/web/20180612140908/https://royalsociety.org/topics-policy/publications/2004/non-human-animals/ |archive-date=12 June 2018 |url-status=live }}</ref><ref>{{Cite web |url=https://www.collinsdictionary.com/dictionary/english/nonhuman |title=Nonhuman definition and meaning |website=Collins English Dictionary |access-date=7 June 2018 |archive-url=https://web.archive.org/web/20180612142932/https://www.collinsdictionary.com/dictionary/english/nonhuman |archive-date=12 June 2018 |url-status=live }}</ref> The term ''metazoa'' is derived from Ancient Greek μετα (''meta'') 'after' (in biology, the prefix ''meta-'' stands for 'later') and ζῷᾰ (''zōia'') 'animals', plural of ζῷον ''zōion'' 'animal'.<ref>{{cite encyclopedia |title=Metazoan |dictionary=Merriam-Webster |url=https://www.merriam-webster.com/dictionary/metazoan |access-date=6 July 2022 |archive-date=6 July 2022 |archive-url=https://web.archive.org/web/20220706115538/https://www.merriam-webster.com/dictionary/metazoan |url-status=live }}</ref><ref>{{cite encyclopedia |title=Metazoa |dictionary=Collins |url=https://www.collinsdictionary.com/ko/dictionary/english/metazoa |access-date=6 July 2022 |archive-date=30 July 2022 |archive-url=https://web.archive.org/web/20220730091429/https://www.collinsdictionary.com/ko/dictionary/english/metazoa |url-status=live }} and further [https://www.collinsdictionary.com/ko/dictionary/english/meta meta- (sense 1)] {{Webarchive|url=https://web.archive.org/web/20220730091429/https://www.collinsdictionary.com/ko/dictionary/english/meta |date=30 July 2022 }} and [https://www.collinsdictionary.com/ko/dictionary/english/zoa -zoa] {{Webarchive|url=https://web.archive.org/web/20220730091429/https://www.collinsdictionary.com/ko/dictionary/english/zoa |date=30 July 2022 }}.</ref>
===Synopsis===
[[File:AnimalsScreenshot.jpeg|thumb|right|A scene from the video, presenting a fantasy that features Levine and Prinsloo as obsessed lovers.]]
The video starts with a woman entering a slaughterhouse, where Levine's character works. After she leaves, an [[Infatuation|infatuated]] Levine begins to stalk the woman by following her in the streets and standing outside her apartment in the pouring rain to watch her. He also watches the woman sleep and takes numerous photos of her, which he later trims and places on wires around a dark room. Intercut with this are scenes of a shirtless Levine dripping in fake blood, singing the song inside a meat locker and using animal carcasses for punching bags (an apparent reference to ''[[Rocky]]''). One evening, Levine follows the woman into a nightclub, where he tries to talk to her. Though Prinsloo is amused by Levine and his interest in her, she spends the evening talking to her girlfriends instead. Eventually, Levine is left with no luck, so he goes back to fantasizing about her. After an erotic dream, Levine wakes up in shock and returns to stalking Prinsloo by standing outside her apartment in the rain, watching in a dazed state, leading to the similar opening. The final scenes feature Levine and Prinsloo as obsessed lovers having sex while covered in blood (an apparent reference to ''[[Carrie (1976 film)|Carrie]]'').<ref>{{cite magazine|url=https://www.cosmopolitan.com/entertainment/celebs/news/a31623/maroon5-adam-levine-stalker-animals-video/|title=A Definitive Ranking of All the Creepy Moments in Maroon 5's Disturbing New "Animals" Music Video|magazine=[[Cosmopolitan (magazine)|Cosmopolitan]]|last=Rees|first=Alex|date=September 30, 2014|access-date=October 18, 2019}}</ref>


== Characteristics ==
===Reception and controversy===
The music video was heavily panned by critics and has been condemned for dehumanizing women and glamorizing violence.<ref name="Guardian review">{{cite news|last1=Guardian|title=Guardian review|url=https://www.theguardian.com/commentisfree/2014/oct/01/maroon-5-animals-video-woman-adam-levine|website=Guardian|date=October 2014 |access-date=October 4, 2014}}</ref><ref name=Independent>{{cite web|last1=Independent|title=Independent|url=https://www.independent.co.uk/arts-entertainment/music/news/maroon-5-animals-music-video-attacked-for-promoting-sexual-violence-against-women-9770094.html |archive-url=https://ghostarchive.org/archive/20220507/https://www.independent.co.uk/arts-entertainment/music/news/maroon-5-animals-music-video-attacked-for-promoting-sexual-violence-against-women-9770094.html |archive-date=May 7, 2022 |url-access=subscription |url-status=live|website=Independent|access-date=October 4, 2014}}{{cbignore}}</ref><ref>{{cite web |last1=Clarke |first1=Suzan |title=Maroon 5's Video for 'Animals' Sparks Outrage Over Depiction of Stalking |url=https://abcnews.go.com/Entertainment/maroon-5s-video-animals-sparks-outrage-depiction-stalking/story?id=25932577 |website=ABC News |access-date=23 November 2022 |date=3 October 2014}}</ref> [[Jessica Valenti]] of ''[[The Guardian]]'' criticized the video for attempting to make [[violence against women]] seem "edgy", stating that "there is nothing 'alternative' about showing women being stalked, hunted, raped or killed because it’s something that happens every damn day."<ref name="Guardian review"/> [[Rape, Abuse & Incest National Network|RAINN]] (Rape, Abuse & Incest National Network) released a statement condemning the video, which said that "no one should ever confuse the criminal act of stalking with romance. The trivialisation of these serious crimes, like stalking, should have no place in the entertainment industry."<ref name=Independent/>


[[File:Blastulation.png|thumb|Animals are unique in having the ball of cells of the early [[embryo]] (1) develop into a hollow ball or [[blastula]] (2).]]
In a 2018 interview with ''[[The Independent]]'', Levine dismissed the criticism, calling it "fucking ridiculous", and saying about the video, "It was supposed to be creepy! I play the role of the creep, it's literally a character out of a movie. And the song is about animalistic tendencies, I'm talking about eating someone alive. Use your fucking imagination. It's like watching a horror film and notifying the people who made it to tell them you think they're disgusting. People are sometimes too rooted in reality and they can't differentiate. They take everything too personally."<ref name=ind>{{cite news| url=https://www.independent.co.uk/arts-entertainment/music/features/adam-levine-interview-maroon-5-girls-like-you-video-noel-gallagher-the-voice-us-a8462946.html |archive-url=https://ghostarchive.org/archive/20220507/https://www.independent.co.uk/arts-entertainment/music/features/adam-levine-interview-maroon-5-girls-like-you-video-noel-gallagher-the-voice-us-a8462946.html |archive-date=May 7, 2022 |url-access=subscription |url-status=live| last=O'Connor| first=Roisin| title=Adam Levine: 'I don't know what the f*** Maroon 5 are anymore... we occupy a weird space'| newspaper=[[The Independent]]| date=July 25, 2018| access-date=October 3, 2018}}{{cbignore}}</ref>


Animals have several characteristics that set them apart from other living things. Animals are [[eukaryotic]] and [[multicellular]].<ref name="Avila1995">{{cite book |last=Avila |first=Vernon L. |title=Biology: Investigating Life on Earth |url={{GBurl|id=B_OOazzGefEC|p=767}} |year=1995 |publisher=[[Jones & Bartlett Learning]] |isbn=978-0-86720-942-6 |pages=767–}}</ref> Unlike plants and [[alga]]e, which [[Autotroph|produce their own nutrients]],<ref name=AnimalCells>{{cite web |last=Davidson |first=Michael W. |title=Animal Cell Structure |url=https://micro.magnet.fsu.edu/cells/animalcell.html |access-date=20 September 2007 |archive-url=https://web.archive.org/web/20070920235924/https://micro.magnet.fsu.edu/cells/animalcell.html |archive-date=20 September 2007 |url-status=live}}</ref> animals are [[heterotroph<!--1st use in main text-->]]ic,<ref name="palaeos">{{cite web |title=Palaeos:Metazoa |url=https://palaeos.com/metazoa/metazoa.html |website=Palaeos |access-date=25 February 2018 |archive-url=https://web.archive.org/web/20180228005641/https://palaeos.com/metazoa/metazoa.html |archive-date=28 February 2018 |url-status=dead }}</ref><ref name=Windows>{{cite web |last=Bergman |first=Jennifer |title=Heterotrophs |url=https://www.windows.ucar.edu/tour/link=/earth/Life/heterotrophs.html&edu=high |access-date=30 September 2007 |archive-url=https://web.archive.org/web/20070829051950/https://www.windows.ucar.edu/tour/link%3D/earth/Life/heterotrophs.html%26edu%3Dhigh |archive-date=29 August 2007 |url-status=dead}}</ref> feeding on organic material and digesting it internally.<ref>{{cite journal |last1=Douglas |first1=Angela E. |last2=Raven |first2=John A. |title=Genomes at the interface between bacteria and organelles |journal=[[Philosophical Transactions of the Royal Society B]] |volume=358 |issue=1429 |pages=5–17 |date=January 2003 |pmid=12594915 |pmc=1693093 |doi=10.1098/rstb.2002.1188}}</ref> With very few exceptions, animals [[aerobic respiration|respire aerobically]].{{efn|''[[Henneguya zschokkei]]'' does not have mitochondrial DNA or utilize aerobic respiration.<ref name="CNN-20200226">{{Cite news |url= https://www.cnn.com/2020/02/26/world/first-animal-doesnt-breathe-oxygen-scn-trnd/index.html |title= Scientists discovered the first animal that doesn't need oxygen to live. It's changing the definition of what an animal can be |first= Scottie |last= Andrew |website= CNN |date= 26 February 2020 |access-date= 28 February 2020 |archive-date= 10 January 2022 |archive-url= https://web.archive.org/web/20220110180353/https://www.cnn.com/2020/02/26/world/first-animal-doesnt-breathe-oxygen-scn-trnd/index.html |url-status= live }}</ref>}}<ref name="oxygen">{{cite journal |last1=Mentel |first1=Marek |last2=Martin |first2=William |title=Anaerobic animals from an ancient, anoxic ecological niche |journal=BMC Biology |volume=8 |pages=32 |year=2010 |doi=10.1186/1741-7007-8-32 |pmid=20370917 |pmc=2859860 |doi-access=free }}</ref> All animals are [[Motility|motile]]<ref name=Concepts>{{cite web |url=https://employees.csbsju.edu/SSAUPE/biol116/Zoology/digestion.htm |last=Saupe |first=S. G. |title=Concepts of Biology |access-date=30 September 2007 |archive-url=https://web.archive.org/web/20071121084100/https://employees.csbsju.edu/SSAUPE/biol116/Zoology/digestion.htm |archive-date=21 November 2007 |url-status=live }}</ref> (able to spontaneously move their bodies) during at least part of their [[Biological life cycle|life cycle]], but some animals, such as [[sponge]]s, [[coral]]s, [[mussel]]s, and [[barnacle]]s, later become [[Sessility (motility)|sessile]]. The [[blastula<!--1st use in main text-->]] is a stage in [[Embryogenesis|embryonic development]] that is unique to animals, allowing [[Cellular differentiation|cells to be differentiated]] into specialised tissues and organs.<ref>{{cite book |last=Minkoff |first=Eli C. |title=Barron's EZ-101 Study Keys Series: Biology |year=2008 |publisher=Barron's Educational Series |isbn=978-0-7641-3920-8 |edition=2nd, revised |page=48}}</ref>
==Chart performance==
Commercially in the United States, "Animals" debuted at number 86 on the US [[Billboard Hot 100|''Billboard'' Hot 100]] chart. On October 8, 2014, the song rose from the number 33 to 8,<ref>{{cite web|last1=Trust|first1=Gary|title=Meghan Trainor Leads Hot 100's Record-Setting All-Female Top Five|url=http://www.billboard.com/articles/news/6274312/hot-100-update-meghan-trainor-taylor-swift-iggy-azalea|website=Billboard.com|access-date=October 14, 2014}}</ref> giving the band their tenth top-ten hit overall and their seventh consecutive Hot 100 top-ten hit since the 2011 chart-topping single "[[Moves like Jagger]]". The song reached its million sales mark in the US in November 2014.<ref name=us_sales>{{cite web|url=https://www.yahoo.com/music/taylor-swift-replaces-herself-at-1-103075289246.html|title=Taylor Swift Replaces Herself At #1 on the Hot 100|author=Paul Grein|work=Yahoo! Music|date=November 21, 2014}}</ref> The song peaked at number three on the ''Billboard'' Hot 100 issue dating November 22, 2014 and spent fourteen weeks in the top 10.


=== Structure ===
In other countries, "Animals" made the top-ten progress as well, peaking at number two on the [[Canadian Hot 100]] in Canada. It was also a moderate success in the United Kingdom, where it peaked at number 27 on the [[UK Singles Chart]].


All animals are composed of cells, surrounded by a characteristic [[extracellular matrix]] composed of [[collagen]] and elastic [[glycoprotein]]s.<ref>{{cite book |last1=Alberts |first1=Bruce |last2=Johnson |first2=Alexander |last3=Lewis |first3=Julian |last4=Raff |first4=Martin |last5=Roberts |first5=Keith |last6=Walter |first6=Peter |title=Molecular Biology of the Cell |edition=4th |year=2002 |publisher=[[Garland Science]] |url=https://www.ncbi.nlm.nih.gov/books/NBK26810/ |isbn=978-0-8153-3218-3 |access-date=29 August 2017 |archive-url=https://web.archive.org/web/20161223074013/https://www.ncbi.nlm.nih.gov/books/NBK26810/ |archive-date=23 December 2016 |url-status=live }}</ref> During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as [[Exoskeleton|shells]], [[bone]]s, and [[spicule (sponge)|spicules]].<ref>{{cite book |last=Sangwal |first=Keshra |title=Additives and crystallization processes: from fundamentals to applications |url=https://archive.org/details/additivescrystal00sang |url-access=limited |year=2007 |publisher=[[John Wiley and Sons]] |isbn=978-0-470-06153-4 |page=[https://archive.org/details/additivescrystal00sang/page/n228 212]}}</ref> In contrast, the cells of other multicellular organisms (primarily algae, plants, and [[Fungus|fungi]]) are held in place by cell walls, and so develop by progressive growth.<ref>{{cite book |last=Becker |first=Wayne M. |title=The world of the cell |year=1991 |publisher=[[Benjamin Cummings]] |isbn=978-0-8053-0870-9 |url=https://archive.org/details/worldofcell00beck_0 }}</ref> Animal cells uniquely possess the [[cell junction]]s called [[tight junction]]s, [[gap junction]]s, and [[desmosome]]s.<ref>{{cite book |last=Magloire |first=Kim |title=Cracking the AP Biology Exam, 2004–2005 Edition |year=2004 |publisher=[[The Princeton Review]] |isbn=978-0-375-76393-9 |page=[https://archive.org/details/crackingapbiolog00magl/page/45 45] |url=https://archive.org/details/crackingapbiolog00magl/page/45 }}</ref>
==Live performances==
On October 20, 2014, Maroon 5 performed "Animals" for the 2014 [[NRJ]] Music Tour at [[Maison de la Mutualité]] in [[Paris]], [[France]].<ref>{{cite web|url=https://www.nrj.fr/amp/le-nrj-music-tour-de-paris-avec-maroon-5-et-vos-superstars-nrj-319041|title=The NRJ Music Tour of Paris with Maroon 5 and your NRJ superstars!|work=[[NRJ]]|date=October 21, 2014|access-date=June 14, 2020}}</ref> The same month, Maroon 5 performed the song on ''[[Saturday Night Live]]'' (along with "[[Maps (Maroon 5 song)|Maps]]"),<ref>{{cite web|url=https://www.idolator.com/7565307/maroon-5-performance-snl-animals-maps-saturday-night-live-watch?intexp=1|title=Maroon 5 Perform "Animals" And "Maps" On 'Saturday Night Live': Watch|last=Daw|first=Robert|work=[[Idolator (website)|Idolator]]|date=October 5, 2014|access-date=August 15, 2019}}</ref> as well as ''[[The X Factor (British TV series)|The X Factor]]'',<ref>{{cite web|url=https://metro.co.uk/2014/10/19/the-x-factor-2014-adam-levine-provides-a-welcome-distraction-from-the-results-4912292/|title=The X Factor 2014: Adam Levine provides a welcome distraction from the results|last=Deen|first=Sarah|work=Metro|date=October 19, 2014|access-date=July 19, 2019}}</ref> and the television talk shows ''[[C à vous]]'' (''C to You'') in France and ''[[The Graham Norton Show]]'' in the UK, respectively.<ref>{{cite web|url=https://www.youtube.com/watch?v=0Epy0YlQ6kQ&list=LLHOenn02FqVgT3sEWwMTNeg&index=4123|title=Maroon 5 – Animals in C à vous (22/10/2014)|work=YouTube|date=October 22, 2014 |access-date=June 14, 2020}}</ref><ref>{{cite web|url=https://www.dailymotion.com/video/x28kqwm|title=Maroon 5 - Animals (The Graham Norton Show)|work=[[Dailymotion]]|date=October 25, 2014 |access-date=July 19, 2019}}</ref> On November 10, 2014, Maroon 5 performed the song on the [[The Voice (American season 7)#Week 1: Live playoffs (November 10, 11 & 12)|seventh season]] of ''[[The Voice (American TV series)|The Voice]]''.<ref>{{cite web|url=https://videos.themaroon5.com/the-voice-2014-live-playoffs-maroon-5-animals-video_b3cfa7def.html|work=The Maroon 5 Blog|title=The Voice 2014 Live Playoffs – Maroon 5: "Animals"|access-date=July 19, 2019}}</ref> In December 2014, the band performed "Animals" in a [[Mashup (music)|mash-up]] with "[[This Love (Maroon 5 song)|This Love]]" for ''[[A Very Grammy Christmas]]'' concert (December 5) at the [[Shrine Auditorium]] in Los Angeles, California,<ref>{{cite web|url=https://www.metatube.com/en/videos/259260/A-Very-Grammy-Christmas-Maroon-5-Perform-This-Love-Animals/|title=A Very Grammy Christmas: Maroon 5 Perform "This Love" & "Animals"|work=Metatube|date=December 10, 2014 }}</ref> and performed the song at the [[Jingle Ball Tour 2014|iHeartRadio Jingle Ball Tour 2014]] (December 12) in [[Madison Square Garden]], New York City.<ref>{{cite web|url=https://guardianlv.com/2014/12/iheart-jingle-ball-2014-concert-sang-in-the-holiday-season-right-recap/|title=IHeart Jingle Ball 2014 Concert Sang in the Holiday Season Right [Recap]|last=Cobb|first=Douglas|work=Guardian Liberty Voice|date=December 13, 2014|access-date=August 15, 2019}}</ref>


With few exceptions—in particular, the sponges and [[placozoa]]ns—animal bodies are differentiated into [[biological tissue|tissues]].<ref>{{cite book |last=Starr |first=Cecie |url={{GBurl|id=EXNFwB-O-WUC|p=362}} |title=Biology: Concepts and Applications without Physiology |year=2007 |publisher=Cengage Learning |isbn=978-0-495-38150-1 |pages=362, 365 |access-date=19 May 2020 }}</ref> These include [[muscle]]s, which enable locomotion, and [[nerve tissue]]s, which transmit signals and coordinate the body. Typically, there is also an internal [[Digestion|digestive]] chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians).<ref>{{cite book |last1=Hillmer |first1=Gero |last2=Lehmann |first2=Ulrich |others=Translated by J. Lettau |title=Fossil Invertebrates |year=1983 |publisher=[[Cambridge University Press]] Archive |isbn=978-0-521-27028-1 |page=54 |url={{GBurl|id=9jE4AAAAIAAJ|p=54}} |access-date=8 January 2016 }}</ref>
The band played the track in [[Puerto Rico]] for the first edition of ''[[Victoria's Secret Swim Special]]'', which aired on February 26, 2015.<ref>{{cite web|url=https://www.youtube.com/watch?v=dTD-TcsUJ_g|title=Maroon 5 – Animals (Victoria's Secret Swim Special)|work=YouTube|date=February 27, 2015 }}</ref> Maroon 5 played the song at the Capital One JamFest between 2016 and 2018.<ref>{{cite web|url=http://houston.culturemap.com/news/entertainment/04-04-16-maroon-5-adam-levine-march-madness-music-festival/|title=Maroon 5 thrills gigantic Madness crowd, but even those who didn't get in had a lot fun|work=Culture Map Houston|last=Schroder|first=Reid|date=April 4, 2016|access-date=January 17, 2020}}</ref><ref>{{cite news|url=https://www.mysanantonio.com/entertainment/music-stage/article/Thousands-sing-along-to-Maroon-5-to-close-out-12798111.php|title=Thousands sing along to Maroon 5 to close out March Madness Music Festival|work=My San Antonio|last=Kies|first=Jim|date=April 2, 2018|access-date=January 17, 2020}}</ref> It is part of a setlist for the worldwide concert tour, the [[Maroon V Tour]] (2015–2018).


=== Reproduction and development ===
==Track listing==
{{col-begin}}
{{col-2}}
'''Digital download'''
#"Animals" – 3:51
'''Digital download – Remix featuring J Cole'''
#"Animals" (Remix) (featuring [[J Cole]]) – 4:00
'''Digital download – Remix featuring Big Boi'''
#"Animals" (Remix) (featuring [[Big Boi]]) – 4:00
'''Digital download – Gryffin Remix'''
#"Animals" ([[Gryffin]] Remix) – 5:18
{{col-2}}
'''Digital download – Danny Olson Remix'''
#"Animals" (Danny Olson Remix) – 5:00
'''Digital download – Sammy Bananas Remix'''
#"Animals" (Sammy Bananas Remix) – 5:40
'''Digital download – Zaeden Remix'''
#"Animals" ([[Zaeden]] Remix) – 5:00
{{col-end}}


{{see also|Sexual reproduction#Animals|Asexual reproduction#Examples in animals}}
==Credits and personnel==
Credits adapted from the liner notes of ''V''.<ref name="Notes">{{cite AV media notes|title=[[V (Maroon 5 album)|V]]|year=2014|type= inlay cover|publisher= [[Interscope Records|Interscope]]|page=4|location=United States}}</ref>


[[File:Odonata copulation.jpg|thumb|[[Sexual reproduction]] is nearly universal in animals, such as these [[Dragonfly|dragonflies]].]]
'''Locations'''
*Recorded at [[Conway Recording Studios|Conway Studios]], Los Angeles; [[MXM Studios]], Stockholm
*Mixed at MixStar Studios, [[Virginia Beach, Virginia|Virginia Beach]]


Nearly all animals make use of some form of sexual reproduction.<ref>{{cite book |last=Knobil |first=Ernst |title=Encyclopedia of reproduction, Volume 1 |year=1998 |publisher=Academic Press |isbn=978-0-12-227020-8 |page=[https://archive.org/details/encyclopediaofre0000unse_f1r2/page/315 315] |url=https://archive.org/details/encyclopediaofre0000unse_f1r2/page/315 }}</ref> They produce [[haploid]] [[gamete]]s by [[meiosis]]; the smaller, motile gametes are [[Spermatozoon|spermatozoa]] and the larger, non-motile gametes are [[Egg cell|ova]].<ref>{{cite book |last=Schwartz |first=Jill |title=Master the GED 2011 |year=2010 |publisher=Peterson's |isbn=978-0-7689-2885-3 |page=[https://archive.org/details/petersonsmasterg0000stew_x3f1/page/371 371] |url=https://archive.org/details/petersonsmasterg0000stew_x3f1/page/371 }}</ref> These fuse to form [[zygote]]s,<ref>{{cite book |last=Hamilton |first=Matthew B. |title=Population genetics |url=https://archive.org/details/populationgeneti00hami |url-access=limited |year=2009 |publisher=[[Wiley-Blackwell]] |isbn=978-1-4051-3277-0 |page=[https://archive.org/details/populationgeneti00hami/page/n69 55]}}</ref> which develop via [[mitosis]] into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge.<ref>{{cite book |last1=Ville |first1=Claude Alvin |last2=Walker |first2=Warren Franklin |last3=Barnes |first3=Robert D. |title=General zoology |year=1984 |publisher=Saunders College Pub |isbn=978-0-03-062451-3 |page=467}}</ref> In most other groups, the blastula undergoes more complicated rearrangement.<ref>{{cite book |last1=Hamilton |first1=William James |last2=Boyd |first2=James Dixon |last3=Mossman |first3=Harland Winfield |title=Human embryology: (prenatal development of form and function) |year=1945 |publisher=Williams & Wilkins |page=330}}</ref> It first [[Invagination|invaginates]] to form a [[gastrula]] with a digestive chamber and two separate [[germ layer]]s, an external [[ectoderm]] and an internal [[endoderm]].<ref>{{cite book |last=Philips |first=Joy B. |title=Development of vertebrate anatomy |year=1975 |publisher=Mosby |isbn=978-0-8016-3927-2 |page=[https://archive.org/details/developmentofver0000phil/page/176 176] |url=https://archive.org/details/developmentofver0000phil/page/176 }}</ref> In most cases, a third germ layer, the [[mesoderm]], also develops between them.<ref>{{cite book |title=The Encyclopedia Americana: a library of universal knowledge, Volume 10 |year=1918 |publisher=Encyclopedia Americana Corp. |page=281}}</ref> These germ layers then differentiate to form tissues and organs.<ref>{{cite book |last1=Romoser |first1=William S. |author-link1=William S. Romoser |last2=Stoffolano |first2=J. G. |title=The science of entomology |year=1998 |publisher=WCB McGraw-Hill |isbn=978-0-697-22848-2 |page=156}}</ref>
'''Personnel'''
{{Div col|colwidth=30em}}
*Songwriting&nbsp;– Adam Levine, Shellback, Benjamin Levin
*Production&nbsp;– Shellback
*Lead vocals&nbsp;– Adam Levine
*Instrumentation, background vocals, programming&nbsp;– Shellback
*Mixing&nbsp;– Serban Ghenea
*Vocals recording&nbsp;– Shellback, Max Martin
*Engineering&nbsp;– Noah Passovoy
*Assistant engineers&nbsp;– Eric Eylands, Tim Roberts
*Mix engineer&nbsp;– John Hanes
*Lead and rhythm guitar&nbsp;– James Valentine, Jesse Carmichael
*Bass&nbsp;– Mickey Madden
*Drums and percussion&nbsp;– Matt Flynn
*Keyboards and synthesizers&nbsp;– Jesse Carmichael, PJ Morton
{{Div col end}}


Repeated instances of [[inbreeding|mating with a close relative]] during sexual reproduction generally leads to [[inbreeding depression]] within a population due to the increased prevalence of harmful [[Dominance (genetics)|recessive]] traits.<ref name="pmid19834483">{{cite journal |last1=Charlesworth |first1=D. |last2=Willis |first2=J. H. |title=The genetics of inbreeding depression |journal=[[Nature Reviews Genetics]] |volume=10 |issue=11 |pages=783–796 |year=2009 |pmid=19834483 |doi=10.1038/nrg2664 |s2cid=771357 }}</ref><ref name="pmid3324702">{{cite book |last1=Bernstein |first1=H. |last2=Hopf |first2=F. A. |last3=Michod |first3=R. E. |chapter=The Molecular Basis of the Evolution of Sex |title=Molecular Genetics of Development |series=Advances in Genetics |volume=24 |pages=323–370 |year=1987 |pmid=3324702 |doi=10.1016/s0065-2660(08)60012-7 |isbn=978-0-12-017624-3}}</ref> Animals have evolved numerous mechanisms for [[inbreeding avoidance|avoiding close inbreeding]].<ref name=Pusey>{{cite journal |last1=Pusey |first1=Anne |last2=Wolf |first2=Marisa |title=Inbreeding avoidance in animals |journal=Trends Ecol. Evol. |volume=11 |issue=5 |pages=201–206 |year=1996 |pmid=21237809 |doi=10.1016/0169-5347(96)10028-8|bibcode=1996TEcoE..11..201P }}</ref>
==Charts==
{{col-begin}}
{{col-2}}


Some animals are capable of [[asexual reproduction]], which often results in a genetic clone of the parent. This may take place through [[Fragmentation (reproduction)|fragmentation]]; [[budding]], such as in [[Hydra (genus)|''Hydra'']] and other [[cnidaria]]ns; or [[parthenogenesis]], where fertile eggs are produced without [[mating]], such as in [[aphid]]s.<ref>{{cite book |last1=Adiyodi |first1=K. G. |last2=Hughes |first2=Roger N. |last3=Adiyodi |first3=Rita G. |title=Reproductive Biology of Invertebrates, Volume 11, Progress in Asexual Reproduction |date=July 2002 |publisher=Wiley |page=116 |isbn=978-0-471-48968-9}}</ref><ref>{{cite web |last1=Schatz |first1=Phil |title=Concepts of Biology: How Animals Reproduce |url=https://philschatz.com/biology-concepts-book/contents/m45547.html |publisher=OpenStax College |access-date=5 March 2018 |archive-url=https://web.archive.org/web/20180306022745/https://philschatz.com/biology-concepts-book/contents/m45547.html |archive-date=6 March 2018 |url-status=live }}</ref>
===Weekly charts===

{| class="wikitable sortable plainrowheaders" style="text-align:center;"
== Ecology ==

[[File:Ultramarine Flycatcher (Ficedula superciliaris) Naggar, Himachal Pradesh, 2013 (cropped).JPG|thumb|upright|left|[[Predator]]s, such as this [[ultramarine flycatcher]] (''Ficedula superciliaris''), feed on other animals.]]

Animals are categorised into ecological groups depending on their [[trophic level]]s and [[feeding behaviour|how they consume organic material]]. Such groupings include [[carnivore]]s (further divided into subcategories such as [[piscivore]]s, [[insectivore]]s, [[ovivore]]s, etc.), [[herbivore]]s (subcategorized into [[folivore]]s, [[graminivore]]s, [[frugivore]]s, [[granivore]]s, [[nectarivore]]s, [[algivore]]s, etc.), [[omnivore]]s, [[fungivore]]s, [[scavenger]]s/[[detritivore]]s,<ref>{{cite book |last1=Marchetti |first1=Mauro |last2=Rivas |first2=Victoria |title=Geomorphology and environmental impact assessment |year=2001 |publisher=Taylor & Francis |isbn=978-90-5809-344-8 |page=84}}</ref> and [[parasite]]s.<ref>{{cite book |last=Levy |first=Charles K. |title=Elements of Biology |year=1973 |publisher=[[Appleton-Century-Crofts]] |isbn=978-0-390-55627-1 |page=108}}</ref> [[Biological interaction|Interaction]]s between animals of each [[biome]] form complex [[food web]]s within that [[ecosystem]]. In carnivorous or omnivorous species, [[predation]] is a [[consumer-resource systems|consumer–resource interaction]] where the predator feeds on another organism, its [[prey]],<ref name=Ecology>{{cite book |last1=Begon |first1=M. |last2=Townsend |first2=C. |last3=Harper |first3=J. |date=1996 |title=Ecology: Individuals, populations and communities |edition=Third |publisher=Blackwell Science |isbn=978-0-86542-845-4 |url=https://archive.org/details/ecology00mich }}</ref> who often evolves [[anti-predator adaptation]]s to avoid being fed upon. [[Selective pressure]]s imposed on one another lead to an [[evolutionary arms race]] between predator and prey, resulting in various antagonistic/[[competition (biology)|competitive]] [[coevolution]]s.<ref>{{cite book |last1=Allen |first1=Larry Glen |last2=Pondella |first2=Daniel J. |last3=Horn |first3=Michael H. |title=Ecology of marine fishes: California and adjacent waters |year=2006 |publisher=[[University of California Press]] |isbn=978-0-520-24653-9 |page=428}}</ref><ref>{{cite book |last=Caro |first=Tim |author-link=Tim Caro |title=Antipredator Defenses in Birds and Mammals |date=2005 |publisher=[[University of Chicago Press]] |pages=1–6 and passim}}</ref> Almost all multicellular predators are animals.<ref name="SimpsonCB">{{cite journal |last1=Simpson |first1=Alastair G.B |last2=Roger |first2=Andrew J. |doi=10.1016/j.cub.2004.08.038 |pmid=15341755 |title=The real 'kingdoms' of eukaryotes |journal=Current Biology |volume=14 |issue=17 |pages=R693–696 |year=2004 |s2cid=207051421 |doi-access=free |bibcode=2004CBio...14.R693S }}</ref> Some [[consumer (food chain)|consumers]] use multiple methods; for example, in [[parasitoid wasp]]s, the larvae feed on the hosts' living tissues, killing them in the process,<ref>{{cite journal |last=Stevens |first=Alison N. P. |title=Predation, Herbivory, and Parasitism |journal=Nature Education Knowledge |date=2010 |volume=3 |issue=10 |page=36 |url=https://www.nature.com/scitable/knowledge/library/predation-herbivory-and-parasitism-13261134 |access-date=12 February 2018 |archive-url=https://web.archive.org/web/20170930230324/https://www.nature.com/scitable/knowledge/library/predation-herbivory-and-parasitism-13261134 |archive-date=30 September 2017 |url-status=live }}</ref> but the adults primarily consume nectar from flowers.<ref>{{Cite journal |last1=Jervis |first1=M. A. |last2=Kidd |first2=N. A. C. |date=November 1986 |title=Host-Feeding Strategies in Hymenopteran Parasitoids |journal=Biological Reviews |volume=61 |issue=4 |pages=395–434 |doi=10.1111/j.1469-185x.1986.tb00660.x |s2cid=84430254 }}</ref> Other animals may have very specific [[feeding behaviour]]s, such as [[hawksbill sea turtle]]s which mainly [[Spongivore|eat sponges]].<ref name="ScienceSpongi">{{cite journal |last=Meylan |first=Anne |title=Spongivory in Hawksbill Turtles: A Diet of Glass |journal=Science |volume=239 |issue=4838 |pages=393–395 |date=22 January 1988 |doi=10.1126/science.239.4838.393|pmid=17836872 |jstor=1700236|bibcode=1988Sci...239..393M |s2cid=22971831}}</ref>

[[File:Expl0072 - Flickr - NOAA Photo Library.jpg|thumb|[[Hydrothermal vent]] mussels and shrimps]]
Most animals rely on [[biomass]] and [[biological energy|bioenergy]] produced by [[plant]]s and [[phytoplankton]]s (collectively called [[producer (biology)|producer]]s) through [[photosynthesis]]. Herbivores, as [[consumer (food chain)#Levels of the food chain|primary consumer]]s, eat the plant material directly to digest and absorb the nutrients, while carnivores and other animals on higher [[trophic level]]s indirectly acquire the nutrients by eating the herbivores or other animals that have eaten the herbivores. Animals oxidize [[carbohydrate]]s, [[lipid]]s, [[protein]]s and other biomolecules, which allows the animal to grow and to sustain [[basal metabolism]] and fuel other biological processes such as [[animal locomotion|locomotion]].<ref>{{cite book |title=Understanding Science: Upper Primary |last=Clutterbuck |first=Peter |year=2000 |publisher=Blake Education |isbn=978-1-86509-170-9 |page=9}}</ref><ref>{{cite book |last=Gupta |first=P. K. |title=Genetics Classical To Modern |publisher=Rastogi Publications |isbn=978-81-7133-896-2 |page=26|year=1900 }}</ref><ref>{{cite book |last1=Garrett |first1=Reginald |last2=Grisham |first2=Charles M. |title=Biochemistry |url=https://archive.org/details/biochemistry00rhga |url-access=limited |year=2010 |publisher=Cengage Learning |isbn=978-0-495-10935-8 |page=[https://archive.org/details/biochemistry00rhga/page/n572 535]}}</ref> Some [[benthic]] animals living close to [[hydrothermal vent]]s and [[cold seep]]s on the dark [[seabed|sea floor]] consume organic matter produced through [[chemosynthesis]] (via [[oxidizing]] [[inorganic compound]]s such as [[hydrogen sulfide]]) by [[archaea]] and [[bacteria]].<ref>{{cite book |last1=Castro |first1=Peter |last2=Huber |first2=Michael E. |title=Marine Biology |publisher=McGraw-Hill |year=2007 |edition=7th |page=376 |isbn=978-0-07-722124-9}}</ref>

Animals evolved in the sea. Lineages of arthropods colonised land around the same time as [[land plant]]s, probably between 510 and 471 million years ago during the [[Late Cambrian]] or Early [[Ordovician]].<ref name="Rota-Stabelli2013">{{cite journal |last1=Rota-Stabelli |first1=Omar |last2=Daley |first2=Allison C. |last3=Pisani |first3=Davide |title=Molecular Timetrees Reveal a Cambrian Colonization of Land and a New Scenario for Ecdysozoan Evolution |journal=Current Biology |volume=23 |issue=5 |pages=392–8 |year=2013 |doi-access=free |doi=10.1016/j.cub.2013.01.026 |pmid=23375891|bibcode=2013CBio...23..392R }}</ref> [[Vertebrate]]s such as the [[Sarcopterygii|lobe-finned fish]] ''[[Tiktaalik]]'' started to move on to land in the late [[Devonian]], about 375 million years ago.<ref>{{cite journal |last1=Daeschler |first1=Edward B. |last2=Shubin |first2=Neil H. |last3=Jenkins |first3=Farish A. Jr. |title=A Devonian tetrapod-like fish and the evolution of the tetrapod body plan |journal=[[Nature (journal)|Nature]] |volume=440 |pages=757–763 |date=6 April 2006 |doi=10.1038/nature04639 |pmid=16598249 |issue=7085 |bibcode=2006Natur.440..757D |doi-access=free }}</ref><ref>{{cite journal |author-link=Jennifer A. Clack |last=Clack |first=Jennifer A. |journal=[[Scientific American]] |volume=293 |issue=6 |pages=100–7 |title=Getting a Leg Up on Land |date=21 November 2005 |bibcode=2005SciAm.293f.100C |doi=10.1038/scientificamerican1205-100 |pmid=16323697 }}</ref> Animals occupy virtually all of earth's [[habitat]]s and microhabitats, with [[fauna]]s adapted to salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of other organisms.<ref name="Margulis">{{cite book |last=Margulis |first=Lynn |author1-link=Lynn Margulis |author2=Schwartz, Karlene V. |author3=Dolan, Michael |title=Diversity of Life: The Illustrated Guide to the Five Kingdoms |url={{GBurl|id=8wJXWBMsEOkC|p=115}} |year=1999 |publisher=Jones & Bartlett Learning |isbn=978-0-7637-0862-7 |pages=115–116}}</ref> Animals are however not particularly [[Thermophile|heat tolerant]]; very few of them can survive at constant temperatures above {{convert|50|°C|0|abbr=on}}<ref name="Clarke2014">{{cite journal |last=Clarke |first=Andrew |title=The thermal limits to life on Earth |journal=International Journal of Astrobiology |volume=13 |issue=2 |pages=141–154 |year=2014 |bibcode=2014IJAsB..13..141C |url=https://nora.nerc.ac.uk/id/eprint/507274/1/Clarke.pdf |archive-url=https://web.archive.org/web/20190424155004/https://nora.nerc.ac.uk/id/eprint/507274/1/Clarke.pdf |archive-date=24 April 2019 |url-status=live |doi=10.1017/S1473550413000438|doi-access=free }}</ref> or in the most extreme cold deserts of continental [[Antarctica]].<ref name="bas-land">{{cite web |title=Land animals |url=https://www.bas.ac.uk/about/antarctica/wildlife/land-animals/ |publisher=[[British Antarctic Survey]] |access-date=7 March 2018 |archive-url=https://web.archive.org/web/20181106225451/https://www.bas.ac.uk/about/antarctica/wildlife/land-animals/ |archive-date=6 November 2018 |url-status=live}}</ref>

== Diversity ==

=== Size ===

{{further|Largest organisms|Smallest organisms}}

[[File:Anim1754 - Flickr - NOAA Photo Library (1).jpg|thumb|The [[blue whale]] is the largest animal that has ever lived.]]

The [[blue whale]] (''Balaenoptera musculus'') is the largest animal that has ever lived, weighing up to 190 [[tonne]]s and measuring up to {{convert|33.6|m|ft}} long.<ref name=Wood>{{cite book |last=Wood |first=Gerald |title=The Guinness Book of Animal Facts and Feats |year=1983 |isbn=978-0-85112-235-9 |url=https://archive.org/details/guinnessbookofan00wood |publisher=Enfield, Middlesex : Guinness Superlatives }}</ref><ref>{{cite web |last1=Davies |first1=Ella |title=The longest animal alive may be one you never thought of |url=https://www.bbc.com/earth/story/20160420-the-longest-animal-alive-may-not-be-the-blue-whale |website=BBC Earth |access-date=1 March 2018 |date=20 April 2016 |archive-url=https://web.archive.org/web/20180319073808/https://www.bbc.com/earth/story/20160420-the-longest-animal-alive-may-not-be-the-blue-whale |archive-date=19 March 2018 |url-status=live }}</ref><ref>{{cite web |url=https://www.guinnessworldrecords.com/world-records/largest-mammal |title=Largest mammal |publisher=Guinness World Records |access-date=1 March 2018 |archive-url=https://web.archive.org/web/20180131024019/https://www.guinnessworldrecords.com/world-records/largest-mammal |archive-date=31 January 2018 |url-status=live }}</ref> The largest extant terrestrial animal is the [[African bush elephant]] (''Loxodonta africana''), weighing up to 12.25 tonnes<ref name="Wood"/> and measuring up to {{convert|10.67|m|ft}} long.<ref name=Wood/> The largest terrestrial animals that ever lived were [[titanosaur]] [[Sauropoda|sauropod dinosaurs]] such as ''[[Argentinosaurus]]'', which may have weighed as much as 73 tonnes, and ''Supersaurus'' which may have reached 39 meters.<ref name="Mazzettaetal2004">{{cite journal |last=Mazzetta |first=Gerardo V. |author2=Christiansen, Per |author3=Fariña, Richard A. |year=2004 |title=Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs |journal=Historical Biology |volume=16 |issue= 2–4 |pages=71–83 |doi=10.1080/08912960410001715132 |bibcode=2004HBio...16...71M |citeseerx=10.1.1.694.1650 |s2cid=56028251 }}</ref><ref>{{Cite web |last=Curtice |first=Brian |date=2020 |title=Society of Vertebrate Paleontology |url=https://vertpaleo.org/wp-content/uploads/2021/10/SVP_2021_VirtualBook_final.pdf#page=92 |website=Vertpaleo.org |access-date=30 December 2022 |archive-date=19 October 2021 |archive-url=https://web.archive.org/web/20211019192436/https://vertpaleo.org/wp-content/uploads/2021/10/SVP_2021_VirtualBook_final.pdf#page=92 |url-status=live }}</ref> Several animals are microscopic; some [[Myxozoa]] ([[obligate parasite]]s within the Cnidaria) never grow larger than 20&nbsp;[[Micrometre|μm]],<ref>{{cite web |url=https://tolweb.org/Myxozoa/2460/2008.07.10 |title=Myxozoa |last=Fiala |first=Ivan |date=10 July 2008 |publisher=Tree of Life Web Project |access-date=4 March 2018 |archive-url=https://web.archive.org/web/20180301225416/https://tolweb.org/Myxozoa/2460/2008.07.10 |archive-date=1 March 2018 |url-status=live }}</ref> and one of the smallest species (''Myxobolus shekel'') is no more than 8.5&nbsp;μm when fully grown.<ref>{{cite journal |last1=Kaur |first1=H. |last2=Singh |first2=R. |title=Two new species of Myxobolus (Myxozoa: Myxosporea: Bivalvulida) infecting an Indian major carp and a cat fish in wetlands of Punjab, India |pmc=3235390 |pmid=23024499 |doi=10.1007/s12639-011-0061-4 |volume=35 |issue=2 |year=2011 |journal=Journal of Parasitic Diseases |pages=169–176}}</ref>

=== Numbers and habitats of major phyla ===

<!--We are NOT trying to be comprehensive here, there are plenty of lower-level Wikipedia articles for that-->
The following table lists estimated numbers of described extant species for the major animal phyla,<ref name="Zhang2013">{{cite journal |last=Zhang |first=Zhi-Qiang |title=Animal biodiversity: An update of classification and diversity in 2013. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) |journal=Zootaxa |volume=3703 |issue=1 |date=30 August 2013 |doi=10.11646/zootaxa.3703.1.3 |url=https://biotaxa.org/Zootaxa/article/download/zootaxa.3703.1.3/4273 |page=5 |access-date=2 March 2018 |archive-url=https://web.archive.org/web/20190424154926/https://biotaxa.org/Zootaxa/article/download/zootaxa.3703.1.3/4273 |archive-date=24 April 2019 |url-status=live |doi-access=free }}</ref> along with their principal habitats (terrestrial, fresh water,<ref name=Balian2008>{{cite book |last1=Balian |first1=E. V. |last2=Lévêque |first2=C. |last3=Segers|first3=H.|first4=K. |last4=Martens |title=Freshwater Animal Diversity Assessment |url={{GBurl|id=Dw4H6DBHnAgC|p=628}} |year=2008 |publisher=Springer |isbn=978-1-4020-8259-7 |page=628}}</ref> and marine),<ref name="Hogenboom2016">{{cite web |last1=Hogenboom |first1=Melissa |title=There are only 35 kinds of animal and most are really weird |url=https://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos |publisher=BBC Earth |access-date=2 March 2018 |archive-url=https://web.archive.org/web/20180810141811/https://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos|archive-date=10 August 2018|url-status=live}}</ref> and free-living or parasitic ways of life.<ref name=Poulin2007>{{cite book |last=Poulin |first=Robert |author-link=Robert Poulin (zoologist) |title=Evolutionary Ecology of Parasites |publisher=[[Princeton University Press]] |year=2007 |isbn=978-0-691-12085-0 |page=[https://archive.org/details/evolutionaryecol0000poul/page/6 6] |url=https://archive.org/details/evolutionaryecol0000poul/page/6 }}</ref> Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.<ref name=Felder2009>{{cite book |last1=Felder |first1=Darryl L. |last2=Camp |first2=David K. |title=Gulf of Mexico Origin, Waters, and Biota: Biodiversity |url={{GBurl|id=CphA8hiwaFIC|pg=RA1-PA1111}} |year=2009 |publisher=Texas A&M University Press |isbn=978-1-60344-269-5 |page=1111}}</ref> Using patterns within the [[taxonomy (biology)|taxonomic]] hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.<ref>{{cite web |title=How many species on Earth? About 8.7 million, new estimate says |url=https://www.sciencedaily.com/releases/2011/08/110823180459.htm |access-date=2 March 2018 |date=24 August 2011 |archive-url=https://web.archive.org/web/20180701164954/https://www.sciencedaily.com/releases/2011/08/110823180459.htm |archive-date=1 July 2018 |url-status=live }}</ref><ref name="Mora2011">{{cite journal |last1=Mora |first1=Camilo |last2=Tittensor |first2=Derek P. |last3=Adl |first3=Sina |last4=Simpson |first4=Alastair G.B. |last5=Worm |first5=Boris |editor-last=Mace |editor-first=Georgina M. |title=How Many Species Are There on Earth and in the Ocean? |journal=PLOS Biology |volume=9 |issue=8 |date=23 August 2011 |doi=10.1371/journal.pbio.1001127 |page=e1001127 |pmid=21886479 |pmc=3160336 |doi-access=free }}</ref>{{efn|The application of [[DNA barcoding]] to taxonomy further complicates this; a 2016 barcoding analysis estimated a total count of nearly 100,000 [[insect]] species for [[Canada]] alone, and extrapolated that the global insect fauna must be in excess of 10 million species, of which nearly 2 million are in a single fly family known as gall midges ([[Cecidomyiidae]]).<ref>{{cite journal |last1=Hebert |first1=Paul D.N. |last2=Ratnasingham |first2=Sujeevan |last3=Zakharov |first3=Evgeny V. |last4=Telfer |first4=Angela C. |last5=Levesque-Beaudin |first5=Valerie |last6=Milton |first6=Megan A. |last7=Pedersen |first7=Stephanie |last8=Jannetta |first8=Paul |last9=deWaard |first9=Jeremy R. |title=Counting animal species with DNA barcodes: Canadian insects |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |date=1 August 2016 |volume=371 |issue=1702 |pages=20150333 |doi=10.1098/rstb.2015.0333 |pmid=27481785 |pmc=4971185}}</ref>}}

{|class="wikitable sortable"
|-
|-
! [[Phylum]]
! scope="col"| Chart (2014–2015)
! class="unsortable" |Example<!--image-->
! scope="col"| Peak<br />position
! Described species
! [[Terrestrial animal|Land]]
! [[Marine animals|Sea]]
! [[Fresh water#Aquatic organisms|Freshwater]]
! Free-living
! [[Parasite|Parasitic]]

|-
|-
|'''[[Arthropoda]]'''
!scope="row"| Australia ([[ARIA Charts|ARIA]])<ref>{{cite web |url=http://www.noise11.com/news/the-veronicas-spend-third-week-on-top-of-aria-singles-chart-20141011 |title=The Veronicas Spend Third Week On Top Of ARIA Singles Chart |work=[[Noise11]] |publisher=Noise Network |date=October 11, 2014 |access-date=October 11, 2014 |last=Ryan |first=Gavin}}</ref>
|[[File:European wasp white bg02.jpg|alt=wasp|100px]]
| 62
|align=right data-sort-value="1257000"|1,257,000<ref name="Zhang2013"/>
|Yes 1,000,000<br />([[insect]]s)<ref name="Stork2018">{{cite journal |last=Stork |first=Nigel E. |s2cid=23755007 |title=How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth? |journal=Annual Review of Entomology |volume=63 |issue=1 |date=January 2018 |doi=10.1146/annurev-ento-020117-043348 |pmid=28938083 |pages=31–45 |doi-access=free }} Stork notes that 1m insects have been named, making much larger predicted estimates.</ref>
|Yes >40,000<br />([[Malacostraca|Malac-<br />ostraca]])<ref>{{cite book |year=2002 |series=Zoological catalogue of Australia |volume=19.2A |title=Crustacea: Malacostraca |publisher=[[CSIRO Publishing]] |isbn=978-0-643-06901-5 |chapter=Introduction |last=Poore |first=Hugh F. |pages=1–7 |chapter-url={{GBurl|id=ww6RzBz42-4C|p=1}}}}</ref>
|Yes 94,000<ref name=Balian2008/>
|Yes<ref name="Hogenboom2016"/>
|Yes >45,000{{efn|Not including [[parasitoid]]s.<ref name=Poulin2007/>}}<ref name=Poulin2007/>

|-
|-
|'''[[Mollusca]]'''
{{single chart|Austria|26|artist=Maroon 5|song=Animals|rowheader=true|access-date=February 3, 2015}}
|[[File:Grapevinesnail 01.jpg|alt=snail|100px]]
|align=right data-sort-value="85000" |85,000<ref name="Zhang2013"/><br />107,000<ref name=Nicol1969/>
|Yes 35,000<ref name=Nicol1969>{{cite journal |last=Nicol |first=David |title=The Number of Living Species of Molluscs |journal=Systematic Zoology |volume=18 |issue=2 |date=June 1969 |pages=251–254 |doi=10.2307/2412618 |jstor=2412618 |doi-access=free }}</ref>
|Yes 60,000<ref name=Nicol1969/>
|Yes 5,000<ref name=Balian2008/><br />12,000<ref name=Nicol1969/>
|Yes<ref name="Hogenboom2016"/>
|Yes >5,600<ref name=Poulin2007/>

|-
|-
|'''[[Chordata]]'''
{{single chart|Flanders|47|artist=Maroon 5|song=Animals|rowheader=true|access-date=February 3, 2015}}
|[[File:Lithobates pipiens.jpg|alt=green spotted frog facing right|100px]]
|align=right data-sort-value="70000"|>70,000<ref name="Zhang2013"/><ref>{{Cite journal|last=Uetz|first=P.|title=A Quarter Century of Reptile and Amphibian Databases|url=https://www.researchgate.net/publication/352462027|journal=Herpetological Review|volume=52|pages=246–255|via=ResearchGate|access-date=2 October 2021|archive-date=21 February 2022|archive-url=https://web.archive.org/web/20220221154655/https://www.researchgate.net/publication/352462027_A_Quarter_Century_of_Reptile_and_Amphibian_Databases|url-status=live}}</ref>
|Yes 23,000<ref name="Reaka-Kudla1996">{{cite book |last1=Reaka-Kudla |first1=Marjorie L. |last2=Wilson |first2=Don E. |last3=Wilson |first3=Edward O. |author3-link=E. O. Wilson |title=Biodiversity II: Understanding and Protecting Our Biological Resources |url={{GBurl|id=-X5OAgAAQBAJ|p=90}} |year=1996 |publisher=Joseph Henry Press |isbn=978-0-309-52075-1 |page=90}}</ref>
|Yes 13,000<ref name="Reaka-Kudla1996"/>
|Yes 18,000<ref name=Balian2008/><br />9,000<ref name="Reaka-Kudla1996"/>
|Yes
|Yes 40<br />([[catfish]])<ref>{{cite book |last1=Burton |first1=Derek |last2=Burton |first2=Margaret |title=Essential Fish Biology: Diversity, Structure and Function |url={{GBurl|id=U0o4DwAAQBAJ|p=281}} |year=2017 |publisher=Oxford University Press |isbn=978-0-19-878555-2 |pages=281–282 |quote=[[Trichomycteridae]] ... includes obligate parasitic fish. Thus 17 genera from 2 subfamilies, [[Vandelliinae]]; 4 genera, 9spp. and [[Stegophilinae]]; 13 genera, 31 spp. are parasites on gills (Vandelliinae) or skin (stegophilines) of fish.}}</ref><ref name=Poulin2007/>

|-
|-
|'''[[Platyhelminthes]]'''
{{single chart|Wallonia|22|artist=Maroon 5|song=Animals|rowheader=true|access-date=February 3, 2015}}
|[[File:Pseudoceros dimidiatus.jpg|100px]]
|align=right data-sort-value="29500"|29,500<ref name="Zhang2013"/>
|Yes<ref>{{Cite journal |last=Sluys |first=R. |title=Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies|journal=Biodiversity and Conservation |volume=8 |issue=12 |pages=1663–1681 |doi=10.1023/A:1008994925673 |year=1999|s2cid=38784755 }}</ref>
|Yes<ref name="Hogenboom2016"/>
|Yes 1,300<!--Turbellaria--><ref name=Balian2008/>
|Yes<ref name="Hogenboom2016"/><br />
3,000–6,500<ref name=Pandian>{{cite book |last=Pandian |first=T. J. |title=Reproduction and Development in Platyhelminthes |publisher=CRC Press |year=2020 |isbn=978-1-000-05490-3 |pages=13–14 |url={{GBurl|id=l6rMDwAAQBAJ|pg=PT14}} |access-date=19 May 2020 }}</ref>
|Yes >40,000<ref name=Poulin2007/><br />
4,000–25,000<ref name=Pandian/>

|-
|-
|'''[[Nematoda]]'''
!scope="row"| Bulgaria ([[International Federation of the Phonographic Industry|IFPI]])<ref name=Bulgaria>{{cite web |url=http://www.bamp-bg.org/2009-07-08-09-48-53/nielsen/511-15122014-21122014.html |title=Airplay Top5 - 15.12.2014 - 21.12.2014 |publisher=[[Bulgarian Association of Music Producers]] |access-date=December 17, 2014 |archive-url=https://web.archive.org/web/20141223203722/http://www.bamp-bg.org/2009-07-08-09-48-53/nielsen/511-15122014-21122014.html |archive-date=December 23, 2014 |url-status=dead }}</ref>
|[[File:CelegansGoldsteinLabUNC.jpg|100px]]
| 1
|align=right data-sort-value="25000"|25,000<ref name="Zhang2013"/>
|Yes (soil)<ref name="Hogenboom2016"/>
|Yes 4,000<ref name=Felder2009/>
|Yes 2,000<ref name=Balian2008/>
|Yes<br />11,000<ref name=Felder2009/>
|Yes 14,000<ref name=Felder2009/>

|-
|-
|'''[[Annelida]]'''
{{single chart|Canada|2|artist=Maroon 5|rowheader=true|access-date=August 28, 2014}}
|[[File:Nerr0328.jpg|100px]]
|align=right |17,000<ref name="Zhang2013"/>
|Yes (soil)<ref name="Hogenboom2016"/>
|Yes<ref name="Hogenboom2016"/>
|Yes 1,750<ref name=Balian2008/>
|Yes
|Yes 400<ref name=Poulin2007/>

|-
|-
|'''[[Cnidaria]]'''
{{single chart|Billboardcanadaac|1|artist=Maroon 5|access-date=19 February 2015|rowheader=true}}
|[[File:FFS Table bottom.jpg|alt=Table coral|100px]]
|-
|align=right data-sort-value="16000"|16,000<ref name="Zhang2013"/>
{{single chart|Billboardcanadachrtop40|1|artist=Maroon 5|rowheader=true|access-date=October 9, 2014}}
|-
|
|Yes<ref name="Hogenboom2016"/>
{{single chart|Billboardcanadahotac|1|artist=Maroon 5|rowheader=true|access-date=October 9, 2014}}
|Yes (few)<ref name="Hogenboom2016"/>
|-
|Yes<ref name="Hogenboom2016"/>
{{single chart|CIS|56|artist=Maroon 5|song=Animals|songid=59801|rowheader=true|access-date=October 5, 2021}}
|Yes >1,350<br />([[Myxozoa]])<ref name=Poulin2007/>
|-

{{single chart|Czech Republic|25|year=2014|week=44|rowheader=true|access-date=November 4, 2014}}
|-
{{single chart|Czechdigital|3|year=2015|week=35|rowheader=true|access-date=October 31, 2014}}
|-
{{single chart|Denmark|15|artist=Maroon 5|song=Animals|rowheader=true|access-date=November 4, 2014}}
|-
{{single chart|Finland|4|artist=Maroon 5|song=Animals|rowheader=true|access-date=November 4, 2014}}
|-
{{single chart|France|25|artist=Maroon 5|song=Animals|rowheader=true|access-date=November 4, 2014}}
|-
{{single chart|Germany|11|artist=Maroon 5|song=Animals|songid=1315732|rowheader=true|access-date=October 19, 2018}}
|-
{{single chart|Hungary|2|year=2014|week=48|rowheader=true|access-date=November 4, 2014}}
|-
{{single chart|Hungarytop10|8|year=2014|week=52|rowheader=true|access-date=November 4, 2014}}
|-
|-
|'''[[Porifera]]'''
{{single chart|Ireland|23|year=2014|week=36|rowheader=true|access-date=November 4, 2014}}
|[[File:A colourful Sponge on the Fathom.jpg|100px]]
|-
|align=right data-sort-value="10800"|10,800<ref name="Zhang2013"/>
{{single chart|Israelairplay|5|year=2014|week=47|artist=Maroon 5|song=Animals|rowheader=true|access-date=November 4, 2014}}
|-
|
|Yes<ref name="Hogenboom2016"/>
{{single chart|Italy|8|artist=Maroon 5|song=Animals|rowheader=true|access-date=November 4, 2014}}
|200–300<ref name=Balian2008/>
|-
|Yes
!scope="row"| Lebanon ([[The Official Lebanese Top 20|OLT20]])<ref>{{cite web |url=http://www.olt20.com/Charts#&panel1-1 |title=The Official Lebanese Top 20 |publisher=[[The Official Lebanese Top 20]] |access-date=August 13, 2014 |archive-url=https://web.archive.org/web/20131103163217/http://www.olt20.com/Charts#&panel1-1 |archive-date=November 3, 2013 |url-status=dead }}</ref>
|Yes<ref>{{cite book |last1=Morand |first1=Serge |last2=Krasnov |first2=Boris R. |last3=Littlewood |first3=D. Timothy J. |title=Parasite Diversity and Diversification |url={{GBurl|id=o2t2BgAAQBAJ|p=44}} |year=2015 |publisher=Cambridge University Press |isbn=978-1-107-03765-6 |page=44 |access-date=2 March 2018 }}</ref>
| 2
|-
! scope="row"| [[Mexico Airplay]] (''[[Billboard (magazine)|Billboard]]'')<ref>{{cite magazine|url=https://www.billboard.com/artist/maroon-5/chart-history/mex/|title=Maroon 5 Chart History (Mexico Airplay)|magazine=[[Billboard (magazine)|Billboard]]|access-date=July 3, 2021}}</ref>
| 5
|-
{{single chart|Dutch40|19|artist=Maroon 5|song=Animals|rowheader=true|access-date=September 12, 2014}}
|-
{{single chart|Dutch100|18|artist=Maroon 5|song=Animals|rowheader=true|access-date=September 5, 2014}}
|-
{{single chart|New Zealand|11|artist=Maroon 5|song=Animals|rowheader=true|access-date=October 3, 2014}}
|-
{{single chart|Norway|15|artist=Maroon 5|song=Animals|rowheader=true|access-date=October 3, 2014}}
|-
{{single chart|Poland|4|year=2015|chartid=1530|access-date=January 26, 2014|rowheader=true}}
|-
{{single chart|Scotland|27|date=2014-11-08|rowheader=true|access-date=February 3, 2015}}
|-
{{single chart|Slovakia|34|year=2014|week=43|rowheader=true|access-date=October 28, 2014}}
|-
{{single chart|Slovakdigital|2|year=2014|week=35|rowheader=true|access-date=September 2, 2014}}
|-
! scope="row"| Slovenia ([[SloTop50]])<ref>{{cite web|url=http://www.slotop50.si/Glasbene-lestvice/Tedenske-lestvice/?year=2014&week=50|title=SloTop50 – Slovenian official singles chart|publisher=slotop50.si|access-date=January 31, 2018}}{{Dead link|date=August 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
| align=center|18
|-
{{single chart|South Africa|7|date=2014-11-12|rowheader=true|access-date=September 17, 2015}}
|-
! scope="row"| South Korea ([[Gaon Digital Chart|Gaon]])<ref>{{cite web|url=http://gaonchart.co.kr/chart/digital.php?f_chart_kind_cd=T&f_week=37&f_year=2014&f_type=week |title=Gaon Chart |publisher=[[Gaon Music Chart|Gaon]] |language=ko |access-date=January 13, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20141217200359/http://www.gaonchart.co.kr/chart/digital.php?f_chart_kind_cd=T&f_week=37&f_year=2014&f_type=week |archive-date=December 17, 2014 }}</ref>
| 12
|-
{{single chart|Spain|12|artist=Maroon 5|song=Animals|rowheader=true|access-date=September 3, 2014}}
|-
{{single chart|Sweden|17|artist=Maroon 5|song=Animals|rowheader=true|access-date=September 4, 2014}}
|-
{{single chart|Switzerland|18|artist=Maroon 5|song=Animals|rowheader=true|access-date=September 4, 2014}}
|-
{{single chart|UK|27|date=2014-11-08|rowheader=true|access-date=February 3, 2015}}
|-
{{single chart|Ukraine|3|date=February 9, 2015|rowheader=true|access-date=October 5, 2021}}
|-
{{single chart|Billboardhot100|3|artist=Maroon 5|rowheader=true|access-date=August 28, 2014}}
|-
{{single chart|Billboardadultcontemporary|11|artist=Maroon 5|rowheader=true|access-date=November 3, 2014}}
|-
{{single chart|Billboardadultpopsongs|1|artist=Maroon 5|rowheader=true|access-date=September 30, 2014}}
|-
{{single chart|Billboarddanceairplay|4|artist=Maroon 5|rowheader=true|access-date=November 20, 2014}}
|-
{{single chart|Billboardlatinairplay|32|artist=Maroon 5|rowheader=true|access-date=November 20, 2014}}
|-
{{single chart|Billboardpopsongs|1|artist=Maroon 5|rowheader=true|access-date=September 30, 2014}}
|-
{{single chart|Billboardrhythmic|21|artist=Maroon 5|rowheader=true|access-date=September 30, 2014}}
|}
{{col-2}}


===Year-end charts===
{| class="wikitable sortable plainrowheaders" style="text-align:center;"
|-
! scope="col"| Chart (2014)
! scope="col"| Position
|-
! scope="row"| Canada (Canadian Hot 100)<ref>{{cite magazine|url=http://www.billboard.com/charts/year-end/2014/canadian-hot-100|title=Canadian Hot 100 – Year End 2014|magazine=Billboard|access-date=October 26, 2019}}</ref>
| style="text-align:center;"| 60
|-
! scope="row"| France (SNEP)<ref>{{cite web|url=https://snepmusique.com/les-tops/le-top-de-lannee/top-singles-annee/?categorie=Top%20Single%20de%20l%E2%80%99ann%C3%A9e&annee=2014|title=Top de l'année Top Singles 2014|publisher=SNEP|language=fr|access-date=October 31, 2020}}</ref>
| style="text-align:center;"| 144
|-
! scope="row"| Germany (Official German Charts)<ref>{{cite web |url=https://www.offiziellecharts.de/charts/single-jahr/for-date-2014 |title=Top 100 Single-Jahrescharts|language=de |work=[[GfK Entertainment]] |publisher=offiziellecharts.de |access-date=August 10, 2015}}</ref>
| style="text-align:center;"| 85
|-
! scope="row"| Hungary (Rádiós Top 40)<ref>{{cite web|url=http://slagerlistak.hu/archivum/eves-osszesitett-listak/radios/2014|title=Rádiós Top 100 - hallgatottsági adatok alapján - 2014|access-date=October 25, 2019|publisher=[[Mahasz]]}}</ref>
| style="text-align:center;"| 58
|-
|-
|'''[[Echinodermata]]'''
! scope="row"| Hungary (Single Top 40)<ref>{{cite web|url=http://slagerlistak.hu/archivum/eves-osszesitett-listak/single_db/2014|title=Single Top 100 - eladási darabszám alapján - 2014|access-date=October 25, 2019|publisher=[[Mahasz]]}}</ref>
|[[File:Starfish, Caswell Bay - geograph.org.uk - 409413.jpg|100px]]
| style="text-align:center;"| 64
|align=right data-sort-value="7500"|7,500<ref name="Zhang2013"/>
|
|Yes 7,500<ref name="Zhang2013"/>
|
|Yes<ref name="Hogenboom2016"/>
|
|-
|-
|'''[[Bryozoa]]'''
!scope="row"|Italy (FIMI)<ref>{{cite web|url=http://www.fimi.it/5233|publisher=[[Federazione Industria Musicale Italiana]]|language=it|access-date=January 14, 2015|title=FIMI - Classifiche Annuali 2014 "TOP OF THE MUSIC" FIMI-GfK: un anno di musica italiana|archive-date=January 13, 2015|archive-url=https://web.archive.org/web/20150113005101/http://www.fimi.it/5233|url-status=dead}}</ref>
|[[File:Bryozoan at Ponta do Ouro, Mozambique (6654415783).jpg|100px]]
|align="center"|77
|align=right data-sort-value="6000" |6,000<ref name="Zhang2013"/>
|
|Yes<ref name="Hogenboom2016"/>
|Yes 60–80<ref name=Balian2008/>
|Yes
|
|-
|-
|'''[[Rotifera]]'''
! scope="row"| Netherlands (Dutch Top 40)<ref>[http://www.top40.nl/bijzondere-lijsten/top-100-jaaroverzichten/2014 Top 100-Jaaroverzicht van 2014] (in Dutch). top40.nl. Retrieved January 1, 2015.</ref>
|[[File:20090730 020239 Rotifer.jpg|100px]]
|align="center"|71
|align=right data-sort-value="2000"|2,000<ref name="Zhang2013"/>
|
|Yes >400<ref>{{cite web |last=Fontaneto |first=Diego |title=Marine Rotifers {{!}} An Unexplored World of Richness |url=https://ukmarinesac.org.uk/PDF/rotifers.pdf |publisher=JMBA Global Marine Environment |access-date=2 March 2018 |pages=4–5 |archive-url=https://web.archive.org/web/20180302225409/https://ukmarinesac.org.uk/PDF/rotifers.pdf |archive-date=2 March 2018 |url-status=live }}</ref>
|Yes 2,000<ref name=Balian2008/>
|Yes
|
|-
|-
|'''[[Nemertea]]'''
! scope="row"|Netherlands (Single Top 100)<ref>{{cite web|url=http://dutchcharts.nl/jaaroverzichten.asp?year=2014&cat=s |title= Jaaroverzichten – Single 2014 |publisher= [[Single Top 100]]. Hung Medien |access-date= December 25, 2014 |language= nl}}</ref>
|[[File:Némerte.jpg|100px]]
|align="center"|63
|align=right data-sort-value="1350"|1,350<ref name="Chernyshev_2021">{{cite journal |last1=Chernyshev |first1=A. V. |title=An updated classification of the phylum Nemertea |journal=Invertebrate Zoology |date=September 2021 |volume=18 |issue=3 |pages=188–196 |doi=10.15298/invertzool.18.3.01 |s2cid=239872311 |url=https://www.researchgate.net/publication/354810461 |access-date=18 January 2023 |doi-access=free }}</ref><ref name="Hookabe_2022">{{cite journal |last1=Hookabe |first1=Natsumi |last2=Kajihara |first2=Hiroshi |last3=Chernyshev |first3=Alexei V. |last4=Jimi |first4=Naoto |last5=Hasegawa |first5=Naohiro |last6=Kohtsuka |first6=Hisanori |last7=Okanishi |first7=Masanori |last8=Tani |first8=Kenichiro |last9=Fujiwara |first9=Yoshihiro |last10=Tsuchida |first10=Shinji |last11=Ueshima |first11=Rei |title=Molecular Phylogeny of the Genus Nipponnemertes (Nemertea: Monostilifera: Cratenemertidae) and Descriptions of 10 New Species, With Notes on Small Body Size in a Newly Discovered Clade |journal=Frontiers in Marine Science |date=2022 |volume=9 |doi=10.3389/fmars.2022.906383 |url=https://www.researchgate.net/publication/362813258 |access-date=18 January 2023 |doi-access=free }}</ref>
|
|Yes
|Yes
|Yes
|
|-
|-
|'''[[Tardigrada]]'''
!scope="row"|Sweden (Sverigetopplistan)<ref>{{cite web|url=https://www.sverigetopplistan.se/chart/43?dspy=2014&dspp=1|title=Årslista Singlar – År 2014|publisher=Sverigetopplistan|language=sv|access-date=October 27, 2019}}</ref>
|[[File:Tardigrade (50594282802).jpg|100px]]
|style="text-align:center;"|87
|align=right data-sort-value="1335"|1,335<ref name="Zhang2013"/>
|Yes<ref name="Hickman Diversity 2018">{{cite book |title=Animal Diversity |first1=Cleveland P. |last1=Hickman |first2=Susan L. |last2=Keen |first3=Allan |last3=Larson |first4=David J. |last4=Eisenhour |edition=8th |publisher=McGraw-Hill Education |date=2018 |isbn=978-1-260-08427-6}}</ref><br/>(moist plants)
|Yes
|Yes
|Yes
|
|-
|-
! colspan=8 |{{centre|Total number of described extant species {{as of|2013|lc=y}}: 1,525,728<ref name="Zhang2013"/>}}
!scope="row"|Ukraine Airplay ([[Tophit]])<ref>{{cite web|url=https://tophit.ru/en/chart/ukraine/yearly/2014-01-01/all/all|title=Ukrainian Top Year-End Radio Hits (2014)|publisher=[[Tophit]] |access-date=August 10, 2019}}</ref>
|style="text-align:center;"| 137
|-
!scope="row"|US ''Billboard'' Hot 100<ref>{{cite magazine|url=https://www.billboard.com/charts/year-end/2014/hot-100-songs|title=Hot 100 Songs – Year-End 2014|magazine=Billboard|access-date=October 26, 2019}}</ref>
|style="text-align:center;"|62
|-
!scope="col"| Chart (2015)
!scope="col"| Position
|-
! scope="row"| Canada (Canadian Hot 100)<ref>{{cite magazine|url=http://www.billboard.com/charts/year-end/2015/canadian-hot-100|title=Canadian Hot 100 – Year End 2015|magazine=Billboard|access-date=December 23, 2015}}</ref>
| 41
|-
! scope="row"| France (SNEP)<ref>{{cite web|url=https://snepmusique.com/les-tops/le-top-de-lannee/top-singles-annee/?categorie=Top%20Single%20de%20l%E2%80%99ann%C3%A9e&annee=2015|title=Top de l'année Top Singles 2015|publisher=SNEP|language=fr|access-date=July 4, 2020}}</ref>
| 120
|-
! scope="row"| Hungary (Rádiós Top 40)<ref>{{cite web|url=http://slagerlistak.hu/archivum/eves-osszesitett-listak/radios/2015|title=Rádiós Top 100 - hallgatottsági adatok alapján - 2015|access-date=October 25, 2019|publisher=[[Mahasz]]}}</ref>
| 100
|-
! scope="row"| Italy (FIMI)<ref>{{cite web|url=http://www.fimi.it/news/classifiche-top-of-the-music-2015-fimi-gfk-la-musica-italiana-in-vetta-negli-album-e-nei-singoli-digitali|title=Classifiche "Top of the Music" 2015 FIMI-GfK: La musica italiana in vetta negli album e nei singoli digitali|publisher=[[Federazione Industria Musicale Italiana]]|language=it|access-date=January 13, 2016}}</ref>
| 86
|-
! scope="row"| Spain (PROMUSICAE)<ref name = "SPAYE2015">{{cite web|url=https://www.elportaldemusica.es/lists/top-100-canciones/2015|title=Top 100 Songs Annual 2015|publisher=[[Productores de Música de España]]|language=es|access-date=May 9, 2022}}</ref>
| 85
|-
! scope="row"| US ''Billboard'' Hot 100<ref>{{cite magazine|title=Hot 100: Year End 2015|url=http://www.billboard.com/charts/year-end/2015/hot-100-songs|magazine=Billboard|publisher=billboard.com|access-date=December 23, 2015}}</ref>
|style="text-align:center;"|46
|-
! scope="row"| US Adult Contemporary (''Billboard'')<ref>{{cite magazine|url=https://www.billboard.com/charts/year-end/2015/adult-contemporary-songs|title=Adult Contemporary Songs – Year-End 2015|magazine=Billboard|access-date=September 6, 2019}}</ref>
| 22
|-
! scope="row"| US Adult Top 40 (''Billboard'')<ref>{{cite magazine|url=https://www.billboard.com/charts/year-end/2015/adult-pop-songs|title=Adult Pop Songs – Year-End 2015|magazine=Billboard|access-date=September 6, 2019}}</ref>
| 25
|-
! scope="row"| US Mainstream Top 40 (''Billboard'')<ref>{{cite magazine|url=https://www.billboard.com/charts/year-end/2015/pop-songs|title=Pop Songs – Year End 2015|magazine=Billboard|access-date=August 15, 2019}}</ref>
|style="text-align:center;"|34
|}
|}
{{col-end}}


== Evolutionary origin ==
==Certifications==
<!-- NOTE TO EDITORS: EVEN IF THE SINGLE IS UNDERCERTIFIED BASED ON SALES, PLEASE DO NOT ADD CERTIFICATIONS IT HAS NOT YET RECEIVED, OR SALES FIGURES UNSUPPORTED BY THE CITATION -- WIKIPEDIA IS NOT A REPOSITORY FOR SALES ESTIMATES ADDED TOGETHER BY ATRL/BUZZJACK/UKMIX USERS -->
{{Certification Table Top}}
{{Certification Table Entry|region=Australia|type=single|award=Platinum|number=3|relyear=2014|certyear=2024|access-date=16 April 2024}}
{{Certification Table Entry|region=Brazil|artist=Maroon 5|title=Animals|type=single|award=Diamond|number=3|relyear=2014|certyear=2024|access-date=July 9, 2024}}
{{Certification Table Entry|region=Canada|relyear=2015|certyear=2015|title=Animals|artist=Maroon 5|type=single|award=Platinum|number=2|digital=true}}
{{Certification Table Entry|region=Germany|relyear=2014|relmonth=08|certyear=2022|title=Animals|artist=Maroon 5|type=single|award=Platinum|access-date=November 11, 2022}}
{{Certification Table Entry|region=Italy|relyear=2014|certyear=2014|title=Animals|artist=Maroon 5|type=single|award=Platinum|id=2714|access-date=July 9, 2024}}
{{Certification Table Entry|region=Spain|relyear=2014|certyear=2015|title=Animals|artist=Maroon 5|type=single|award=Platinum|id=maroon-5-animals|access-date=December 25, 2020}}
{{certification Table Entry|type=single|region=Sweden|artist=Maroon 5|title=Animals|award=Platinum|number=2|relyear=2014|certyear=2015|source=artist|access-date=April 22, 2022}}
{{Certification Table Entry|region=United Kingdom|relyear=2015|certyear=2020|title=Animals|artist=Maroon 5|type=single|award=Platinum|id=520-536-1|access-date=July 24, 2020}}
{{Certification Table Entry|region=United States|relyear=2014|certyear=2014|title=Animals|artist=Maroon 5|type=single|award=Platinum|salesamount= 1,000,000|salesref=<ref name=us_sales/>}}
{{Certification Table Separator|title=Streaming}}
{{Certification Table Entry|region=Denmark|title=Animals|artist=Maroon 5|type=single|award=Platinum|certyear=2014|relyear=2014|relmonth=11|certmonth=11|certday=12|streamsonly=true|id=5373|access-date=December 25, 2020}}
{{Certification Table Entry|region=Spain|certyear=2014|relyear=2014|artist=Maroon 5|title=Animals|award=Gold|certref=<ref>{{cite web|access-date=December 14, 2014 |title= Top 100 Streaming - Semana 49: del 1.12.2014 - 7.12.2014|url= http://www.promusicae.es/listas/semana/2715-streaming-semana-49-2014 |publisher= [[PROMUSICAE]]|format = PDF|language = es}}</ref>|type=single|streamsonly=true|refname=SpainStreamCert|access-date=December 25, 2020}}
{{Certification Table Bottom |noshipments=true| streaming=true|streamsonly=true}}


{{Further|Urmetazoan}}
==Release history==

{| class="wikitable plainrowheaders"
Evidence of animals is found as long ago as the [[Cryogenian]] period. [[24-Isopropylcholestane]] (24-ipc) has been found in rocks from roughly 650 million years ago; it is only produced by sponges and [[Pelagophycidae|pelagophyte]] algae. Its likely origin is from sponges based on [[molecular clock]] estimates for the origin of 24-ipc production in both groups. Analyses of pelagophyte algae consistently recover a [[Phanerozoic]] origin, while analyses of sponges recover a [[Neoproterozoic]] origin, consistent with the appearance of 24-ipc in the fossil record.<ref>{{cite journal |last1=Gold |first1=David |display-authors=et al. |title=Sterol and genomic analyses validate the sponge biomarker hypothesis |journal=PNAS |date=22 February 2016 |volume=113 |issue=10 |pages=2684–2689 |doi=10.1073/pnas.1512614113 |doi-access=free |pmid=26903629 |pmc=4790988 |bibcode=2016PNAS..113.2684G }}</ref><ref>{{cite journal |last1=Love |first1=Gordon |display-authors=et al. |title=Fossil steroids record the appearance of Demospongiae during the Cryogenian period |journal=Nature |date=5 February 2009 |volume=457 |issue=7230 |pages=718–721 |doi=10.1038/nature07673|pmid=19194449 |bibcode=2009Natur.457..718L }}</ref>
|-

! scope="col"| Region
The first body fossils of animals appear in the [[Ediacaran]], represented by forms such as ''[[Charnia]]'' and ''[[Spriggina]]''. It had long been doubted whether these fossils truly represented animals,<ref>{{cite journal |last1=Shen |first1=Bing |last2=Dong |first2=Lin |last3=Xiao |first3=Shuhai |last4=Kowalewski |first4=Michał |year=2008 |title=The Avalon Explosion: Evolution of Ediacara Morphospace |journal=Science |volume=319 |issue=5859 |pages=81–84 |doi=10.1126/science.1150279 |pmid=18174439 |bibcode=2008Sci...319...81S |s2cid=206509488 }}</ref><ref>{{cite journal |title=Late Ediacaran trackways produced by bilaterian animals with paired appendages |first1=Zhe |last1=Chen |first2=Xiang |last2=Chen |first3=Chuanming |last3=Zhou |first4=Xunlai |last4=Yuan |first5=Shuhai |last5=Xiao |date=1 June 2018 |journal=Science Advances |volume=4 |issue=6 |pages=eaao6691 |doi=10.1126/sciadv.aao6691 |pmid=29881773 |pmc=5990303 |bibcode=2018SciA....4.6691C }}</ref><ref>{{cite book |last=Schopf |first=J. William |title=Evolution!: facts and fallacies |year=1999 |publisher=Academic Press |isbn=978-0-12-628860-5 |page=[https://archive.org/details/evolutionfactsfa0000unse/page/7 7] |url=https://archive.org/details/evolutionfactsfa0000unse/page/7 }}</ref> but the discovery of the animal lipid [[cholesterol]] in fossils of ''[[Dickinsonia]]'' establishes their nature.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249"/> Animals are thought to have originated under low-oxygen conditions, suggesting that they were capable of living entirely by [[anaerobic respiration]], but as they became specialized for aerobic metabolism they became fully dependent on oxygen in their environments.<ref name="Zimorski2019">{{cite journal |last1=Zimorski |first1=Verena |last2=Mentel |first2=Marek |last3=Tielens |first3=Aloysius G. M. |last4=Martin |first4=William F. |title=Energy metabolism in anaerobic eukaryotes and Earth's late oxygenation |journal=Free Radical Biology and Medicine |volume=140 |pages=279–294 |year=2019 |doi=10.1016/j.freeradbiomed.2019.03.030 |pmid=30935869 |pmc=6856725 }}</ref>
! scope="col"| Date

! scope="col"| Format
Many animal phyla first appear in the [[fossil]] record during the [[Cambrian explosion]], starting about 539 million years ago, in beds such as the [[Burgess shale]].<ref>{{cite web |title=Stratigraphic Chart 2022 |url=https://stratigraphy.org/ICSchart/ChronostratChart2022-02.pdf |publisher=International Stratigraphic Commission |date=February 2022 |access-date=25 April 2022 |archive-date=2 April 2022 |archive-url=https://web.archive.org/web/20220402100018/https://stratigraphy.org/ICSchart/ChronostratChart2022-02.pdf |url-status=live }}</ref> Extant phyla in these rocks include [[mollusc]]s, [[brachiopod]]s, [[onychophora]]ns, [[tardigrade]]s, [[arthropod]]s, [[echinoderm]]s and [[hemichordate]]s, along with numerous now-extinct forms such as the [[predator]]y ''[[Anomalocaris]]''. The apparent suddenness of the event may however be an artifact of the fossil record, rather than showing that all these animals appeared simultaneously.<ref>{{cite journal |last1=Maloof |first1=A. C. |last2=Porter |first2=S. M. |last3=Moore |first3=J. L. |last4=Dudas |first4=F. O. |last5=Bowring |first5=S. A. |last6=Higgins |first6=J. A. |last7=Fike |first7=D. A. |last8=Eddy |first8=M. P. |s2cid=6694681 |title=The earliest Cambrian record of animals and ocean geochemical change |journal=Geological Society of America Bulletin |year=2010 |volume=122 |issue=11–12 |pages=1731–1774 |doi=10.1130/B30346.1 |bibcode=2010GSAB..122.1731M }}</ref><ref>{{cite web |title=New Timeline for Appearances of Skeletal Animals in Fossil Record Developed by UCSB Researchers |url=https://www.ia.ucsb.edu/pa/display.aspx?pkey=2364 |publisher=The Regents of the University of California |access-date=1 September 2014 |date=10 November 2010 |archive-url=https://web.archive.org/web/20140903062054/https://www.ia.ucsb.edu/pa/display.aspx?pkey=2364 |archive-date=3 September 2014 |url-status=live }}</ref><ref>{{cite journal |last=Conway-Morris |first=Simon |author-link=Simon Conway Morris |title=The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied? |journal=The International Journal of Developmental Biology |year=2003 |volume=47 |issue=7–8 |pages=505–515 |pmid=14756326 |url=https://www.ijdb.ehu.es/web/paper.php?doi=14756326 |access-date=28 February 2018 |archive-url=https://web.archive.org/web/20180716111730/https://www.ijdb.ehu.es/web/paper.php?doi=14756326 |archive-date=16 July 2018 |url-status=live }}</ref><ref name="Royal Ontario Museum">{{cite web |title=The Tree of Life |url=https://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php |website=The Burgess Shale |publisher=[[Royal Ontario Museum]] |access-date=28 February 2018 |archive-url=https://web.archive.org/web/20180216054845/https://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php |archive-date=16 February 2018 |url-status=live |date=10 June 2011}}</ref> That view is supported by the discovery of ''[[Auroralumina attenboroughii]]'', the earliest known Ediacaran crown-group cnidarian (557–562 mya, some 20 million years before the Cambrian explosion) from [[Charnwood Forest]], England. It is thought to be one of the earliest [[Predation|predator]]s, catching small prey with its [[nematocyst]]s as modern cnidarians do.<ref name="Dunn Kenchington Parry Clark 2022">{{cite journal |last1=Dunn |first1=F. S. |last2=Kenchington |first2=C. G. |last3=Parry |first3=L. A. |last4=Clark |first4=J. W. |last5=Kendall |first5=R. S. |last6=Wilby |first6=P. R. |title=A crown-group cnidarian from the Ediacaran of Charnwood Forest, UK |journal=Nature Ecology & Evolution |date=25 July 2022 |volume=6 |issue=8 |pages=1095–1104 |doi=10.1038/s41559-022-01807-x |pmid=35879540 |pmc=9349040 |bibcode=2022NatEE...6.1095D }}</ref>
! scope="col"| Version

! scope="col"| Label(s)
Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago.<ref>{{cite book |last1=Campbell |first1=Neil A. |last2=Reece |first2=Jane B. |title=Biology |year=2005 |publisher=Pearson, Benjamin Cummings |isbn=978-0-8053-7171-0 |edition=7th |page=526}}</ref> Early fossils that might represent animals appear for example in the 665-million-year-old rocks of the [[Trezona Formation]] of [[South Australia]]. These fossils are interpreted as most probably being early [[Porifera|sponges]].<ref name=roseMaloof>{{cite journal |title=Possible animal-body fossils in pre-Marinoan limestones from South Australia |journal=Nature Geoscience |volume=3 |pages=653–659 |date=17 August 2010 |doi=10.1038/ngeo934 |issue=9 |bibcode=2010NatGe...3..653M |last1=Maloof |first1=Adam C. |last2=Rose |first2=Catherine V. |last3=Beach |first3=Robert |last4=Samuels |first4=Bradley M. |last5=Calmet |first5=Claire C. |last6=Erwin |first6=Douglas H. |last7=Poirier |first7=Gerald R. |last8=Yao |first8=Nan |last9=Simons |first9=Frederik J. }}</ref>
! scope="col"| {{abbr|Ref.|Reference}}
[[Trace fossil]]s such as tracks and burrows found in the [[Tonian]] period (from 1 gya) may indicate the presence of [[triploblastic]] worm-like animals, roughly as large (about 5&nbsp;mm wide) and complex as earthworms.<ref name=Seilacher1998>{{cite journal |last1=Seilacher |first1=Adolf |author1-link=Adolf Seilacher |last2=Bose |first2=Pradip K. |last3=Pfluger |first3=Friedrich |title=Triploblastic animals more than 1 billion years ago: trace fossil evidence from india |journal=Science |volume=282 |pages=80–83 |date=2 October 1998 |doi=10.1126/science.282.5386.80 |pmid=9756480 |issue=5386 |bibcode=1998Sci...282...80S}}</ref> However, similar tracks are produced by the giant single-celled protist ''[[Gromia sphaerica]]'', so the Tonian trace fossils may not indicate early animal evolution.<ref name=Matz2008>{{cite journal |last1=Matz |first1=Mikhail V. |last2=Frank |first2=Tamara M. |last3=Marshall |first3=N. Justin |last4=Widder |first4=Edith A. |last5=Johnsen |first5=Sönke |title=Giant Deep-Sea Protist Produces Bilaterian-like Traces |journal=Current Biology |volume=18 |issue=23 |pages=1849–54 |date=9 December 2008 |doi=10.1016/j.cub.2008.10.028 |pmid=19026540 |s2cid=8819675 |doi-access=free |bibcode=2008CBio...18.1849M }}</ref><ref name=MSNBC200811>{{cite news |last=Reilly |first=Michael |title=Single-celled giant upends early evolution |newspaper=NBC News |date=20 November 2008 |url=https://www.nbcnews.com/id/wbna27827279 |access-date=5 December 2008 |archive-url=https://web.archive.org/web/20130329062924/https://www.nbcnews.com/id/27827279/ |archive-date=29 March 2013 |url-status=live }}</ref> Around the same time, the layered mats of [[microorganism]]s called [[stromatolite]]s decreased in diversity, perhaps due to grazing by newly evolved animals.<ref name="Bengtson2002OriginsOfPredation">{{Cite encyclopedia |last=Bengtson |first=S. |year=2002 |chapter=Origins and early evolution of predation |encyclopedia=The Paleontological Society Papers |volume=8 |title=The fossil record of predation |editor=Kowalewski, M. |editor2=Kelley, P. H. |pages=289–317 |publisher=[[The Paleontological Society]] |chapter-url=https://www.nrm.se/download/18.4e32c81078a8d9249800021552/Bengtson2002predation.pdf |access-date=3 March 2018 |archive-date=30 October 2019 |archive-url=https://web.archive.org/web/20191030140248/https://www.nrm.se/download/18.4e32c81078a8d9249800021552/Bengtson2002predation.pdf |url-status=live }}</ref> Objects such as sediment-filled tubes that resemble trace fossils of the burrows of wormlike animals have been found in 1.2 gya rocks in North America, in 1.5 gya rocks in Australia and North America, and in 1.7 gya rocks in Australia. Their interpretation as having an animal origin is disputed, as they might be water-escape or other structures.<ref name="Seilacher 20072">{{cite book |last=Seilacher |first=Adolf |author-link=Adolf Seilacher |title=Trace fossil analysis |date=2007 |publisher=Springer |isbn=978-3-540-47226-1 |publication-place=Berlin |pages=176–177 |oclc=191467085}}</ref><ref>{{cite journal |last=Breyer |first=J. A. |year=1995 |title=Possible new evidence for the origin of metazoans prior to 1 Ga: Sediment-filled tubes from the Mesoproterozoic Allamoore Formation, Trans-Pecos Texas |journal=[[Geology (journal)|Geology]] |volume=23 |issue=3 |pages=269–272 |doi=10.1130/0091-7613(1995)023<0269:PNEFTO>2.3.CO;2 |bibcode=1995Geo....23..269B }}</ref>
|-

! scope="row"| Various
<gallery mode="packed" heights="160">
| August 25, 2014
File:DickinsoniaCostata.jpg|''[[Dickinsonia|Dickinsonia costata]]'' from the [[Ediacaran biota]] (c. 635–542 mya) is one of the earliest animal species known.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249">{{cite journal |last1=Bobrovskiy |first1=Ilya |last2=Hope |first2=Janet M. |last3=Ivantsov |first3=Andrey |last4=Nettersheim |first4=Benjamin J. |last5=Hallmann |first5=Christian |last6=Brocks |first6=Jochen J. |title=Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals |journal=Science |volume=361 |issue=6408 |date=20 September 2018 |doi=10.1126/science.aat7228 |pmid=30237355 |pages=1246–1249|bibcode=2018Sci...361.1246B |doi-access=free }}</ref>
| Digital download
File:Auroralumina attenboroughii reconstruction.jpg|''[[Auroralumina attenboroughii]]'', an Ediacaran predator (c.&nbsp;560 mya)<ref name="Dunn Kenchington Parry Clark 2022" />
| rowspan="2"| Original
File:20191203 Anomalocaris canadensis.png|''[[Anomalocaris canadensis]]'' is one of the many animal species that emerged in the [[Cambrian explosion]], starting some 539 mya, and found in the fossil beds of the [[Burgess shale]].
| rowspan="4"| {{hlist|[[222 Records|222]]|[[Interscope Records|Interscope]]}}
</gallery>
| <ref>{{cite web|url=https://www.amazon.com/Animals/dp/B00XDI0V78|title=Animals by Maroon 5|publisher=[[Amazon Music]]|access-date=August 25, 2014}}</ref>

|-
== Phylogeny ==
! scope="row"| United States

| September 23, 2014
{{further|Lists of animals}}
| [[Contemporary hit radio]]

| <ref>{{cite web|url=http://gfa.radioandrecords.com/publishGFA/GFANextPage.asp?sDate=09/23/2014&Format=1 |title=®R&R :: Going For Adds™ :: CHR/Top 40 |access-date=December 9, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150411102100/http://gfa.radioandrecords.com/publishGFA/GFANextPage.asp?sDate=09%2F23%2F2014&Format=1 |archive-date=April 11, 2015 }}</ref>
=== External phylogeny ===
|-

! scope="row"| Various
Animals are [[Monophyly|monophyletic]], meaning they are derived from a common ancestor. Animals are the sister group to the [[choanoflagellate]]s, with which they form the [[Choanozoa]].<ref name="Budd2015">{{cite journal |doi=10.1111/brv.12239 |pmid=26588818 |title=The origin of the animals and a 'Savannah' hypothesis for early bilaterian evolution |journal=[[Biological Reviews]] |volume=92 |issue=1 |pages=446–473 |year=2017 |last1=Budd |first1=Graham E. |last2=Jensen |first2=Sören |doi-access=free }}</ref>
| September 30, 2014
The dates on the [[phylogenetic tree]] indicate approximately how many millions of years ago ({{em|mya}}) the lineages split.<ref>{{cite journal |last1=Peterson |first1=Kevin J. |last2=Cotton |first2=James A. |last3=Gehling |first3=James G. |last4=Pisani |first4=Davide |date=27 April 2008 |title=The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records |journal=Philosophical Transactions of the Royal Society of London B: Biological Sciences |volume=363 |issue=1496 |pages=1435–1443 |doi=10.1098/rstb.2007.2233 |pmid=18192191 |pmc=2614224 }}</ref><ref>{{cite journal |author-link1=Laura Wegener Parfrey |last1=Parfrey |first1=Laura Wegener |last2=Lahr |first2=Daniel J. G. |last3=Knoll |first3=Andrew H. |author-link4=Laura A. Katz |last4=Katz |first4=Laura A. |date=16 August 2011 |title=Estimating the timing of early eukaryotic diversification with multigene molecular clocks |journal=[[Proceedings of the National Academy of Sciences]] |volume=108 |issue=33 |pages=13624–13629 |doi=10.1073/pnas.1110633108 |pmid=21810989 |bibcode=2011PNAS..10813624P |pmc=3158185 |doi-access=free }}</ref><ref>{{cite web |title=Raising the Standard in Fossil Calibration |url=https://fossilcalibrations.org/ |website=Fossil Calibration Database |access-date=3 March 2018 |archive-url=https://web.archive.org/web/20180307054141/https://fossilcalibrations.org/ |archive-date=7 March 2018 |url-status=live }}</ref><ref>{{Cite journal |last1=Laumer |first1=Christopher E. |last2=Gruber-Vodicka |first2=Harald |last3=Hadfield |first3=Michael G. |last4=Pearse |first4=Vicki B. |last5=Riesgo |first5=Ana |last6=Marioni |first6=John C. |last7=Giribet |first7=Gonzalo |year=2018 |title=Support for a clade of Placozoa and Cnidaria in genes with minimal compositional bias |journal=eLife |volume=2018;7 |pages=e36278 |doi=10.7554/eLife.36278 |pmid=30373720 |pmc=6277202 |doi-access=free }}</ref><ref>{{cite journal |last1=Adl |first1=Sina M. |last2=Bass |first2=David |last3=Lane |first3=Christopher E. |last4=Lukeš |first4=Julius |last5=Schoch |first5=Conrad L. |last6=Smirnov |first6=Alexey |last7=Agatha |first7=Sabine |last8=Berney |first8=Cedric |last9=Brown |first9=Matthew W. |date=2018 |title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes |journal=Journal of Eukaryotic Microbiology |volume=66 |issue=1 |pages=4–119 |doi=10.1111/jeu.12691|pmid=30257078 |pmc=6492006 }}</ref>
| Digital download

| rowspan="2"| Remix featuring [[J. Cole]]
Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines.<ref name="Ros-Rocher Pérez-Posada Leger Ruiz-Trillo 2021">{{cite journal |last1=Ros-Rocher |first1=Núria |last2=Pérez-Posada |first2=Alberto |last3=Leger |first3=Michelle M. |last4=Ruiz-Trillo |first4=Iñaki |title=The origin of animals: an ancestral reconstruction of the unicellular-to-multicellular transition |journal=Open Biology |publisher=The Royal Society |volume=11 |issue=2 |year=2021 |page=200359 |doi=10.1098/rsob.200359|pmid=33622103 |pmc=8061703 }}</ref>
| <ref>{{cite web|url=https://music.apple.com/us/album/animals-remix-feat-j-cole-single/1445278671|title=Maroon 5 – Animals (Remix) (feat. J. Cole)|work=[[Apple Music]]|access-date=May 17, 2020}}</ref>

|-
{{Clade |style=font-size:100%; line-height:100%
! scope="row"| United States
|label1=[[Opisthokonta]] |sublabel1=1300 mya
| October 21, 2014
|1={{Clade
| [[Rhythmic contemporary]] radio
|1=[[Holomycota]] (inc. fungi) [[File:Asco1013.jpg|60 px]]
| <ref>{{cite web|url=http://www.allaccess.com/top40-rhythmic/future-releases|archive-url=https://web.archive.org/web/20141007231512/http://www.allaccess.com/top40-rhythmic/future-releases|title=Top 40 Rhythmic Future Releases - R&B Song and Hip-Hop Music Release Dates - ...|archive-date=October 7, 2014|work=All Access|access-date=December 9, 2015}}</ref>
|label2=[[Holozoa]] |sublabel2=1100 mya
|-
|2={{Clade |state=dashed
! scope="row"| Italy
|1=[[Ichthyosporea]] [[File:Abeoforma whisleri-2.jpg|50 px]]
| November 7, 2014
|2=[[Pluriformea]] [[File:Corallochytrium limacisporum.png|50 px]]
| Contemporary hit radio
|label3=[[Filozoa]]
| Original
|3={{Clade
| rowspan="2"| [[Universal Music Group|Universal]]
|1=[[Filasterea]] [[File:Ministeria vibrans.jpeg|60 px]]
| <ref>{{Cite web|url=https://radiodate.it/radio-date/maroon-5-animals-92568-07-11-2014-radiodate/|title=Maroon 5 – "Animals" (Radio Date: 7/11/2014)|website=radiodate.it}}</ref>
|label2=[[Choanozoa]] |sublabel2=950 mya
|-
|2={{Clade
! scope="row"| Germany
|label1=[[Choanoflagellate]]a |1=[[File:Desmarella moniliformis.jpg|60 px]]
| November 14, 2014
|label2 ='''Animalia''' |sublabel2=760 mya |2= [[File:Polychaeta (no) 2.jpg|60 px]]
| [[CD single|CD]]
}}
| {{hlist|Original|Remix featuring J. Cole}}
}}
| <ref>{{cite web|url=https://www.amazon.de/Animals-2-Track-Maroon-5/dp/B00OUF57A4|title=Animals (2-Track)|website=Amazon Germany |access-date=December 9, 2015}}</ref>
}}
|-
}}
! scope="row" rowspan="2"| Various
}}
| rowspan="2"| November 17, 2014

| rowspan="2"| {{hlist|Digital download|[[streaming]]}}
=== Internal phylogeny ===
| [[Gryffin]] Remix
{{anchor|basal}}
| rowspan="3"| {{hlist|222|Interscope}}

| <ref>{{cite web|url=https://open.spotify.com/album/3PSx9VTrfoKURlEAu8rZBe|title=Animals (Gryffin Remix) - Single by Maroon 5|work=[[Spotify]]|date=November 17, 2014 |access-date=June 5, 2022}}</ref>
The most basal animals, the [[Porifera]], [[Ctenophora]], [[Cnidaria]], and [[Placozoa]], have body plans that lack [[Symmetry in biology|bilateral symmetry]]. Their relationships are still disputed; the sister group to all other animals could be the Porifera or the Ctenophora,<ref name="Kapli_2020">{{cite journal |last1=Kapli |first1=Paschalia |last2=Telford |first2=Maximilian J. |title=Topology-dependent asymmetry in systematic errors affects phylogenetic placement of Ctenophora and Xenacoelomorpha |journal=Science Advances |date=11 December 2020 |volume=6 |issue=10 |pages=eabc5162 |doi=10.1126/sciadv.abc5162 |pmid=33310849 |pmc=7732190 |bibcode=2020SciA....6.5162K |doi-access=free }}</ref> both of which lack [[hox gene]]s, which are important for [[Evolutionary developmental biology#Gene toolkit|body plan development]].<ref name="Giribet 2016">{{cite journal |last=Giribet |first=Gonzalo |title=Genomics and the animal tree of life: conflicts and future prospects |journal=[[Zoologica Scripta]] |volume=45 |date=27 September 2016 |doi=10.1111/zsc.12215 |pages=14–21 |doi-access=free}}</ref><!--Giribet 2016 is a reliable review source, not taking sides; please do not add any primary sources here-->
|-

| Sammy Bananas Remix
Hox genes are found in the Placozoa,<ref>{{Cite web |url=https://emb.carnegiescience.edu/sites/emb.carnegiescience.edu/files/evodevo12.pdf |title=Evolution and Development |date=1 May 2012 |website=Carnegie Institution for Science Department of Embryology |page=38 |archive-url=https://web.archive.org/web/20140302084415/https://emb.carnegiescience.edu/sites/emb.carnegiescience.edu/files/evodevo12.pdf |archive-date=2 March 2014 |url-status=dead |access-date=4 March 2018}}</ref><ref name=Dellaporta2004>{{cite journal |last1=Dellaporta |first1=Stephen |last2=Holland |first2=Peter |last3=Schierwater |first3=Bernd |last4=Jakob |first4=Wolfgang |last5=Sagasser |first5=Sven |last6=Kuhn |first6=Kerstin |title=The Trox-2 Hox/ParaHox gene of Trichoplax (Placozoa) marks an epithelial boundary |journal=Development Genes and Evolution |volume=214 |issue=4 |date=April 2004 |doi=10.1007/s00427-004-0390-8 |pmid=14997392 |pages=170–175|s2cid=41288638 }}</ref> Cnidaria,<ref>{{cite journal |last1=Finnerty |first1=John |title=Cnidarians Reveal Intermediate Stages in the Evolution of Hox Clusters and Axial Complexity |journal=American Zoologist |date=June 2001 |volume=41 |issue=3 |pages=608–620 |doi=10.1093/icb/41.3.608}}</ref> and Bilateria.<ref name="Peterson2001">{{cite journal |doi=10.1046/j.1525-142x.2001.003003170.x |pmid=11440251 |title=Animal phylogeny and the ancestry of bilaterians: Inferences from morphology and 18S rDNA gene sequences |journal=Evolution and Development |volume=3 |issue=3 |pages=170–205 |year=2001 |last1=Peterson |first1=Kevin J. |last2=Eernisse |first2=Douglas J|citeseerx=10.1.1.121.1228 |s2cid=7829548 }}</ref><ref name="KraemerEis2016">{{cite journal |title=A catalogue of Bilaterian-specific genes – their function and expression profiles in early development |year=2016 |last1=Kraemer-Eis |first1=Andrea |last2=Ferretti |first2=Luca |last3=Schiffer |first3=Philipp |last4=Heger |first4=Peter |last5=Wiehe |first5=Thomas |journal=bioRxiv |doi=10.1101/041806 |s2cid=89080338 |url=https://www.biorxiv.org/content/biorxiv/early/2016/03/19/041806.full.pdf |archive-url=https://web.archive.org/web/20180226032414/https://www.biorxiv.org/content/biorxiv/early/2016/03/19/041806.full.pdf |archive-date=26 February 2018 |url-status=live }}</ref> 6,331 groups of [[gene]]s common to all living animals have been identified; these may have arisen from a single [[#Phylogeny|common ancestor]] that lived [[Cryogenian|650 million years ago]] in the [[Precambrian]]. 25 of these are novel core gene groups, found only in animals; of those, 8 are for essential components of the [[Wnt signaling pathway|Wnt]] and [[TGF-beta]] signalling pathways which may have enabled animals to become multicellular by providing a pattern for the body's system of axes (in three dimensions), and another 7 are for [[transcription factor]]s including [[homeodomain]] proteins involved in the [[evo-devo gene toolkit|control of development]].<ref name="Zimmer2018">{{cite news |last=Zimmer |first=Carl |author-link=Carl Zimmer |title=The Very First Animal Appeared Amid an Explosion of DNA |url=https://www.nytimes.com/2018/05/04/science/first-animal-genes-evolution.html |date=4 May 2018 |newspaper=[[The New York Times]] |access-date=4 May 2018 |archive-url=https://web.archive.org/web/20180504170120/https://www.nytimes.com/2018/05/04/science/first-animal-genes-evolution.html |archive-date=4 May 2018 |url-status=live }}</ref><ref name="Paps2018">{{cite journal |last1=Paps |first1=Jordi |last2=Holland |first2=Peter W. H. |title=Reconstruction of the ancestral metazoan genome reveals an increase in genomic novelty |date=30 April 2018 |journal=[[Nature Communications]] |volume=9 |pages=1730 |number=1730 (2018) |doi=10.1038/s41467-018-04136-5 |pmid=29712911 |pmc=5928047 |bibcode=2018NatCo...9.1730P }}</ref>
| <ref>{{cite web|url=https://open.spotify.com/album/3fU6iUgBANYfPcXtKvWuFn|title=Animals (Sammy Bananas Remix) - Single by Maroon 5|work=Spotify|date=November 17, 2014 |access-date=June 5, 2022}}</ref>

|-
Giribet and Edgecombe (2020) provide what they consider to be a consensus internal phylogeny of the animals, embodying uncertainty about the structure at the base of the tree (dashed lines).<ref name=Giribet-2020>{{cite book |last1=Giribet |first1=G. |last2=Edgecombe |first2=G.D. |title=The Invertebrate Tree of Life |year=2020 |publisher=[[Princeton University Press]] |url={{GBurl|id=YHetDwAAQBAJ|p=21}} |page=21 |isbn=978-0-6911-7025-1 |access-date=27 May 2023 }}</ref>
! scope="row"| United States

| December 18, 2014
{{Clade |style = font-size:100%; line-height:100%
| Digital download
|label1='''Animalia''' |sublabel1=''[[Multicellular organism|multicellular]]''
| Remix featuring [[Big Boi]]
|1={{Clade
| <ref name="BigBoiRemix"/>
|1=[[Porifera]] [[File:Estonian Museum of Natural History - Sponge.png|60 px]] |state=dashed
|-
|2=[[Ctenophora]] [[File:Mnemiopsis leidyi 247259012.png|60 px]]
|}
|label3=[[ParaHoxozoa]] |sublabel3=''[[hox gene]]s''
|3={{clade
|1=[[Placozoa]] [[File:Trichoplax adhaerens photograph (no background).png|60 px]] |state=dashed
|2=[[Cnidaria]] <span style="{{MirrorH}}">[[File:Jellyfish, Shaw Ocean Discovery Centre (7201323966).png|70px]]</span>
|label3=[[Bilateria]] |sublabel3=''[[bilateral symmetry|symm.]] embryo''
|3={{clade
|1=[[Xenacoelomorpha]] [[File:Proporus sp. (no background).png|55 px]]
|label2=[[Nephrozoa]]
|2={{clade
|label1=[[Deuterostomia]]
|1={{clade
|1=[[Ambulacraria]] [[File:Echinaster serpentarius (USNM E28192) 001.png|50 px]]
|2=[[Chordata]] [[File:Cyprin carpi 090613-0329 tdp.png|60 px]]
}}
|label2 =[[Protostomia]] |sublabel2=''[[blastopore]] mouth''
|2={{clade
|1=[[Ecdysozoa]] [[File:Aptostichus simus Monterey County.jpg|60px]]
|2=[[Spiralia]] <span style="{{MirrorH}}">[[File:Grapevinesnail 01a.jpg|60px]]</span>
}}
}}
}}
}}
}}
}}

An alternative phylogeny, from Kapli and colleagues (2021), proposes a clade [[Xenambulacraria]] for the Xenacoelamorpha + Ambulacraria; this is either within Deuterostomia, as sister to Chordata, or the Deuterostomia are recovered as paraphyletic, and Xenambulacraria is sister to the proposed clade [[Centroneuralia]], consisting of Chordata + Protostomia.<!--both trees are illustrated in Xenambulacraria, no need to repeat them here.--><ref name="Kapli 2021">{{Cite journal |last1=Kapli |first1=Paschalia |last2=Natsidis |first2=Paschalis |last3=Leite |first3=Daniel J. |last4=Fursman |first4=Maximilian |last5=Jeffrie |first5=Nadia |last6=Rahman |first6=Imran A. |last7=Philippe |first7=Hervé |last8=Copley |first8=Richard R. |last9=Telford |first9=Maximilian J. |date=19 March 2021 |title=Lack of support for Deuterostomia prompts reinterpretation of the first Bilateria |journal=Science Advances |volume=7 |issue=12 |pages=eabe2741 |doi=10.1126/sciadv.abe2741 |pmc=7978419 |pmid=33741592 |bibcode=2021SciA....7.2741K }}</ref>

=== Non-bilateria ===

[[File:Elephant-ear-sponge.jpg|thumb|upright|Non-bilaterians include sponges (centre) and corals (background).]]

Several animal phyla lack bilateral symmetry. These are the [[Porifera]] (sea sponges), [[Placozoa]], [[Cnidaria]] (which includes [[jellyfish]], [[sea anemone]]s, and corals), and [[Ctenophora]] (comb jellies).

Sponges are physically very distinct from other animals, and were long thought to have diverged first, representing the oldest animal phylum and forming a [[sister clade]] to all other animals.<ref>{{cite book |last1=Bhamrah |first1=H. S. |last2=Juneja |first2=Kavita |title=An Introduction to Porifera |year=2003 |publisher=Anmol Publications |isbn=978-81-261-0675-2 |page=58}}</ref> Despite their morphological dissimilarity with all other animals, genetic evidence suggests sponges may be more closely related to other animals than the comb jellies are.<ref name="Schultz-2023">{{Cite journal |last1=Schultz |first1=Darrin T. |last2=Haddock |first2=Steven H. D. |last3=Bredeson |first3=Jessen V. |last4=Green |first4=Richard E. |last5=Simakov |first5=Oleg |last6=Rokhsar |first6=Daniel S. |date=17 May 2023 |title=Ancient gene linkages support ctenophores as sister to other animals |url=https://rdcu.be/dcJSY |journal=Nature |volume=618 |issue=7963 |pages=110–117 |doi=10.1038/s41586-023-05936-6 |pmid=37198475 |s2cid=258765122 |pmc=10232365 |bibcode=2023Natur.618..110S }}</ref><ref>{{Cite journal |last1=Whelan |first1=Nathan V. |last2=Kocot |first2=Kevin M. |last3=Moroz |first3=Tatiana P. |last4=Mukherjee |first4=Krishanu |last5=Williams |first5=Peter |last6=Paulay |first6=Gustav |last7=Moroz |first7=Leonid L. |last8=Halanych |first8=Kenneth M. |date=9 October 2017 |title=Ctenophore relationships and their placement as the sister group to all other animals |url=https://rdcu.be/dcJS3 |journal=Nature Ecology & Evolution |volume=1 |issue=11 |pages=1737–1746 |doi=10.1038/s41559-017-0331-3 |pmid=28993654 |pmc=5664179 |bibcode=2017NatEE...1.1737W }}</ref> Sponges lack the complex organization found in most other animal phyla;<ref>{{cite book |last=Sumich |first=James L. |title=Laboratory and Field Investigations in Marine Life |year=2008 |publisher=Jones & Bartlett Learning |isbn=978-0-7637-5730-4 |page=67}}</ref> their cells are differentiated, but in most cases not organised into distinct tissues, unlike all other animals.<ref>{{cite book |last=Jessop |first=Nancy Meyer |title=Biosphere; a study of life |year=1970 |publisher=[[Prentice-Hall]] |page=428}}</ref> They typically feed by drawing in water through pores, filtering out small particles of food.<ref>{{cite book |last=Sharma |first=N. S. |title=Continuity And Evolution Of Animals |year=2005 |publisher=Mittal Publications |isbn=978-81-8293-018-6 |page=106}}</ref>

The comb jellies and Cnidaria are radially symmetric and have digestive chambers with a single opening, which serves as both mouth and anus.<ref>{{cite book |title=A Living Bay: The Underwater World of Monterey Bay |year=2000 |publisher=University of California Press |isbn=978-0-520-22149-9 |last1=Langstroth |first1=Lovell |last2=Langstroth |first2=Libby |editor-last=Newberry |editor-first=Todd |page=[https://archive.org/details/livingbayunderwa0000lang/page/244 244] |url=https://archive.org/details/livingbayunderwa0000lang/page/244 }}</ref> Animals in both phyla have distinct tissues, but these are not organised into discrete [[organ (anatomy)|organs]].<ref>{{cite book |last=Safra |first=Jacob E. |title=The New Encyclopædia Britannica, Volume 16 |year=2003 |publisher=Encyclopædia Britannica |isbn=978-0-85229-961-6 |page=523}}</ref> They are [[diploblastic]], having only two main germ layers, ectoderm and endoderm.<ref>{{cite book |last=Kotpal |first=R.L. |title=Modern Text Book of Zoology: Invertebrates |publisher=Rastogi Publications |isbn=978-81-7133-903-7 |page=184 |year=2012 }}</ref>

The tiny placozoans have no permanent digestive chamber and no symmetry; they superficially resemble amoebae.<ref>{{cite book |last=Barnes |first=Robert D. |year=1982 |title=Invertebrate Zoology |publisher=Holt-Saunders International |pages=84–85 |isbn=978-0-03-056747-6}}</ref><ref>{{cite web |author=<!--"A.G.C."--> |title=Introduction to Placozoa |url=https://www.ucmp.berkeley.edu/phyla/placozoa/placozoa.html |publisher=UCMP Berkeley |access-date=10 March 2018 |archive-url=https://web.archive.org/web/20180325202849/https://www.ucmp.berkeley.edu/phyla/placozoa/placozoa.html |archive-date=25 March 2018 |url-status=live }}</ref> Their phylogeny is poorly defined, and under active research.<ref name="Schultz-2023" /><ref>{{Cite journal |last1=Srivastava |first1=Mansi |last2=Begovic |first2=Emina |last3=Chapman |first3=Jarrod |last4=Putnam |first4=Nicholas H. |last5=Hellsten |first5=Uffe |last6=Kawashima |first6=Takeshi |last7=Kuo |first7=Alan |last8=Mitros |first8=Therese |last9=Salamov |first9=Asaf |last10=Carpenter |first10=Meredith L. |last11=Signorovitch |first11=Ana Y. |last12=Moreno |first12=Maria A. |last13=Kamm |first13=Kai |last14=Grimwood |first14=Jane |last15=Schmutz |first15=Jeremy |date=1 August 2008 |title=The Trichoplax genome and the nature of placozoans |journal=Nature |volume=454 |issue=7207 |pages=955–960 |doi=10.1038/nature07191 |pmid=18719581 |bibcode=2008Natur.454..955S |s2cid=4415492 |doi-access=free }}</ref>

=== Bilateria ===

{{main|Bilateria|Symmetry (biology)#Bilateral symmetry}}

[[File:Bilaterian body plan.svg|thumb|left|upright=1.35|Idealised [[bilateria]]n body plan.{{efn|Compare [[:File:Annelid redone w white background.svg]] for a more specific and detailed model of a particular phylum with this general body plan.}} With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the [[cephalisation|basis of the head]]. Opposed circular and longitudinal muscles enable [[peristalsis|peristaltic motion]].]]

The remaining animals, the great majority—comprising some 29 phyla and over a million species—form a [[clade]], the Bilateria, which have a bilaterally symmetric [[body plan]]. The Bilateria are [[Triploblasty|<!--this is the primary location for this wikilink-->triploblastic]], with three well-developed germ layers, and their tissues [[Organogenesis|form distinct organs]]. The digestive chamber has two openings, a mouth and an anus, and there is an internal body cavity, a [[coelom]] or pseudocoelom. These animals have a head end (anterior) and a tail end (posterior), a back (dorsal) surface and a belly (ventral) surface, and a left and a right side.<ref name="Minelli2009"/><ref name=Brusca2016/>

Having a front end means that this part of the body encounters stimuli, such as food, favouring [[cephalisation]], the development of a head with [[sense organ]]s and a mouth. Many bilaterians have a combination of circular [[muscle]]s that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body;<ref name=Brusca2016/> these enable soft-bodied animals with a [[hydrostatic skeleton]] to move by [[peristalsis]].<ref name=Quillin>{{cite journal |last=Quillin |first=K. J. |title=Ontogenetic scaling of hydrostatic skeletons: geometric, static stress and dynamic stress scaling of the earthworm lumbricus terrestris |journal=[[Journal of Experimental Biology]] |volume=201 |issue=12 |pages=1871–1883 |date=May 1998 |doi=10.1242/jeb.201.12.1871 |pmid=9600869 |url=https://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=9600869 |doi-access=free |access-date=4 March 2018 |archive-date=17 June 2020 |archive-url=https://web.archive.org/web/20200617135617/https://jeb.biologists.org/content/201/12/1871.long |url-status=live }}</ref> They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary [[larva]]e which swim with [[cilia]] and have an apical organ containing sensory cells. However, over evolutionary time, descendant spaces have evolved which have lost one or more of each of these characteristics. For example, adult echinoderms are radially symmetric (unlike their larvae), while some [[Helminths|parasitic worms]] have extremely simplified body structures.<ref name="Minelli2009">{{cite book |last=Minelli |first=Alessandro |title=Perspectives in Animal Phylogeny and Evolution |url={{GBurl|id=jIASDAAAQBAJ|p=53}} |year=2009 |publisher=[[Oxford University Press]] |isbn=978-0-19-856620-5 |page=53}}</ref><ref name=Brusca2016>{{Cite book |url=https://www.sinauer.com/media/wysiwyg/samples/Brusca3e_Chapter_9.pdf |chapter=Introduction to the Bilateria and the Phylum Xenacoelomorpha {{!}} Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation |title=Invertebrates |last=Brusca |first=Richard C. |date=2016 |publisher=[[Sinauer Associates]] |pages=345–372 |isbn=978-1-60535-375-3 |access-date=4 March 2018 |archive-url=https://web.archive.org/web/20190424155137/https://www.sinauer.com/media/wysiwyg/samples/Brusca3e_Chapter_9.pdf |archive-date=24 April 2019 |url-status=live }}</ref>

Genetic studies have considerably changed zoologists' understanding of the relationships within the Bilateria. Most appear to belong to two major lineages, the [[protostomes]] and the [[deuterostomes]].<ref name="Telford 2008 pp. 457–459">{{cite journal |last=Telford |first=Maximilian J. |title=Resolving Animal Phylogeny: A Sledgehammer for a Tough Nut? |journal=Developmental Cell |volume=14 |issue=4 |year=2008 |doi=10.1016/j.devcel.2008.03.016 |pages=457–459 |pmid=18410719|doi-access=free }}</ref> It is often suggested that the basalmost bilaterians are the [[Xenacoelomorpha]], with all other bilaterians belonging to the subclade [[Nephrozoa]].<ref name="Philippe2011">{{cite journal |last1=Philippe |first1=H. |last2=Brinkmann |first2=H. |last3=Copley |first3=R.R. |last4=Moroz |first4=L. L. |last5=Nakano |first5=H. |last6=Poustka |first6=A.J. |last7=Wallberg |first7=A. |last8=Peterson |first8=K. J. |last9=Telford |first9=M.J. |title=Acoelomorph flatworms are deuterostomes related to ''Xenoturbella'' |journal=[[Nature (journal)|Nature]] |volume=470 |pages=255–258 |year=2011 |pmid=21307940 |doi=10.1038/nature09676 |bibcode=2011Natur.470..255P |issue=7333 |pmc=4025995}}</ref><ref name="Perseke2007">{{cite journal |last1=Perseke |first1=M. |last2=Hankeln |first2=T. |last3=Weich |first3=B. |last4=Fritzsch |first4=G. |last5=Stadler |first5=P.F. |last6=Israelsson |first6=O. |last7=Bernhard |first7=D. |last8=Schlegel |first8=M. |title=The mitochondrial DNA of Xenoturbella bocki: genomic architecture and phylogenetic analysis |journal=Theory Biosci |volume=126 |issue=1 |date=August 2007 |pages=35–42 |url=https://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf |pmid=18087755 |doi=10.1007/s12064-007-0007-7 |citeseerx=10.1.1.177.8060 |s2cid=17065867 |access-date=4 March 2018 |archive-url=https://web.archive.org/web/20190424154927/https://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf |archive-date=24 April 2019 |url-status=live }}</ref><ref name="Cannon 2016">{{cite journal |last1=Cannon |first1=Johanna T. |last2=Vellutini |first2=Bruno C. |last3=Smith III |first3=Julian. |last4=Ronquist |first4=Frederik |last5=Jondelius |first5=Ulf |last6=Hejnol |first6=Andreas |date=3 February 2016 |title=Xenacoelomorpha is the sister group to Nephrozoa |journal=[[Nature (journal)|Nature]] |volume=530 |issue=7588 |pages=89–93 |doi=10.1038/nature16520 |pmid=26842059 |bibcode=2016Natur.530...89C |s2cid=205247296 |url=https://urn.kb.se/resolve?urn=urn:nbn:se:nrm:diva-1844 |access-date=21 February 2022 |archive-date=30 July 2022 |archive-url=https://web.archive.org/web/20220730091447/http://nrm.diva-portal.org/smash/record.jsf?pid=diva2%3A1037430&dswid=-7165 |url-status=live }}</ref> However, this suggestion has been contested, with other studies finding that xenacoelomorphs are more closely related to Ambulacraria than to other bilaterians.<ref name="Kapli 2021" />
{{clear}}

==== Protostomes and deuterostomes ====

{{further|Embryological origins of the mouth and anus}}

{{main|Protostome|Deuterostome}}

[[File:Protovsdeuterostomes.svg|thumb|The bilaterian gut develops in two ways. In many [[protostome]]s, the blastopore develops into the mouth, while in [[deuterostome]]s it becomes the anus.]]

Protostomes and deuterostomes differ in several ways. Early in development, deuterostome embryos undergo radial [[Cleavage (embryo)|cleavage]] during cell division, while many protostomes (the [[Spiralia]]) undergo spiral cleavage.<ref>{{cite journal |last=Valentine |first=James W. |date=July 1997 |title=Cleavage patterns and the topology of the metazoan tree of life |journal=PNAS |volume=94 |pages=8001–8005 |bibcode=1997PNAS...94.8001V |doi=10.1073/pnas.94.15.8001 |pmid=9223303 |pmc=21545 |issue=15|doi-access=free }}</ref>
Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the [[archenteron|embryonic gut]] develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily.<ref>{{cite book |last1=Peters |first1=Kenneth E. |last2=Walters |first2=Clifford C. |last3=Moldowan |first3=J. Michael |title=The Biomarker Guide: Biomarkers and isotopes in petroleum systems and Earth history |volume=2 |year=2005 |publisher=Cambridge University Press |isbn=978-0-521-83762-0 |page=717}}</ref><ref name=Hejnol2009>{{cite book |last1=Hejnol |first1=A. |last2=Martindale |first2=M.Q. |url=https://www.researchgate.net/publication/230766195 |chapter=The mouth, the anus, and the blastopore – open questions about questionable openings |title=Animal Evolution – Genomes, Fossils, and Trees |editor1=Telford, M.J. |editor2=Littlewood, D.J. |date=2009 |publisher=Oxford University Press |isbn=978-0-19-957030-0 |pages=33–40 |access-date=1 March 2018 |archive-url=https://web.archive.org/web/20181028190247/https://www.researchgate.net/publication/230766195 |archive-date=28 October 2018 |url-status=live }}</ref> Most protostomes have [[Schizocoely|schizocoelous development]], where cells simply fill in the interior of the gastrula to form the mesoderm. In deuterostomes, the mesoderm forms by [[Enterocoely|enterocoelic pouching]], through invagination of the endoderm.<ref>{{cite book |last=Safra |first=Jacob E. |title=The New Encyclopædia Britannica, Volume 1; Volume 3 |year=2003 |publisher=Encyclopædia Britannica |isbn=978-0-85229-961-6 |page=767}}</ref>

The main deuterostome phyla are the Echinodermata and the Chordata.<ref>{{cite book |last=Hyde |first=Kenneth |title=Zoology: An Inside View of Animals |year=2004 |publisher=[[Kendall Hunt]] |isbn=978-0-7575-0997-1 |page=345}}</ref> Echinoderms are exclusively marine and include [[starfish]], [[sea urchin]]s, and [[sea cucumber]]s.<ref>{{cite book |last=Alcamo |first=Edward |title=Biology Coloring Workbook |year=1998 |publisher=[[The Princeton Review]] |isbn=978-0-679-77884-4 |page=220}}</ref> The chordates are dominated by the [[vertebrates]] (animals with [[Vertebral column|backbones]]),<ref>{{cite book |last=Holmes |first=Thom |title=The First Vertebrates |publisher=Infobase Publishing |year=2008 |isbn=978-0-8160-5958-4 |page=64}}</ref> which consist of [[fish]]es, [[amphibia]]ns, [[reptile]]s, [[bird]]s, and [[mammal<!--1st usage in main text-->]]s.<ref>{{cite book |last=Rice |first=Stanley A. |title=Encyclopedia of evolution |publisher=Infobase Publishing |year=2007 |page=[https://archive.org/details/encyclopediaofev0000rice/page/75 75] |isbn=978-0-8160-5515-9 |url=https://archive.org/details/encyclopediaofev0000rice/page/75 }}</ref> The deuterostomes also include the [[Hemichordata]] (acorn worms).<ref>{{cite book |last1=Tobin |first1=Allan J. |last2=Dusheck |first2=Jennie |title=Asking about life |year=2005 |publisher=Cengage Learning |isbn=978-0-534-40653-0 |page=497}}</ref><ref>{{cite journal |title=Hemichordate genomes and deuterostome origins |journal=[[Nature (journal)|Nature]] |date=26 November 2015 |pages=459–465 |volume=527 |issue=7579 |doi=10.1038/nature16150 |first1=Oleg |last1=Simakov |first2=Takeshi |last2=Kawashima |first3=Ferdinand |last3=Marlétaz |first4=Jerry |last4=Jenkins |first5=Ryo |last5=Koyanagi |first6=Therese |last6=Mitros |first7=Kanako |last7=Hisata |first8=Jessen |last8=Bredeson |first9=Eiichi |last9=Shoguchi |pmid=26580012 |pmc=4729200 |bibcode=2015Natur.527..459S }}</ref>

===== Ecdysozoa =====

{{main|Ecdysozoa}}

[[File:Anax Imperator 2(loz).JPG|thumb|left|upright|[[Ecdysis]]: a [[dragonfly]] has emerged from its dry [[exuviae]] and is expanding its wings. Like other [[arthropods]], its body is [[Segmentation (biology)|divided into segments]].]]

The Ecdysozoa are protostomes, named after their shared [[Phenotypic trait|trait]] of [[ecdysis]], growth by moulting.<ref>{{cite book |last=Dawkins |first=Richard |author-link=Richard Dawkins |title=The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution |year=2005 |publisher=[[Houghton Mifflin Harcourt]] |isbn=978-0-618-61916-0 |page=[https://archive.org/details/ancestorstale00rich_0/page/381 381] |url=https://archive.org/details/ancestorstale00rich_0/page/381 }}</ref> They include the largest animal phylum, the [[Arthropod]]a, which contains insects, spiders, crabs, and their kin. All of these have a body divided into [[Segmentation (biology)|repeating segments]], typically with paired appendages. Two smaller phyla, the [[Onychophora]] and [[Tardigrada]], are close relatives of the arthropods and share these traits. The ecdysozoans also include the Nematoda or roundworms, perhaps the second largest animal phylum. Roundworms are typically microscopic and occur in nearly every environment where there is water;<ref>{{cite book |last1=Prewitt |first1=Nancy L. |last2=Underwood |first2=Larry S. |last3=Surver |first3=William |title=BioInquiry: making connections in biology |year=2003 |publisher=John Wiley |isbn=978-0-471-20228-8 |page=[https://archive.org/details/bioinquiry00nanc_0/page/289 289] |url=https://archive.org/details/bioinquiry00nanc_0/page/289 }}</ref> some are important parasites.<ref>{{cite book |title=Parasites in social insects |year=1998 |publisher=[[Princeton University Press]] |isbn=978-0-691-05924-2 |last=Schmid-Hempel |first=Paul |page=75}}</ref> Smaller phyla related to them are the [[Nematomorpha]] or horsehair worms, and the [[Kinorhyncha]], [[Priapulida]], and [[Loricifera]]. These groups have a reduced coelom, called a pseudocoelom.<ref>{{cite book |last1=Miller |first1=Stephen A. |last2=Harley |first2=John P. |title=Zoology |url={{GBurl|id=BWZFAQAAIAAJ}} |year=2006 |publisher=[[McGraw-Hill]] |page=173 |isbn=978-0-07-063682-8}}</ref>

===== Spiralia =====

{{main|Spiralia}}

[[File:Spiral cleavage in Trochus.png|thumb|upright=1.5|[[Spiral cleavage]] in a sea snail embryo]]

The Spiralia are a large group of protostomes that develop by spiral cleavage in the early embryo.<ref name=Shankland>{{cite journal |pmid=10781038 |pmc=34316 |jstor=122407 |bibcode=2000PNAS...97.4434S |doi=10.1073/pnas.97.9.4434 |title=Evolution of the bilaterian body plan: What have we learned from annelids? |journal=Proceedings of the National Academy of Sciences |volume=97 |issue=9 |pages=4434–4437 |year=2000|last1=Shankland |first1=M. |last2=Seaver |first2=E.C. |doi-access=free }}</ref> The Spiralia's phylogeny has been disputed, but it contains a large clade, the superphylum [[Lophotrochozoa]], and smaller groups of phyla such as the [[Rouphozoa]] which includes the [[gastrotrich]]s and the [[flatworm]]s. All of these are grouped as the [[Platytrochozoa]], which has a sister group, the [[Gnathifera (clade)|Gnathifera]], which includes the [[rotifer]]s.<ref name=Struck2014>{{cite journal |last1=Struck |first1=Torsten H. |last2=Wey-Fabrizius |first2=Alexandra R. |last3=Golombek |first3=Anja |last4=Hering |first4=Lars |last5=Weigert |first5=Anne |last6=Bleidorn |first6=Christoph |last7=Klebow |first7=Sabrina |last8=Iakovenko |first8=Nataliia |last9=Hausdorf |first9=Bernhard |last10=Petersen |first10=Malte |last11=Kück |first11=Patrick |last12=Herlyn |first12=Holger |last13=Hankeln |first13=Thomas |title=Platyzoan Paraphyly Based on Phylogenomic Data Supports a Noncoelomate Ancestry of Spiralia |journal=Molecular Biology and Evolution |volume=31 |issue=7 |date=2014 |doi=10.1093/molbev/msu143 |pages=1833–1849 |pmid=24748651|doi-access=free }}</ref><ref>{{Cite journal |last1=Fröbius |first1=Andreas C. |last2=Funch |first2=Peter |date=April 2017 |title=Rotiferan Hox genes give new insights into the evolution of metazoan bodyplans |journal=Nature Communications |volume=8 |issue=1 |pages=9 |doi=10.1038/s41467-017-00020-w |pmid=28377584 |pmc=5431905 |bibcode=2017NatCo...8....9F }}</ref>

The Lophotrochozoa includes the [[mollusc]]s, [[annelid]]s, [[brachiopod]]s, [[nemertea]]ns, [[bryozoa]] and [[Entoprocta|entoprocts]].<ref name=Struck2014/><ref>{{cite journal|last1=Hervé |first1=Philippe |last2=Lartillot |first2=Nicolas |last3=Brinkmann |first3=Henner |date=May 2005 |title=Multigene Analyses of Bilaterian Animals Corroborate the Monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia |journal=Molecular Biology and Evolution |volume=22 |issue=5|pages=1246–1253 |doi=10.1093/molbev/msi111 |pmid=15703236|doi-access=free }}</ref><ref>{{cite web |title=Introduction to the Lophotrochozoa {{!}} Of molluscs, worms, and lophophores... |url=https://www.ucmp.berkeley.edu/phyla/lophotrochozoa.html |publisher=UCMP Berkeley |access-date=28 February 2018 |archive-url=https://web.archive.org/web/20000816183847/https://www.ucmp.berkeley.edu/phyla/lophotrochozoa.html |archive-date=16 August 2000 |url-status=dead |last=Speer |first=Brian R. |date=2000 }}</ref> The molluscs, the second-largest animal phylum by number of described species, includes [[snail]]s, [[clam]]s, and [[squid]]s, while the annelids are the segmented worms, such as [[earthworm]]s, [[lugworm]]s, and [[leech]]es. These two groups have long been considered close relatives because they share [[trochophore]] larvae.<ref name=Giribet2000>{{cite journal |last1=Giribet |first1=G. |last2=Distel |first2=D.L. |last3=Polz |first3=M. |last4=Sterrer |first4=W. |last5=Wheeler |first5=W.C. |year=2000 |title=Triploblastic relationships with emphasis on the acoelomates and the position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: a combined approach of 18S rDNA sequences and morphology |journal=Syst Biol |volume=49 |issue=3 |pages=539–562 |doi=10.1080/10635159950127385 |pmid=12116426|doi-access=free }}</ref><ref>{{cite journal |title=Phylogenetic Relationships of Annelids, Molluscs, and Arthropods Evidenced from Molecules and Morphology |journal=[[Journal of Molecular Evolution]] |volume=43 |issue=3 |pages=207–215 |date=September 1996 |doi=10.1007/PL00006079 |pmid=8703086 |last1=Kim |first1=Chang Bae |last2=Moon |first2=Seung Yeo |last3=Gelder |first3=Stuart R. |last4=Kim |first4=Won|bibcode=1996JMolE..43..207K }}</ref>

== History of classification ==

{{further|Taxonomy (biology)|History of zoology through 1859|History of zoology since 1859}}

[[File:Jean-Baptiste de Lamarck.jpg|thumb|left|upright|[[Jean-Baptiste de Lamarck]] led the creation of a modern classification of [[invertebrates]], breaking up Linnaeus's "Vermes" into 9 phyla by 1809.<ref name=Gould2011/>]]

In the [[classical era]], Aristotle [[Aristotle's biology|divided animals]],{{efn|In his ''[[History of Animals]]'' and ''[[Parts of Animals]]''.}} based on his own observations, into those with blood (roughly, the vertebrates) and those without. The animals were then [[Scala naturae|arranged on a scale]] from man (with blood, 2 legs, rational soul) down through the live-bearing tetrapods (with blood, 4 legs, sensitive soul) and other groups such as crustaceans (no blood, many legs, sensitive soul) down to spontaneously generating creatures like sponges (no blood, no legs, vegetable soul). [[Aristotle]] was uncertain whether sponges were animals, which in his system ought to have sensation, appetite, and locomotion, or plants, which did not: he knew that sponges could sense touch and would contract if about to be pulled off their rocks, but that they were rooted like plants and never moved about.<ref>{{cite book |last=Leroi |first=Armand Marie |author-link=Armand Marie Leroi |title=The Lagoon: How Aristotle Invented Science |title-link=Aristotle's Lagoon |publisher=Bloomsbury |date=2014 |isbn=978-1-4088-3622-4 |pages=111–119, 270–271}}</ref>

In 1758, [[Carl Linnaeus<!--1st usage in main text-->]] created the first [[hierarchical]] classification in his ''[[Systema Naturae]]''.<ref name=Linn1758>{{cite book |last=Linnaeus |first=Carl |author-link=Carl Linnaeus |title=Systema naturae per regna tria naturae :secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. |edition=[[10th edition of Systema Naturae|10th]] |publisher=Holmiae (Laurentii Salvii) |year=1758 |url=https://www.biodiversitylibrary.org/bibliography/542 |access-date=22 September 2008 |language=la |trans-title=The System of Nature through the Three Kingdoms of Nature |archive-url=https://web.archive.org/web/20081010032456/https://www.biodiversitylibrary.org/bibliography/542 |archive-date=10 October 2008 |url-status=live}}</ref> In his original scheme, the animals were one of three kingdoms, divided into the classes of [[Vermes in the 10th edition of Systema Naturae|Vermes]], [[Insecta in the 10th edition of Systema Naturae|Insecta]], [[Pisces in the 10th edition of Systema Naturae|Pisces]], [[Amphibia in the 10th edition of Systema Naturae|Amphibia]], [[Aves in the 10th edition of Systema Naturae|Aves]], and [[Mammalia in the 10th edition of Systema Naturae|Mammalia]]. Since then, the last four have all been subsumed into a single phylum, the [[chordate|Chordata]], while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by [[Jean-Baptiste de Lamarck<!--1st usage in main text-->]], who called the Vermes ''une espèce de chaos'' (a chaotic mess){{efn|The French prefix ''une espèce de'' is pejorative.<ref>{{cite web |title=Espèce de |url=https://dictionnaire.reverso.net/francais-anglais/esp%C3%A8ce%20de%20cr%C3%A9tin |publisher=Reverso Dictionnnaire |access-date=1 March 2018 |archive-url=https://web.archive.org/web/20130728151210/https://dictionnaire.reverso.net/francais-anglais/esp%C3%A8ce%20de%20cr%C3%A9tin |archive-date=28 July 2013 |url-status=live }}</ref>}} and split the group into three new phyla: worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his ''[[Philosophie Zoologique]]'', Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely [[cirripede]]s, annelids, crustaceans, arachnids, insects, worms, [[Radiata|radiates]], polyps, and [[infusoria]]ns.<ref name=Gould2011>{{cite book |last=Gould |first=Stephen Jay |author-link=Stephen Jay Gould |title=The Lying Stones of Marrakech |url={{GBurl|id=wApMpVmi-5gC|p=130}} |year=2011 |publisher=Harvard University Press |isbn=978-0-674-06167-5 |pages=130–134}}</ref>

In his 1817 ''[[Le Règne Animal]]'', [[Georges Cuvier<!--1st usage in main text-->]] used [[comparative anatomy]] to group the animals into four ''embranchements'' ("branches" with different body plans, roughly corresponding to phyla), namely vertebrates, molluscs, articulated animals (arthropods and annelids), and [[zoophytes|zoophytes (radiata)]] (echinoderms, cnidaria and other forms).<ref>{{cite book |last=De Wit |first=Hendrik C. D. |title=Histoire du Développement de la Biologie, Volume III |publisher=Presses Polytechniques et Universitaires Romandes |date=1994 |pages=94–96 |isbn=978-2-88074-264-5}}</ref> This division into four was followed by the embryologist [[Karl Ernst von Baer]] in 1828, the zoologist [[Louis Agassiz]] in 1857, and the comparative anatomist [[Richard Owen]] in 1860.<ref name=Valentine2004/>

In 1874, [[Ernst Haeckel<!--1st usage in main text-->]] divided the animal kingdom into two subkingdoms: Metazoa (multicellular animals, with five phyla: coelenterates, echinoderms, articulates, molluscs, and vertebrates) and Protozoa (single-celled animals), including a sixth animal phylum, sponges.<ref>{{cite book |last1=Haeckel |first1=Ernst |author-link=Ernst Haeckel |title=Anthropogenie oder Entwickelungsgeschichte des menschen |url=https://archive.org/details/anthropogenieod05haecgoog |year=1874 |page=202 |language=de |trans-title=Anthropogeny or the Development story of Humans |publisher=W. Engelmann }}</ref><ref name=Valentine2004>{{cite book |last=Valentine |first=James W. |title=On the Origin of Phyla |url={{GBurl|id=DMBkmHm5fe4C|p=8}} |year=2004 |publisher=University of Chicago Press |isbn=978-0-226-84548-7 |pages=7–8}}</ref> The protozoa were later moved to the former kingdom [[Protista]], leaving only the Metazoa as a synonym of Animalia.<ref>{{cite book |last1=Hutchins |first1=Michael |title=Grzimek's Animal Life Encyclopedia |url=https://archive.org/details/animallifeprotos02mich_714 |url-access=limited |year=2003 |edition=2nd |publisher=Gale |isbn=978-0-7876-5777-2 |page=[https://archive.org/details/animallifeprotos02mich_714/page/n21 3]}}</ref>

== In human culture ==

=== Practical uses ===

{{main|Animals in culture}}

[[File:Carni bovine macellate.JPG|thumb|upright|left|Sides of [[beef]] in a [[slaughterhouse]]]]

The human population exploits a large number of other animal species for food, both of [[domestication of animals|domesticated]] livestock species in [[animal husbandry]] and, mainly at sea, by hunting wild species.<ref name=FAOFish>{{cite web |url=https://www.fao.org/fishery/ |title=Fisheries and Aquaculture |publisher=[[Food and Agriculture Organization]] |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20090519173740/https://www.fao.org/fishery |archive-date=19 May 2009 |url-status=live }}</ref><ref name=Economist/> Marine fish of many species are [[fishing|caught commercially]] for food. A smaller number of species are [[fish farming|farmed commercially]].<ref name=FAOFish/><ref>{{cite book |last=Helfman |first=Gene S. |title=Fish Conservation: A Guide to Understanding and Restoring Global Aquatic Biodiversity and Fishery Resources |url=https://archive.org/details/fishconservation00helf |url-access=limited |date=2007 |publisher=Island Press |isbn=978-1-59726-760-1 |page=[https://archive.org/details/fishconservation00helf/page/n25 11]}}</ref><ref>{{cite web |title=World Review of Fisheries and Aquaculture |url=https://www.fao.org/docrep/016/i2727e/i2727e01.pdf |publisher=FAO |access-date=13 August 2015 |archive-url=https://web.archive.org/web/20150828131307/https://www.fao.org/docrep/016/i2727e/i2727e01.pdf |archive-date=28 August 2015 |url-status=live }}</ref> Humans and their [[livestock]] make up more than 90% of the biomass of all terrestrial vertebrates, and almost as much as all insects combined.<ref name="Eggleton 2020">{{cite journal |last=Eggleton |first=Paul |title=The State of the World's Insects |journal=Annual Review of Environment and Resources |date=17 October 2020 |volume=45 |issue=1 |pages=61–82 |doi=10.1146/annurev-environ-012420-050035 |doi-access=free}}</ref>

[[Invertebrates]] including [[cephalopod]]s, [[crustacea]]ns, and [[bivalve]] or [[gastropod]] molluscs are hunted or farmed for food.<ref>{{cite journal |title=Shellfish climbs up the popularity ladder |journal=Seafood Business |url=https://www.highbeam.com/doc/1G1-85675992.html |archive-url=https://web.archive.org/web/20121105143157/https://www.highbeam.com/doc/1G1-85675992.html |url-status=dead |archive-date=5 November 2012 |access-date=8 July 2016 |date=January 2002 }}</ref> [[Chicken]]s, [[cattle]], [[sheep]], [[pig]]s, and other animals are raised as livestock for meat across the world.<ref name=Economist>{{cite news |title=Graphic detail Charts, maps and infographics. Counting chickens |newspaper=The Economist |url=https://www.economist.com/blogs/dailychart/2011/07/global-livestock-counts |access-date=23 June 2016 |date=27 July 2011 |archive-url=https://web.archive.org/web/20160715181213/https://www.economist.com/blogs/dailychart/2011/07/global-livestock-counts |archive-date=15 July 2016 |url-status=live }}</ref><ref>{{cite web |url=https://cattle-today.com/ |title=Breeds of Cattle at Cattle Today |publisher=Cattle-today.com |access-date=15 October 2013 |archive-url=https://web.archive.org/web/20110715234745/https://cattle-today.com/ |archive-date=15 July 2011 |url-status=live }}</ref><ref>{{cite web |last1=Lukefahr |first1=S. D. |last2=Cheeke |first2=P. R. |title=Rabbit project development strategies in subsistence farming systems |url=https://www.fao.org/docrep/U4900T/u4900T0m.htm |publisher=[[Food and Agriculture Organization]] |access-date=23 June 2016 |archive-url=https://web.archive.org/web/20160506105314/https://www.fao.org/docrep/U4900T/u4900T0m.htm |archive-date=6 May 2016 |url-status=live }}</ref> Animal fibres such as wool are used to make textiles, while animal [[sinew]]s have been used as lashings and bindings, and leather is widely used to make shoes and other items. Animals have been hunted and farmed for their fur to make items such as coats and hats.<ref>{{cite web |title=Ancient fabrics, high-tech geotextiles |url=https://www.naturalfibres2009.org/en/fibres/ |publisher=Natural Fibres |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160720093749/https://www.naturalfibres2009.org/en/fibres/ |archive-date=20 July 2016 |url-status=dead }}</ref> Dyestuffs including [[carmine]] ([[cochineal]]),<ref>{{cite book |url=https://www.fao.org/docrep/v8879e/v8879e09.htm |chapter=Cochineal and Carmine |title=Major colourants and dyestuffs, mainly produced in horticultural systems |publisher=FAO |access-date=16 June 2015 |archive-url=https://web.archive.org/web/20180306060330/https://www.fao.org/docrep/v8879e/V8879e09.htm |archive-date=6 March 2018 |url-status=live }}</ref><ref>{{cite web |url=https://www.fda.gov/ForIndustry/ColorAdditives/GuidanceComplianceRegulatoryInformation/ucm153038.htm |title=Guidance for Industry: Cochineal Extract and Carmine |publisher=FDA |access-date=6 July 2016 |archive-url=https://web.archive.org/web/20160713100106/https://www.fda.gov/ForIndustry/ColorAdditives/GuidanceComplianceRegulatoryInformation/ucm153038.htm |archive-date=13 July 2016 |url-status=live }}</ref> [[shellac]],<ref>{{cite news |title=How Shellac Is Manufactured |url=https://nla.gov.au/nla.news-article55073762 |access-date=17 July 2015 |newspaper=The Mail (Adelaide, SA : 1912–1954) |date=18 December 1937 |archive-date=30 July 2022 |archive-url=https://web.archive.org/web/20220730091433/https://trove.nla.gov.au/newspaper/article/55073762 |url-status=live }}</ref><ref>{{cite journal |last1=Pearnchob |first1=N. |last2=Siepmann |first2=J. |author3=Bodmeier, R. |year=2003 |title=Pharmaceutical applications of shellac: moisture-protective and taste-masking coatings and extended-release matrix tablets |journal=Drug Development and Industrial Pharmacy |volume=29 |issue=8 |pages=925–938 |pmid=14570313 |doi=10.1081/ddc-120024188|s2cid=13150932 }}</ref> and [[Kermes (dye)|kermes]]<ref>{{cite book |last=Barber |first=E. J. W. |title=Prehistoric Textiles |year=1991 |publisher=Princeton University Press |isbn=978-0-691-00224-8 |pages=230–231}}</ref><ref name="Munro214">{{cite book |last=Munro |first=John H. |title=The Cambridge History of Western Textiles |chapter=Medieval Woollens: Textiles, Technology, and Organisation |editor-last1=Jenkins |editor-first1=David |year=2003 |publisher=Cambridge University Press |isbn=978-0-521-34107-3 |pages=214–215}}</ref> have been made from the bodies of insects. [[Working animals]] including cattle and horses have been used for work and transport from the first days of agriculture.<ref name="Pond2004">{{cite book |last=Pond |first=Wilson G. |title=Encyclopedia of Animal Science |url={{GBurl|id=1SQl7Ao3mHoC|p=248}} |year=2004 |publisher=CRC Press |isbn=978-0-8247-5496-9 |pages=248–250 |access-date=22 February 2018 }}</ref>

Animals such as the fruit fly ''[[Drosophila melanogaster]]'' serve a major role in science as [[model organism|experimental models]].<ref>{{cite web |title=Genetics Research |url=https://www.aht.org.uk/cms-display/genetics.html |publisher=Animal Health Trust |access-date=24 June 2016 |archive-url=https://web.archive.org/web/20171212193051/https://www.aht.org.uk/cms-display/genetics.html |archive-date=12 December 2017 |url-status=dead }}</ref><ref>{{cite web |title=Drug Development |url=https://www.animalresearch.info/en/drug-development/ |publisher=Animal Research.info |access-date=24 June 2016 |archive-url=https://web.archive.org/web/20160608124406/https://www.animalresearch.info/en/drug-development/ |archive-date=8 June 2016 |url-status=live }}</ref><ref>{{cite web |title=Animal Experimentation |url=https://www.bbc.co.uk/ethics/animals/using/experiments_1.shtml |publisher=BBC |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160701220536/https://www.bbc.co.uk/ethics/animals/using/experiments_1.shtml |archive-date=1 July 2016 |url-status=live }}</ref><ref name="EUstatistics2013">{{cite web |title=EU statistics show decline in animal research numbers |url=https://speakingofresearch.com/2013/12/12/eu-statistics-show-decline-in-animal-research-numbers/ |publisher=Speaking of Research |year=2013 |access-date=24 January 2016 |archive-url=https://web.archive.org/web/20171006162448/https://speakingofresearch.com/2013/12/12/eu-statistics-show-decline-in-animal-research-numbers/ |archive-date=6 October 2017 |url-status=live }}</ref> Animals have been used to create [[vaccine]]s since their discovery in the 18th century.<ref>{{cite web |title=Vaccines and animal cell technology |date=10 June 2013 |url=https://www.actip.org/library/vaccines-and-animal-cell-technology/ |publisher=Animal Cell Technology Industrial Platform |access-date=9 July 2016 |archive-url=https://web.archive.org/web/20160713184805/https://www.actip.org/library/vaccines-and-animal-cell-technology/ |archive-date=13 July 2016 |url-status=live }}</ref> Some medicines such as the cancer drug [[trabectedin]] are based on [[toxin]]s or other molecules of animal origin.<ref>{{cite web |title=Medicines by Design |url=https://publications.nigms.nih.gov/medbydesign/chapter3.html |publisher=National Institute of Health |access-date=9 July 2016 |archive-url=https://web.archive.org/web/20160604214644/https://publications.nigms.nih.gov/medbydesign/chapter3.html |archive-date=4 June 2016 |url-status=live }}</ref>

[[File:Hebbuz.JPG|thumb|A [[gun dog]] retrieving a duck during a hunt]]

People have used [[hunting dog]]s to help chase down and retrieve animals,<ref>{{cite book |last=Fergus |first=Charles |title=Gun Dog Breeds, A Guide to Spaniels, Retrievers, and Pointing Dogs |publisher=The Lyons Press |date=2002 |isbn=978-1-58574-618-7}}</ref> and [[Bird of prey|birds of prey]] to catch birds and mammals,<ref>{{cite web |title=History of Falconry |url=https://www.thefalconrycentre.co.uk/bird-info/conservation/nocturnal-raptors/history-falconry/ |publisher=The Falconry Centre |access-date=22 April 2016 |archive-url=https://web.archive.org/web/20160529023926/https://thefalconrycentre.co.uk/bird-info/conservation/nocturnal-raptors/history-falconry/ |archive-date=29 May 2016 |url-status=live }}</ref> while tethered [[cormorant]]s have been [[Cormorant fishing|used to catch fish]].<ref name="King2013">{{cite book |last=King |first=Richard J. |title=The Devil's Cormorant: A Natural History |url={{GBurl|id=ucGyAAAAQBAJ|p=9}} |date=2013 |publisher=University of New Hampshire Press |isbn=978-1-61168-225-0 |page=9}}</ref> [[Poison dart frog]]s have been used to poison the tips of [[blowdart|blowpipe darts]].<ref name="amphibiaweb1">{{cite web |url=https://amphibiaweb.org/lists/Dendrobatidae.shtml |title=AmphibiaWeb – Dendrobatidae |publisher=AmphibiaWeb |access-date=10 October 2008 |archive-url=https://web.archive.org/web/20110810090554/https://amphibiaweb.org/lists/Dendrobatidae.shtml |archive-date=10 August 2011 |url-status=live }}</ref><ref>{{cite web |url=https://animaldiversity.ummz.umich.edu/site/accounts/information/Dendrobatidae.html |title=Dendrobatidae |access-date=9 July 2016 |last=Heying |first=H. |year=2003 |publisher=Animal Diversity Web |archive-url=https://web.archive.org/web/20110212005358/https://animaldiversity.ummz.umich.edu/site/accounts/information/Dendrobatidae.html |archive-date=12 February 2011 |url-status=live }}</ref>
A wide variety of animals are kept as pets, from invertebrates such as tarantulas, octopuses, and [[praying mantis]]es,<ref>{{cite web |title=Other bugs |date=18 February 2011 |url=https://www.keepinginsects.com/cockroaches-locusts-ants/ |publisher=Keeping Insects |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160707170022/https://www.keepinginsects.com/cockroaches-locusts-ants/ |archive-date=7 July 2016 |url-status=live }}</ref> reptiles such as [[snake]]s and [[chameleon]]s,<ref>{{cite web |last=Kaplan |first=Melissa |title=So, you think you want a reptile? |url=https://www.anapsid.org/parent.html |publisher=Anapsid.org |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160703115141/https://www.anapsid.org/parent.html |archive-date=3 July 2016 |url-status=live }}</ref> and birds including [[Domestic canary|canaries]], [[parakeet]]s, and [[parrot]]s<ref>{{cite web |title=Pet Birds |url=https://www.humanesociety.org/animals/pet_birds/ |publisher=PDSA |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160707053516/https://www.humanesociety.org/animals/pet_birds/ |archive-date=7 July 2016 |url-status=live }}</ref> all finding a place. However, the most kept pet species are mammals, namely [[dog]]s, [[cat]]s, and [[rabbit]]s.<ref>{{cite web |url=https://www.shea-online.org/Portals/0/PDFs/Animals%20in%20Healthcare%20Facilities.pdf |title=Animals in Healthcare Facilities |year=2012 |url-status=dead |archive-url=https://web.archive.org/web/20160304102728/https://www.shea-online.org/Portals/0/PDFs/Animals%20in%20Healthcare%20Facilities.pdf |archive-date=4 March 2016 }}</ref><ref>{{cite web |last=The Humane Society of the United States |title=U.S. Pet Ownership Statistics |url=https://www.humanesociety.org/issues/pet_overpopulation/facts/pet_ownership_statistics.html |access-date=27 April 2012 |archive-url=https://web.archive.org/web/20120407193941/https://www.humanesociety.org/issues/pet_overpopulation/facts/pet_ownership_statistics.html |archive-date=7 April 2012 |url-status=live }}</ref><ref>{{cite web |title=U.S. Rabbit Industry profile |publisher=[[United States Department of Agriculture]] |url=https://www.aphis.usda.gov/animal_health/emergingissues/downloads/RabbitReport1.pdf |access-date=10 July 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131020161216/https://www.aphis.usda.gov/animal_health/emergingissues/downloads/RabbitReport1.pdf |archive-date=20 October 2013 }}</ref> There is a tension between the role of animals as companions to humans, and their existence as [[animal rights|individuals with rights]] of their own.<ref>{{cite journal |last=Plous |first=S. |title=The Role of Animals in Human Society |date=1993 |doi=10.1111/j.1540-4560.1993.tb00906.x |journal=Journal of Social Issues |volume=49 |issue=1 |pages=1–9}}</ref>

A wide variety of terrestrial and aquatic animals are hunted [[Animals in sport|for sport]].<ref>{{cite book |last=Hummel |first=Richard |title=Hunting and Fishing for Sport: Commerce, Controversy, Popular Culture |date=1994 |publisher=Popular Press |isbn=978-0-87972-646-1 |url-access=registration |url=https://archive.org/details/huntingfishingfo0000humm }}</ref>

=== Symbolic uses ===

The [[signs of the zodiac|signs of the Western]] and [[Chinese zodiac]]s are based on animals.<ref>{{cite book |last=Lau |first=Theodora |title=The Handbook of Chinese Horoscopes |pages=2–8, 30–35, 60–64, 88–94, 118–124, 148–153, 178–184, 208–213, 238–244, 270–278, 306–312, 338–344 |publisher=Souvenir Press |year=2005}}</ref><ref name="Tester1987">{{cite book |last=Tester |first=S. Jim |title=A History of Western Astrology |url={{GBurl|id=L0HSvH96alIC|p=31}} |year=1987 |publisher=Boydell & Brewer |isbn=978-0-85115-446-6 |pages=31–33 and passim}}</ref> In China and Japan, the [[butterfly]] has been seen as the [[personification]] of a person's [[soul]],<ref name=Hearn>{{cite book |last=Hearn |first=Lafcadio |author-link=Lafcadio Hearn |year=1904 |title=Kwaidan: Stories and Studies of Strange Things |title-link=Kwaidan: Stories and Studies of Strange Things |publisher=Dover |isbn=978-0-486-21901-1}}</ref> and in classical representation the butterfly is also the symbol of the soul.<ref>{{Cite journal |url=https://quod.lib.umich.edu/cgi/t/text/text-idx?c=did;cc=did;rgn=main;view=text;idno=did2222.0001.694 |title=Butterfly |journal=Encyclopedia of Diderot and d'Alembert |access-date=16 December 2023 |date=January 2011 |first=Louis |last=De Jaucourt|archive-url=https://web.archive.org/web/20160811042437/https://quod.lib.umich.edu/cgi/t/text/text-idx?c=did;cc=did;rgn=main;view=text;idno=did2222.0001.694 |archive-date=11 August 2016 |url-status=live }}</ref><ref>Hutchins, M., Arthur V. Evans, Rosser W. Garrison and Neil Schlager (Eds) (2003), ''Grzimek's Animal Life Encyclopedia'', 2nd edition. Volume 3, Insects. Gale, 2003.</ref>

[[File:Alexander Coosemans - Still Life with Lobster and Oysters.jpg|thumb|Artistic vision: ''[[Still Life]] with [[Lobster]] and [[Oyster]]s'' by [[Alexander Coosemans]], {{Circa|1660}}]]

Animals have been the [[Animal style|subjects of art]] from the earliest times, both historical, as in ancient Egypt, and prehistoric, as in the [[Lascaux|cave paintings at Lascaux]]. Major animal paintings include [[Albrecht Dürer]]'s 1515 ''[[Dürer's Rhinoceros|The Rhinoceros]]'', and [[George Stubbs]]'s {{Circa|1762}} horse portrait ''[[Whistlejacket]]''.<ref name="Jones">{{cite news |last1=Jones |first1=Jonathan |title=The top 10 animal portraits in art |url=https://www.theguardian.com/artanddesign/jonathanjonesblog/2014/jun/27/top-10-animal-portraits-in-art |access-date=24 June 2016 |newspaper=[[The Guardian]] |date=27 June 2014 |archive-url=https://web.archive.org/web/20160518105922/https://www.theguardian.com/artanddesign/jonathanjonesblog/2014/jun/27/top-10-animal-portraits-in-art |archive-date=18 May 2016 |url-status=live }}</ref> [[Arthropods in film|Insects]], birds and mammals play roles in literature and film,<ref>{{Cite journal |last1=Paterson |first1=Jennifer |title=Animals in Film and Media |url=https://www.oxfordbibliographies.com/view/document/obo-9780199791286/obo-9780199791286-0044.xml |journal=Oxford Bibliographies |access-date=24 June 2016 |date=29 October 2013 |doi=10.1093/obo/9780199791286-0044 |archive-url=https://web.archive.org/web/20160614200642/https://www.oxfordbibliographies.com/view/document/obo-9780199791286/obo-9780199791286-0044.xml |archive-date=14 June 2016 |url-status=live }}</ref> such as in [[Big bug movie|giant bug movies]].<ref name="GregersdotterHöglund2016">{{cite book |last1=Gregersdotter |first1=Katarina |last2=Höglund |first2=Johan |last3=Hållén |first3=Nicklas |title=Animal Horror Cinema: Genre, History and Criticism |url={{GBurl|id=hV-hCwAAQBAJ|p=147}} |date=2016 |publisher=Springer |isbn=978-1-137-49639-3 |page=147}}</ref><ref name="WarrenThomas2009">{{cite book |last1=Warren |first1=Bill |last2=Thomas |first2=Bill |title=Keep Watching the Skies!: American Science Fiction Movies of the Fifties, The 21st Century Edition |url={{GBurl|id=B7kUCwAAQBAJ|pg=PT32}} |date=2009 |publisher=[[McFarland & Company]] |isbn=978-1-4766-2505-8 |page=32}}</ref><ref name="Crouse2008">{{cite book |last=Crouse |first=Richard |title=Son of the 100 Best Movies You've Never Seen |url={{GBurl|id=B5alnowvF3sC|pg=PT200}} |year=2008 |publisher=ECW Press |isbn=978-1-55490-330-6 |page=200}}</ref>

Animals including [[insects in mythology|insects]]<ref name=Hearn/> and mammals<ref name=TFL/> feature in mythology and religion. The [[Scarab (artifact)|scarab beetle]] was sacred in [[ancient Egypt]],<ref>{{cite book |last=Ben-Tor |first=Daphna |title=Scarabs, A Reflection of Ancient Egypt |location=Jerusalem |publisher=Israel Museum |date=1989 |isbn=978-965-278-083-6 |page=8}}</ref> and the [[Cattle in religion and mythology#Hinduism|cow is sacred in Hinduism]].<ref>{{Cite news |last=Biswas |first=Soutik |title=Why the humble cow is India's most polarising animal |url=https://www.bbc.co.uk/news/world-asia-india-34513185 |publisher=BBC |access-date=9 July 2016 |date=15 October 2015 |archive-url=https://web.archive.org/web/20161122205058/https://www.bbc.co.uk/news/world-asia-india-34513185 |archive-date=22 November 2016 |url-status=live }}</ref> Among other mammals, [[deer in mythology|deer]],<ref name=TFL>{{cite web |title=Deer |url=https://treesforlife.org.uk/forest/mythology-folklore/deer/ |publisher=[[Trees for Life (Scotland)|Trees for Life]] |access-date=23 June 2016 |archive-url=https://web.archive.org/web/20160614200842/https://treesforlife.org.uk/forest/mythology-folklore/deer/ |archive-date=14 June 2016 |url-status=live}}</ref> [[Horse worship|horses]],<ref>{{cite book |title=Hayagrīva: The Mantrayānic Aspect of Horse-cult in China and Japan |publisher=Brill Archive |page=9 |last=van Gulik |first=Robert Hans}}</ref> [[Cultural depictions of lions|lions]],<ref>{{cite web |last1=Grainger |first1=Richard |title=Lion Depiction across Ancient and Modern Religions |url=https://lionalert.org/page/Lion_Depiction_Across_Ancient_and_Modern_Religions |publisher=Alert |access-date=6 July 2016 |date=24 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20160923134807/https://lionalert.org/page/Lion_Depiction_Across_Ancient_and_Modern_Religions |archive-date=23 September 2016 }}</ref> [[Bat#Cultural significance|bats]],<ref name=ReadGonzalez>{{cite book |last1=Read |first1=Kay Almere |last2=Gonzalez |first2=Jason J. |year=2000 |title=Mesoamerican Mythology |publisher=[[Oxford University Press]] |pages=132–134}}</ref> [[bear worship|bears]],<ref>{{Cite journal |last=Wunn |first=Ina |s2cid=53595088 |date=January 2000 |title=Beginning of Religion |journal=Numen |volume=47 |issue=4 |pages=417–452 |doi=10.1163/156852700511612 }}</ref> and [[Wolves in folklore, religion and mythology|wolves]]<ref>{{cite book |last=McCone |first=Kim R. |chapter=Hund, Wolf, und Krieger bei den Indogermanen |editor=Meid, W. |title=Studien zum indogermanischen Wortschatz |location=Innsbruck |date=1987 |pages=101–154}}</ref> are the subjects of myths and worship.

== See also ==

* [[Animal coloration]]
* [[Ethology]]
* [[Lists of organisms by population]]
* [[World Animal Day]], observed on 4 October

== Notes ==
{{notelist}}

== References ==
{{reflist}}


== External links ==
==References==
* {{Commons category-inline}}
{{reflist|30em}}
* {{Wikispecies-inline}}
* [https://tolweb.org/ Tree of Life Project]. {{Webarchive|url=https://web.archive.org/web/20110612121424/http://www.tolweb.org//|date=12 June 2011}}
* [https://animaldiversity.org/ Animal Diversity Web] – [[University of Michigan]]'s database of animals
* [https://archive.today/20160426231847/https://www.arkive.org/ Wildscreen Arkive] – multimedia database of endangered/protected species


{{Maroon 5}}
{{Animalia}}
{{Eukaryota}}
{{Nature}}
{{Life on Earth}}
{{Organisms et al.}}


{{authority control}}
{{Taxonbar |from=Q729}}
{{Authority control}}


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[[Category:2014 singles]]
[[Category:Kingdoms (biology)|Animals]]
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Revision as of 22:17, 30 August 2024

Animals
Temporal range: Cryogenian – present, 665–0 Ma
EchinodermCnidariaTardigradeCrustaceanArachnidSpongeInsectBryozoaAcanthocephalaFlatwormMolluscaAnnelidVertebrateTunicatePhoronida
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Clade: Choanozoa
Kingdom: Animalia
Linnaeus, 1758
Subdivisions
Synonyms
  • Metazoa Haeckel 1874[1]
  • Choanoblastaea Nielsen 2008[2]
  • Gastrobionta Rothm. 1948[3]
  • Zooaea Barkley 1939[3]
  • Euanimalia Barkley 1939[3]

Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ˌænɪˈmliə/[4]). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor.

Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft). They have complex ecologies and interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology, and the study of animal behaviors is known as ethology.

Most living animal species belong to the infrakingdom Bilateria, a highly proliferative clade whose members have a bilaterally symmetric body plan. The vast majority belong to two large superphyla: the protostomes, which includes organisms such as the arthropods, molluscs, flatworms, annelids and nematodes; and the deuterostomes, which include the echinoderms, hemichordates and chordates, the latter of which contains the vertebrates. The simple Xenacoelomorpha have an uncertain position within Bilateria.

Animals first appear in the fossil record in the late Cryogenian period and diversified in the subsequent Ediacaran. Earlier evidence of animals is still controversial; the sponge-like organism Otavia has been dated back to the Tonian period at the start of the Neoproterozoic, but its identity as an animal is heavily contested.[5] Nearly all modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period.

Historically, Aristotle divided animals into those with blood and those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between taxa.

Humans make use of many other animal species for food (including meat, eggs, and dairy products), for materials (such as leather, fur, and wool), as pets and as working animals for transportation, and services. Dogs, the first domesticated animal, have been used in hunting, in security and in warfare, as have horses, pigeons and birds of prey; while other terrestrial and aquatic animals are hunted for sports, trophies or profits. Non-human animals are also an important cultural element of human evolution, having appeared in cave arts and totems since the earliest times, and are frequently featured in mythology, religion, arts, literature, heraldry, politics, and sports.

Etymology

The word animal comes from the Latin noun animal of the same meaning, which is itself derived from Latin animalis 'having breath or soul'.[6] The biological definition includes all members of the kingdom Animalia.[7] In colloquial usage, the term animal is often used to refer only to nonhuman animals.[8][9][10][11] The term metazoa is derived from Ancient Greek μετα (meta) 'after' (in biology, the prefix meta- stands for 'later') and ζῷᾰ (zōia) 'animals', plural of ζῷον zōion 'animal'.[12][13]

Characteristics

Animals are unique in having the ball of cells of the early embryo (1) develop into a hollow ball or blastula (2).

Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular.[14] Unlike plants and algae, which produce their own nutrients,[15] animals are heterotrophic,[16][17] feeding on organic material and digesting it internally.[18] With very few exceptions, animals respire aerobically.[a][20] All animals are motile[21] (able to spontaneously move their bodies) during at least part of their life cycle, but some animals, such as sponges, corals, mussels, and barnacles, later become sessile. The blastula is a stage in embryonic development that is unique to animals, allowing cells to be differentiated into specialised tissues and organs.[22]

Structure

All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins.[23] During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as shells, bones, and spicules.[24] In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth.[25] Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.[26]

With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues.[27] These include muscles, which enable locomotion, and nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal digestive chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians).[28]

Reproduction and development

Sexual reproduction is nearly universal in animals, such as these dragonflies.

Nearly all animals make use of some form of sexual reproduction.[29] They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova.[30] These fuse to form zygotes,[31] which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge.[32] In most other groups, the blastula undergoes more complicated rearrangement.[33] It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.[34] In most cases, a third germ layer, the mesoderm, also develops between them.[35] These germ layers then differentiate to form tissues and organs.[36]

Repeated instances of mating with a close relative during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits.[37][38] Animals have evolved numerous mechanisms for avoiding close inbreeding.[39]

Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids.[40][41]

Ecology

Predators, such as this ultramarine flycatcher (Ficedula superciliaris), feed on other animals.

Animals are categorised into ecological groups depending on their trophic levels and how they consume organic material. Such groupings include carnivores (further divided into subcategories such as piscivores, insectivores, ovivores, etc.), herbivores (subcategorized into folivores, graminivores, frugivores, granivores, nectarivores, algivores, etc.), omnivores, fungivores, scavengers/detritivores,[42] and parasites.[43] Interactions between animals of each biome form complex food webs within that ecosystem. In carnivorous or omnivorous species, predation is a consumer–resource interaction where the predator feeds on another organism, its prey,[44] who often evolves anti-predator adaptations to avoid being fed upon. Selective pressures imposed on one another lead to an evolutionary arms race between predator and prey, resulting in various antagonistic/competitive coevolutions.[45][46] Almost all multicellular predators are animals.[47] Some consumers use multiple methods; for example, in parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process,[48] but the adults primarily consume nectar from flowers.[49] Other animals may have very specific feeding behaviours, such as hawksbill sea turtles which mainly eat sponges.[50]

Hydrothermal vent mussels and shrimps

Most animals rely on biomass and bioenergy produced by plants and phytoplanktons (collectively called producers) through photosynthesis. Herbivores, as primary consumers, eat the plant material directly to digest and absorb the nutrients, while carnivores and other animals on higher trophic levels indirectly acquire the nutrients by eating the herbivores or other animals that have eaten the herbivores. Animals oxidize carbohydrates, lipids, proteins and other biomolecules, which allows the animal to grow and to sustain basal metabolism and fuel other biological processes such as locomotion.[51][52][53] Some benthic animals living close to hydrothermal vents and cold seeps on the dark sea floor consume organic matter produced through chemosynthesis (via oxidizing inorganic compounds such as hydrogen sulfide) by archaea and bacteria.[54]

Animals evolved in the sea. Lineages of arthropods colonised land around the same time as land plants, probably between 510 and 471 million years ago during the Late Cambrian or Early Ordovician.[55] Vertebrates such as the lobe-finned fish Tiktaalik started to move on to land in the late Devonian, about 375 million years ago.[56][57] Animals occupy virtually all of earth's habitats and microhabitats, with faunas adapted to salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of other organisms.[58] Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F)[59] or in the most extreme cold deserts of continental Antarctica.[60]

Diversity

Size

The blue whale is the largest animal that has ever lived.

The blue whale (Balaenoptera musculus) is the largest animal that has ever lived, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long.[61][62][63] The largest extant terrestrial animal is the African bush elephant (Loxodonta africana), weighing up to 12.25 tonnes[61] and measuring up to 10.67 metres (35.0 ft) long.[61] The largest terrestrial animals that ever lived were titanosaur sauropod dinosaurs such as Argentinosaurus, which may have weighed as much as 73 tonnes, and Supersaurus which may have reached 39 meters.[64][65] Several animals are microscopic; some Myxozoa (obligate parasites within the Cnidaria) never grow larger than 20 μm,[66] and one of the smallest species (Myxobolus shekel) is no more than 8.5 μm when fully grown.[67]

Numbers and habitats of major phyla

The following table lists estimated numbers of described extant species for the major animal phyla,[68] along with their principal habitats (terrestrial, fresh water,[69] and marine),[70] and free-living or parasitic ways of life.[71] Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.[72] Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.[73][74][b]

Phylum Example Described species Land Sea Freshwater Free-living Parasitic
Arthropoda wasp 1,257,000[68] Yes 1,000,000
(insects)[76]
Yes >40,000
(Malac-
ostraca
)[77]
Yes 94,000[69] Yes[70] Yes >45,000[c][71]
Mollusca snail 85,000[68]
107,000[78]
Yes 35,000[78] Yes 60,000[78] Yes 5,000[69]
12,000[78]
Yes[70] Yes >5,600[71]
Chordata green spotted frog facing right >70,000[68][79] Yes 23,000[80] Yes 13,000[80] Yes 18,000[69]
9,000[80]
Yes Yes 40
(catfish)[81][71]
Platyhelminthes 29,500[68] Yes[82] Yes[70] Yes 1,300[69] Yes[70]

3,000–6,500[83]

Yes >40,000[71]

4,000–25,000[83]

Nematoda 25,000[68] Yes (soil)[70] Yes 4,000[72] Yes 2,000[69] Yes
11,000[72]
Yes 14,000[72]
Annelida 17,000[68] Yes (soil)[70] Yes[70] Yes 1,750[69] Yes Yes 400[71]
Cnidaria Table coral 16,000[68] Yes[70] Yes (few)[70] Yes[70] Yes >1,350
(Myxozoa)[71]
Porifera 10,800[68] Yes[70] 200–300[69] Yes Yes[84]
Echinodermata 7,500[68] Yes 7,500[68] Yes[70]
Bryozoa 6,000[68] Yes[70] Yes 60–80[69] Yes
Rotifera 2,000[68] Yes >400[85] Yes 2,000[69] Yes
Nemertea 1,350[86][87] Yes Yes Yes
Tardigrada 1,335[68] Yes[88]
(moist plants)
Yes Yes Yes
Total number of described extant species as of 2013: 1,525,728[68]

Evolutionary origin

Evidence of animals is found as long ago as the Cryogenian period. 24-Isopropylcholestane (24-ipc) has been found in rocks from roughly 650 million years ago; it is only produced by sponges and pelagophyte algae. Its likely origin is from sponges based on molecular clock estimates for the origin of 24-ipc production in both groups. Analyses of pelagophyte algae consistently recover a Phanerozoic origin, while analyses of sponges recover a Neoproterozoic origin, consistent with the appearance of 24-ipc in the fossil record.[89][90]

The first body fossils of animals appear in the Ediacaran, represented by forms such as Charnia and Spriggina. It had long been doubted whether these fossils truly represented animals,[91][92][93] but the discovery of the animal lipid cholesterol in fossils of Dickinsonia establishes their nature.[94] Animals are thought to have originated under low-oxygen conditions, suggesting that they were capable of living entirely by anaerobic respiration, but as they became specialized for aerobic metabolism they became fully dependent on oxygen in their environments.[95]

Many animal phyla first appear in the fossil record during the Cambrian explosion, starting about 539 million years ago, in beds such as the Burgess shale.[96] Extant phyla in these rocks include molluscs, brachiopods, onychophorans, tardigrades, arthropods, echinoderms and hemichordates, along with numerous now-extinct forms such as the predatory Anomalocaris. The apparent suddenness of the event may however be an artifact of the fossil record, rather than showing that all these animals appeared simultaneously.[97][98][99][100] That view is supported by the discovery of Auroralumina attenboroughii, the earliest known Ediacaran crown-group cnidarian (557–562 mya, some 20 million years before the Cambrian explosion) from Charnwood Forest, England. It is thought to be one of the earliest predators, catching small prey with its nematocysts as modern cnidarians do.[101]

Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago.[102] Early fossils that might represent animals appear for example in the 665-million-year-old rocks of the Trezona Formation of South Australia. These fossils are interpreted as most probably being early sponges.[103] Trace fossils such as tracks and burrows found in the Tonian period (from 1 gya) may indicate the presence of triploblastic worm-like animals, roughly as large (about 5 mm wide) and complex as earthworms.[104] However, similar tracks are produced by the giant single-celled protist Gromia sphaerica, so the Tonian trace fossils may not indicate early animal evolution.[105][106] Around the same time, the layered mats of microorganisms called stromatolites decreased in diversity, perhaps due to grazing by newly evolved animals.[107] Objects such as sediment-filled tubes that resemble trace fossils of the burrows of wormlike animals have been found in 1.2 gya rocks in North America, in 1.5 gya rocks in Australia and North America, and in 1.7 gya rocks in Australia. Their interpretation as having an animal origin is disputed, as they might be water-escape or other structures.[108][109]

Phylogeny

External phylogeny

Animals are monophyletic, meaning they are derived from a common ancestor. Animals are the sister group to the choanoflagellates, with which they form the Choanozoa.[110] The dates on the phylogenetic tree indicate approximately how many millions of years ago (mya) the lineages split.[111][112][113][114][115]

Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines.[116]

Opisthokonta

Holomycota (inc. fungi)

Holozoa
1100 mya
1300 mya

Internal phylogeny

The most basal animals, the Porifera, Ctenophora, Cnidaria, and Placozoa, have body plans that lack bilateral symmetry. Their relationships are still disputed; the sister group to all other animals could be the Porifera or the Ctenophora,[117] both of which lack hox genes, which are important for body plan development.[118]

Hox genes are found in the Placozoa,[119][120] Cnidaria,[121] and Bilateria.[122][123] 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian. 25 of these are novel core gene groups, found only in animals; of those, 8 are for essential components of the Wnt and TGF-beta signalling pathways which may have enabled animals to become multicellular by providing a pattern for the body's system of axes (in three dimensions), and another 7 are for transcription factors including homeodomain proteins involved in the control of development.[124][125]

Giribet and Edgecombe (2020) provide what they consider to be a consensus internal phylogeny of the animals, embodying uncertainty about the structure at the base of the tree (dashed lines).[126]

An alternative phylogeny, from Kapli and colleagues (2021), proposes a clade Xenambulacraria for the Xenacoelamorpha + Ambulacraria; this is either within Deuterostomia, as sister to Chordata, or the Deuterostomia are recovered as paraphyletic, and Xenambulacraria is sister to the proposed clade Centroneuralia, consisting of Chordata + Protostomia.[127]

Non-bilateria

Non-bilaterians include sponges (centre) and corals (background).

Several animal phyla lack bilateral symmetry. These are the Porifera (sea sponges), Placozoa, Cnidaria (which includes jellyfish, sea anemones, and corals), and Ctenophora (comb jellies).

Sponges are physically very distinct from other animals, and were long thought to have diverged first, representing the oldest animal phylum and forming a sister clade to all other animals.[128] Despite their morphological dissimilarity with all other animals, genetic evidence suggests sponges may be more closely related to other animals than the comb jellies are.[129][130] Sponges lack the complex organization found in most other animal phyla;[131] their cells are differentiated, but in most cases not organised into distinct tissues, unlike all other animals.[132] They typically feed by drawing in water through pores, filtering out small particles of food.[133]

The comb jellies and Cnidaria are radially symmetric and have digestive chambers with a single opening, which serves as both mouth and anus.[134] Animals in both phyla have distinct tissues, but these are not organised into discrete organs.[135] They are diploblastic, having only two main germ layers, ectoderm and endoderm.[136]

The tiny placozoans have no permanent digestive chamber and no symmetry; they superficially resemble amoebae.[137][138] Their phylogeny is poorly defined, and under active research.[129][139]

Bilateria

Idealised bilaterian body plan.[d] With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion.

The remaining animals, the great majority—comprising some 29 phyla and over a million species—form a clade, the Bilateria, which have a bilaterally symmetric body plan. The Bilateria are triploblastic, with three well-developed germ layers, and their tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is an internal body cavity, a coelom or pseudocoelom. These animals have a head end (anterior) and a tail end (posterior), a back (dorsal) surface and a belly (ventral) surface, and a left and a right side.[140][141]

Having a front end means that this part of the body encounters stimuli, such as food, favouring cephalisation, the development of a head with sense organs and a mouth. Many bilaterians have a combination of circular muscles that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body;[141] these enable soft-bodied animals with a hydrostatic skeleton to move by peristalsis.[142] They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary larvae which swim with cilia and have an apical organ containing sensory cells. However, over evolutionary time, descendant spaces have evolved which have lost one or more of each of these characteristics. For example, adult echinoderms are radially symmetric (unlike their larvae), while some parasitic worms have extremely simplified body structures.[140][141]

Genetic studies have considerably changed zoologists' understanding of the relationships within the Bilateria. Most appear to belong to two major lineages, the protostomes and the deuterostomes.[143] It is often suggested that the basalmost bilaterians are the Xenacoelomorpha, with all other bilaterians belonging to the subclade Nephrozoa.[144][145][146] However, this suggestion has been contested, with other studies finding that xenacoelomorphs are more closely related to Ambulacraria than to other bilaterians.[127]

Protostomes and deuterostomes

The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus.

Protostomes and deuterostomes differ in several ways. Early in development, deuterostome embryos undergo radial cleavage during cell division, while many protostomes (the Spiralia) undergo spiral cleavage.[147] Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the embryonic gut develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily.[148][149] Most protostomes have schizocoelous development, where cells simply fill in the interior of the gastrula to form the mesoderm. In deuterostomes, the mesoderm forms by enterocoelic pouching, through invagination of the endoderm.[150]

The main deuterostome phyla are the Echinodermata and the Chordata.[151] Echinoderms are exclusively marine and include starfish, sea urchins, and sea cucumbers.[152] The chordates are dominated by the vertebrates (animals with backbones),[153] which consist of fishes, amphibians, reptiles, birds, and mammals.[154] The deuterostomes also include the Hemichordata (acorn worms).[155][156]

Ecdysozoa
Ecdysis: a dragonfly has emerged from its dry exuviae and is expanding its wings. Like other arthropods, its body is divided into segments.

The Ecdysozoa are protostomes, named after their shared trait of ecdysis, growth by moulting.[157] They include the largest animal phylum, the Arthropoda, which contains insects, spiders, crabs, and their kin. All of these have a body divided into repeating segments, typically with paired appendages. Two smaller phyla, the Onychophora and Tardigrada, are close relatives of the arthropods and share these traits. The ecdysozoans also include the Nematoda or roundworms, perhaps the second largest animal phylum. Roundworms are typically microscopic and occur in nearly every environment where there is water;[158] some are important parasites.[159] Smaller phyla related to them are the Nematomorpha or horsehair worms, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.[160]

Spiralia
Spiral cleavage in a sea snail embryo

The Spiralia are a large group of protostomes that develop by spiral cleavage in the early embryo.[161] The Spiralia's phylogeny has been disputed, but it contains a large clade, the superphylum Lophotrochozoa, and smaller groups of phyla such as the Rouphozoa which includes the gastrotrichs and the flatworms. All of these are grouped as the Platytrochozoa, which has a sister group, the Gnathifera, which includes the rotifers.[162][163]

The Lophotrochozoa includes the molluscs, annelids, brachiopods, nemerteans, bryozoa and entoprocts.[162][164][165] The molluscs, the second-largest animal phylum by number of described species, includes snails, clams, and squids, while the annelids are the segmented worms, such as earthworms, lugworms, and leeches. These two groups have long been considered close relatives because they share trochophore larvae.[166][167]

History of classification

Jean-Baptiste de Lamarck led the creation of a modern classification of invertebrates, breaking up Linnaeus's "Vermes" into 9 phyla by 1809.[168]

In the classical era, Aristotle divided animals,[e] based on his own observations, into those with blood (roughly, the vertebrates) and those without. The animals were then arranged on a scale from man (with blood, 2 legs, rational soul) down through the live-bearing tetrapods (with blood, 4 legs, sensitive soul) and other groups such as crustaceans (no blood, many legs, sensitive soul) down to spontaneously generating creatures like sponges (no blood, no legs, vegetable soul). Aristotle was uncertain whether sponges were animals, which in his system ought to have sensation, appetite, and locomotion, or plants, which did not: he knew that sponges could sense touch and would contract if about to be pulled off their rocks, but that they were rooted like plants and never moved about.[169]

In 1758, Carl Linnaeus created the first hierarchical classification in his Systema Naturae.[170] In his original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then, the last four have all been subsumed into a single phylum, the Chordata, while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by Jean-Baptiste de Lamarck, who called the Vermes une espèce de chaos (a chaotic mess)[f] and split the group into three new phyla: worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his Philosophie Zoologique, Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely cirripedes, annelids, crustaceans, arachnids, insects, worms, radiates, polyps, and infusorians.[168]

In his 1817 Le Règne Animal, Georges Cuvier used comparative anatomy to group the animals into four embranchements ("branches" with different body plans, roughly corresponding to phyla), namely vertebrates, molluscs, articulated animals (arthropods and annelids), and zoophytes (radiata) (echinoderms, cnidaria and other forms).[172] This division into four was followed by the embryologist Karl Ernst von Baer in 1828, the zoologist Louis Agassiz in 1857, and the comparative anatomist Richard Owen in 1860.[173]

In 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms: Metazoa (multicellular animals, with five phyla: coelenterates, echinoderms, articulates, molluscs, and vertebrates) and Protozoa (single-celled animals), including a sixth animal phylum, sponges.[174][173] The protozoa were later moved to the former kingdom Protista, leaving only the Metazoa as a synonym of Animalia.[175]

In human culture

Practical uses

Sides of beef in a slaughterhouse

The human population exploits a large number of other animal species for food, both of domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species.[176][177] Marine fish of many species are caught commercially for food. A smaller number of species are farmed commercially.[176][178][179] Humans and their livestock make up more than 90% of the biomass of all terrestrial vertebrates, and almost as much as all insects combined.[180]

Invertebrates including cephalopods, crustaceans, and bivalve or gastropod molluscs are hunted or farmed for food.[181] Chickens, cattle, sheep, pigs, and other animals are raised as livestock for meat across the world.[177][182][183] Animal fibres such as wool are used to make textiles, while animal sinews have been used as lashings and bindings, and leather is widely used to make shoes and other items. Animals have been hunted and farmed for their fur to make items such as coats and hats.[184] Dyestuffs including carmine (cochineal),[185][186] shellac,[187][188] and kermes[189][190] have been made from the bodies of insects. Working animals including cattle and horses have been used for work and transport from the first days of agriculture.[191]

Animals such as the fruit fly Drosophila melanogaster serve a major role in science as experimental models.[192][193][194][195] Animals have been used to create vaccines since their discovery in the 18th century.[196] Some medicines such as the cancer drug trabectedin are based on toxins or other molecules of animal origin.[197]

A gun dog retrieving a duck during a hunt

People have used hunting dogs to help chase down and retrieve animals,[198] and birds of prey to catch birds and mammals,[199] while tethered cormorants have been used to catch fish.[200] Poison dart frogs have been used to poison the tips of blowpipe darts.[201][202] A wide variety of animals are kept as pets, from invertebrates such as tarantulas, octopuses, and praying mantises,[203] reptiles such as snakes and chameleons,[204] and birds including canaries, parakeets, and parrots[205] all finding a place. However, the most kept pet species are mammals, namely dogs, cats, and rabbits.[206][207][208] There is a tension between the role of animals as companions to humans, and their existence as individuals with rights of their own.[209]

A wide variety of terrestrial and aquatic animals are hunted for sport.[210]

Symbolic uses

The signs of the Western and Chinese zodiacs are based on animals.[211][212] In China and Japan, the butterfly has been seen as the personification of a person's soul,[213] and in classical representation the butterfly is also the symbol of the soul.[214][215]

Artistic vision: Still Life with Lobster and Oysters by Alexander Coosemans, c. 1660

Animals have been the subjects of art from the earliest times, both historical, as in ancient Egypt, and prehistoric, as in the cave paintings at Lascaux. Major animal paintings include Albrecht Dürer's 1515 The Rhinoceros, and George Stubbs's c. 1762 horse portrait Whistlejacket.[216] Insects, birds and mammals play roles in literature and film,[217] such as in giant bug movies.[218][219][220]

Animals including insects[213] and mammals[221] feature in mythology and religion. The scarab beetle was sacred in ancient Egypt,[222] and the cow is sacred in Hinduism.[223] Among other mammals, deer,[221] horses,[224] lions,[225] bats,[226] bears,[227] and wolves[228] are the subjects of myths and worship.

See also

Notes

  1. ^ Henneguya zschokkei does not have mitochondrial DNA or utilize aerobic respiration.[19]
  2. ^ The application of DNA barcoding to taxonomy further complicates this; a 2016 barcoding analysis estimated a total count of nearly 100,000 insect species for Canada alone, and extrapolated that the global insect fauna must be in excess of 10 million species, of which nearly 2 million are in a single fly family known as gall midges (Cecidomyiidae).[75]
  3. ^ Not including parasitoids.[71]
  4. ^ Compare File:Annelid redone w white background.svg for a more specific and detailed model of a particular phylum with this general body plan.
  5. ^ In his History of Animals and Parts of Animals.
  6. ^ The French prefix une espèce de is pejorative.[171]

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