Anifail: Gwahaniaeth rhwng fersiynau
Cynnwys wedi'i ddileu Cynnwys wedi'i ychwanegu
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ehangu Tagiau: Golygiad cod 2017 |
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Llinell 57:
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Pan yn siarad yn gyffredinol am anifeiliaid, nid yw'n cynnwys [[bod dynol|bodau dynol]] yn aml, ond mewn gwirionedd mae dyn yn anifail, hefyd.<ref>{{cite web |url=http://m-w.com/dictionary/animals |title=''Animals'' |publisher=[[Merriam-Webster's]] |quote=2 a : ''one of the lower animals as distinguished from human beings'' b : ''mammal''; ''broadly'' : ''vertebrate'' |accessdate=16 May 2010}}</ref>
Llinell 63:
Yn ystod y [[Cambriaidd|cyfnod Cambriaidd]] yr ymddangosodd y [[ffylwm]] anifail, a hynny oddeutu 542 miliwn o flynyddoedd yn ôl; gwelwn hyn yn y dystiolaeth o [[ffosil]]iau o'r cyfnod. Rhennir y grwp 'anifeiliaid' yn isgrwpiau, gan gynnwys: [[aderyn|adar]], [[mamal]]iaid, [[amffibiad|amffibiaid]], [[ymlusgiad|ymlusgiaid]], [[pysgodyn|pysgod]] a [[pryf]]aid.
O ran dosbarthiad, mae'r rhan fwyaf o rywogaethau o anifeiliaid yn byw mewn [[Bilateria]] (hy anifeiliaid gyda chymesured dwyochr), ac yn cynnwys y [[Protostomia|protostomau]], sy'n cynnwys [[Infertebrat|infertebratau]] megis [[Llyngyren gron|nematodau]], [[Arthropod|arthropodau]], a [[Molwsg|molysgiaid]], a'r deuterostomau, sy'n cynnwys yr [[Echinoderm|echinodermau]] a'r [[Cordog|cordadau]], gyda'r olaf yn ffylwm o anifeiliaid sy'n cynnwys y [[Fertebrat|fertebratau]]. Roedd ffurfiau bywyd a ddehonglir fel anifeiliaid cynnar yn bresennol ym biota Ediacaraidd y [[Cyn-Gambriaidd]] diweddar. Daeth llawer o [[Ffylwm|ffyla]] anifeiliaid modern yn amlwg yn y [[Ffosil|cofnod ffosil]] fel rhywogaethau morol yn ystod y ffrwydrad Cambriaidd, a ddechreuodd tua 542 miliwn o flynyddoedd yn ôl. mae 6,331 o grwpiau o [[Genyn|enynnau]] sy'n gyffredin i bob anifail byw wedi'u cofnodi; gall y rhain fod wedi codi o un hynafiad cyffredin a oedd yn byw [[Rhewlifiant Cryogenaidd|650 miliwn]] o flynyddoedd [[cyn y presennol]] (CP).
Yn hanesyddol, dosbarthodd Aristotle anifeiliaid i'r rhai â gwaed a'r rhai heb waed. Creodd [[Carolus Linnaeus|Carl Linnaeus]] y dosbarthiad biolegol hierarchaidd cyntaf ar gyfer anifeiliaid ym 1758 gyda'i ''Systema Naturae'', ac ehangwyd gan [[Jean-Baptiste de Lamarck|Jean-Baptiste Lamarck]] i 14 [[ffylwm]] erbyn 1809. Ym 1874, rhannodd [[Ernst Haeckel]] y deyrnas anifeiliaid i'r Metasoa amlgellog (sy'n [[Cyfystyr (tacsonomeg)|gyfystyr]] bellach ag [[Animalia]]) a'r [[protosoa|Protozoa]], [[Organeb ungellog|organebau ungellog]] nad oeddent bellach yn cael eu hystyried yn anifeiliaid. Yn y cyfnod modern, mae dosbarthiad biolegol anifeiliaid yn dibynnu ar dechnegau uwch, megis ffylogeneteg moleciwlaidd, sy'n effeithiol wrth ddangos y berthynas [[Esblygiad|esblygiadol]] rhwng y gwahanol [[Tacson|tacsa]].
Mae [[Bod dynol|bodau dynol yn]] defnyddio llawer iawn o rywogaethau o anifeiliaid i'w ddibenion a'i bwrpas ei hun, megis ar gyfer bwyd (gan gynnwys [[cig]], [[llaeth]], ac wyau), ar gyfer deunyddiau (fel [[lledr]], [[sidan]] a [[gwlân]]), fel [[Anifail anwes|anifeiliaid anwes]], ac fel anifeiliaid gwaith gan gynnwys ar gyfer cludo. Defnyddiwyd cŵn i hela, yn ogystal ag adar ysglyfaethus, tra bod llawer o anifeiliaid daearol a dyfrol yn cael eu hela ar gyfer chwaraeon. Mae anifeiliaid wedi ymddangos mewn celf o'r amseroedd cynharaf ac yn cael sylw mewn mytholeg a chrefydd.
Mae'r [[hwiangerdd]] Gymraeg [[Pais Dinogad]] yn nodi llawer o anifeiliad oedd yn cael eu hela gan dad y plentyn:
[[File:Lascaux painting.jpg chwith|chwith|bawd|Peintiad o Ogof Lascaux: gwartheg (''Bos primigenius),'' ceffylau a cheirw]]
: Peis dinogat e vreith vreith (Pais Dinogad sydd fraith, fraith,)
: o grwyn balaot ban wreith (O groen y [[bela]] y mae'i waith)
== Geirdarddiad ==
Benthyciwyd y gair Cymraeg ''anifail'' o'r Lladin animalia, o bosib yng nghyfnod y Rhufeiniaid. Daw [[Animalia|''animalia'']] o'r Lladin ''animalis'', sy'n golygu 'gydag anadl' neu 'gydag enaid' hy 'bod yn fyw'.<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> Mae'r diffiniad biolegol yn cynnwys holl aelodau'r deyrnas Animalia. Ar lafar defnyddir y term ''anifail'' yn aml i gyfeirio at unrhyw anifail nad yw'n fod dynol.<ref>{{Cite web|website=English Oxford Living Dictionaries|title=animal|url=https://en.oxforddictionaries.com/definition/animal|access-date=26 July 2018|archiveurl=https://web.archive.org/web/20180726233938/https://en.oxforddictionaries.com/definition/animal|archivedate=26 July 2018}}</ref><ref>{{Cite journal|last=Boly|first7=David|pmc=3814086|doi=10.3389/fpsyg.2013.00625|pages=625|volume=4|journal=[[Frontiers in Psychology]]|title=Consciousness in humans and non-human animals: recent advances and future directions|date=2013|first8=Naotsugu|last8=Tsuchiya|last7=Edelman|first=Melanie|first6=Steven|last6=Laureys|first5=Bernard|last5=Baars|first4=Paul|last4=Ingmundson|first3=Melanie|last3=Wilke|first2=Anil K.|last2=Seth|pmid=24198791}}</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|archiveurl=https://web.archive.org/web/20180612140908/https://royalsociety.org/topics-policy/publications/2004/non-human-animals/|archivedate=12 June 2018}}</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|archiveurl=https://web.archive.org/web/20180612142932/https://www.collinsdictionary.com/dictionary/english/nonhuman|archivedate=12 June 2018}}</ref><ref>{{cite book|last=Cresswell|first=Julia|title=''The Oxford Dictionary of Word Origins''|url=https://archive.org/details/oxforddictionary0000unse_p6k3|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><ref name=americanheritage_animal>{{cite encyclopedia |year=2006 |title=Animal |encyclopedia=The American Heritage Dictionary |publisher=Houghton Mifflin Company |edition=4th}}</ref>
== Nodweddion ==
[[Delwedd:Blastulation.png|bawd| Mae anifeiliaid yn unigryw oherwydd bod pelen celloedd yr embryo cynnar (1) yn datblygu'n bêl wag neu'n blastwla (2).]]
Mae gan anifeiliaid sawl nodwedd sy'n eu gosod ar wahân i bethau byw eraill. Mae anifeiliaid yn [[Ewcaryot|ewcaryotig]] ac yn [[Organeb amlgellog|organebau amlgellog]].<ref name="Avila1995">{{Cite book|last=Avila|first=Vernon L.|title=Biology: Investigating Life on Earth|url=https://books.google.com/books?id=B_OOazzGefEC&pg=PA767|year=1995|publisher=[[Jones & Bartlett Learning]]|isbn=978-0-86720-942-6|pages=767–}}</ref><ref name="palaeos">{{Cite web|title=Palaeos:Metazoa|url=http://palaeos.com/metazoa/metazoa.html|website=Palaeos|access-date=25 February 2018|archiveurl=https://web.archive.org/web/20180228005641/http://palaeos.com/metazoa/metazoa.html|archivedate=28 February 2018}}</ref> Yn wahanol i blanhigion ac [[Alga|algâu]], sy'n cynhyrchu eu maetholion eu hunain,<ref name="AnimalCells">{{Cite web|last=Davidson|first=Michael W.|title=Animal Cell Structure|url=http://micro.magnet.fsu.edu/cells/animalcell.html|access-date=20 September 2007|archiveurl=https://web.archive.org/web/20070920235924/http://micro.magnet.fsu.edu/cells/animalcell.html|archivedate=20 September 2007}}</ref> mae anifeiliaid yn heterotroffig,<ref name="palaeos" /><ref name="Windows">{{Cite web|last=Bergman|first=Jennifer|title=Heterotrophs|url=http://www.windows.ucar.edu/tour/link=/earth/Life/heterotrophs.html&edu=high|access-date=30 September 2007|archiveurl=https://web.archive.org/web/20070829051950/http://www.windows.ucar.edu/tour/link%3D/earth/Life/heterotrophs.html%26edu%3Dhigh|archivedate=29 August 2007}}</ref> yn bwydo ar ddeunydd organig ac yn ei dreulio'n fewnol.<ref>{{Cite journal|last=Douglas|first=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> Gydag ychydig iawn o eithriadau, (enghraifft; ''Henneguya zschokkei'' <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|work=CNN|date=26 February 2020|access-date=2020-02-28}}</ref>) mae anifeiliaid yn [[Resbiradaeth cellog|resbiradu yn aerobig]].<ref name="oxygen">{{Cite journal|last=Mentel|first=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}}</ref> Mae pob anifail yn symudol<ref name="Concepts">{{Cite web|url=http://employees.csbsju.edu/SSAUPE/biol116/Zoology/digestion.htm|last=Saupe|first=S. G.|title=Concepts of Biology|access-date=30 September 2007|archiveurl=https://web.archive.org/web/20071121084100/http://employees.csbsju.edu/SSAUPE/biol116/Zoology/digestion.htm|archivedate=21 November 2007}}</ref> (yn gallu symud eu cyrff yn ddigymell) yn ystod rhan neu'r cyfan o'u [[Cylchred bywyd|cylch bywyd]], ond mae rhai anifeiliaid, megis [[Sbwng|sbyngau]], [[Cwrel|cwrelau]], cregyn gleision a [[Gwyran|chregyn llong]] (neu gwyran), yn dod yn ddigoes tua diwedd eu bywydau. Mae'r blastula yn gyfnod yn y datblygiad embryonig sy'n unigryw i anifeiliaid,<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> (er ei fod wedi'i golli mewn rhai) gan ganiatáu gwahaniaethu celloedd i feinweoedd ac organau arbenigol, cymhleth.
=== Strwythur ===
Mae pob anifail yn cynnwys celloedd, wedi'u hamgylchynu gan fatrics allgellog (''extracellular matrix'') sy'n cynnwys [[Collagen|colagen]] a glycoproteinau elastig.<ref>{{Cite book|last=Alberts|last6=Walter|isbn=978-0-8153-3218-3|url=https://www.ncbi.nlm.nih.gov/books/NBK26810/|publisher=[[Garland Science]]|year=2002|edition=4th|title=Molecular Biology of the Cell|first6=Peter|first5=Keith|first=Bruce|last5=Roberts|first4=Martin|last4=Raff|first3=Julian|last3=Lewis|first2=Alexander|last2=Johnson|access-date=29 August 2017}}</ref> Yn ystod datblygiad, mae matrics allgellog anifeiliaid yn ffurfio fframwaith cymharol hyblyg lle gall celloedd symud o gwmpas ac ad-drefnu eu hunain, gan ei gwneud yn bosibl ffurfio strwythurau cymhleth. Gall y ffurfiau hyn fod o [[Calchfaen|galch]] ee strwythurau fel cregyn, [[Asgwrn|esgyrn]], a sbigylau sbwng.<ref>{{Cite book|last=Sangwal|first=Keshra|title=Additives and crystallization processes: from fundamentals to applications|url=https://archive.org/details/additivescrystal00sang|year=2007|publisher=[[John Wiley and Sons]]|isbn=978-0-470-06153-4|page=[https://archive.org/details/additivescrystal00sang/page/n228 212]}}</ref> Mewn cyferbyniad, mae celloedd organebau amlgellog eraill (algae, planhigion a ffyngau'n bennaf) yn cael eu dal yn eu lle gan gellfuriau, ac felly'n dibynu ar dyfiant cynyddol.<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> Mae celloedd anifeiliaid yn unigryw ac yn meddu ar y cyffyrdd cell (''cell junctions'') elwir yn gyffyrdd tynn, cyffyrdd bwlch, a desmosomau.<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>
Gydag ychydig iawn o eithriadau - yn arbennig, y sbyngau a'r placozoans - mae cyrff anifeiliaid yn gymysgedd o wahanol [[Meinwe|feinweoedd]],<ref>{{Cite book|last=Starr|first=Cecie|url=https://books.google.com/books?id=EXNFwB-O-WUC&pg=PA362|title=Biology: Concepts and Applications without Physiology|year=2007|publisher=Cengage Learning|isbn=978-0-495-38150-1|pages=362, 365}}</ref> gan gynnwys [[cyhyrau]], sy'n galluogi symudiad, a meinweoedd nerfol, sy'n trosglwyddo signalau ac yn cydlynu'r corff. Yn nodweddiadol, mae yna hefyd [[Treulio bwyd|siambr dreulio]] fewnol gyda naill ai un agoriad (yn Ctenophora, Cnidaria, a llyngyr lledog) neu ddau agoriad (yn y rhan fwyaf o bilateriaid), y ceg a'r anws.<ref>{{Cite book|last=Hillmer|first=Gero|last2=Lehmann|first2=Ulrich|others=Translated by J. Lettau|title=Fossil Invertebrates|year=1983|publisher=CUP Archive|isbn=978-0-521-27028-1|page=54|url=https://books.google.com/books?id=9jE4AAAAIAAJ&pg=PA54|access-date=8 January 2016}}</ref>
=== Atgynhyrchu a datblygu ===
[[Delwedd:Odonata_copulation.jpg|chwith|bawd| Mae [[atgenhedlu rhywiol]] bron yn gyffredinol mewn anifeiliaid, fel y [[Gwas neidr|gweision neidr]] hyn.]]
Mae bron pob anifail yn defnyddio rhyw fath o [[atgenhedlu rhywiol]].<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> Cynhyrchant gametau haploid trwy [[Meiosis|feiosis]]; mae'r gametau symudol llai yn sbermatosoa a'r gametau ansymudol mwyaf yw ofa.<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> Mae'r rhain yn asio i ffurfio [[Sygot|sygotau]],<ref>{{Cite book|last=Hamilton|first=Matthew B.|title=Population genetics|url=https://archive.org/details/populationgeneti00hami|year=2009|publisher=[[Wiley-Blackwell]]|isbn=978-1-4051-3277-0|page=[https://archive.org/details/populationgeneti00hami/page/n69 55]}}</ref> sy'n datblygu trwy [[mitosis]] yn sffêr gwag, a elwir yn blastwla. Mewn sbyngau, mae larfa blastula yn nofio i leoliad newydd, yn glynu wrth wely'r môr, ac yn datblygu'n sbwng newydd.<ref>{{Cite book|last=Ville|first=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> Yn y rhan fwyaf o grwpiau eraill, mae'r blastula yn cael ei aildrefnu'n fwy cymhleth.<ref>{{Cite book|last=Hamilton|first=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> Mae'n ymweinio (o'r gair 'gwain') yn gyntaf, i ffurfio gastrwla gyda siambr dreulio a dwy haen germ ar wahân, ectoderm allanol ac endoderm mewnol.<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> Yn y rhan fwyaf o achosion, mae trydedd haen germ, y mesoderm, hefyd yn datblygu rhyngddynt.<ref>{{Cite book|title=The Encyclopedia Americana: a library of universal knowledge, Volume 10|year=1918|publisher=Encyclopedia Americana Corp.|page=281}}</ref> Yna mae'r haenau germ hyn yn gwahaniaethu i ffurfio meinweoedd ac organau. <ref>{{Cite book|last=Romoser|first=William S.|author-link=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>
Mae achosion mynych o baru gyda pherthynas agos (yn ystod atgenhedlu rhywiol) yn gyffredinol yn arwain at iselder mewnfridio o fewn poblogaeth ac yn niweidiol.<ref name="pmid19834483">{{Cite journal|last=Charlesworth|first=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}}</ref><ref name="pmid3324702">{{Cite book|last=Bernstein|first=H.|last2=Hopf|first2=F. A.|last3=Michod|first3=R. E.|title=The molecular basis of the evolution of sex|volume=24|pages=323–370|year=1987|pmid=3324702|doi=10.1016/s0065-2660(08)60012-7|isbn=978-0-12-017624-3}}</ref> Mae anifeiliaid wedi datblygu nifer o fecanweithiau ar gyfer osgoi mewnfridio agos (neu [[llosgach]]).<ref name="Pusey">{{Cite journal|last=Pusey|first=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}}</ref>
Mae rhai anifeiliaid yn gallu [[atgenhedlu anrhywiol]], sy'n aml yn arwain at glôn genetig y rhiant. Gall hyn ddigwydd trwy tmddarnio; egino, megis yn ''Hydra'' a [[Cnidariad|cnidariaid]] eraill; neu parthenogenesis, lle cynhyrchir wyau ffrwythlon heb baru, megis mewn [[Pryf glas|pryfed gleision]] (affid).<ref>{{Cite book|last=Adiyodi|first=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|last=Schatz|first=Phil|title=Concepts of Biology: How Animals Reproduce|url=http://philschatz.com/biology-concepts-book/contents/m45547.html|publisher=OpenStax College|access-date=5 March 2018|archiveurl=https://web.archive.org/web/20180306022745/http://philschatz.com/biology-concepts-book/contents/m45547.html|archivedate=6 March 2018}}</ref>
== Ecoleg ==
[[Delwedd:Ultramarine_Flycatcher_(Ficedula_superciliaris)_Naggar,_Himachal_Pradesh,_2013_(cropped).JPG|chwith|bawd| Mae [[Ysglyfaethwr|ysglyfaethwyr]], fel y [[gwybedog glas aelwyn]] hwn (''Ficedula superciliaris''), yn bwydo ar anifeiliaid eraill ee pryfaid]]
Mae anifeiliaid yn cael eu categoreiddio i [[Ecoleg|grwpiau ecolegol]] yn dibynnu ar sut y maent yn cael bwyd neu'n bwyta deunydd organig megis [[Cigysydd|cigysyddion]], [[Llysysydd|llysysyddion]], [[Hollysydd|hollysyddion]], ''detritivatores'',<ref>{{Cite book|last=Marchetti|first=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> a [[Arfilyn|pharasitiaid]].<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> Mae'r rhyngweithio rhwng anifeiliaid yn ffurfio gweoedd bwyd cymhleth. Mewn rhywogaethau cigysol neu hollysol, mae ''ysglyfaethwr'' yn bwydo ar [[organeb]] arall (a elwir yn ''ysglyfaeth'').<ref name="Ecology">{{Cite book|last=Begon|first=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> Mae'r pwysau parhaus rhwng yr ysglyfaethwr a'i ysglyfaeth yn arwain at gystadleuaeth esblygiadol gan arwain at wahanol addasiadau yng nghyrff yr anifeiliaid hyn.<ref>{{Cite book|last=Allen|first=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> Mae bron pob ysglyfaethwr amlgellog yn anifail.<ref name="SimpsonCB">{{Cite journal|last=Simpson|first=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}}</ref> Mae rhai defnyddwyr yn defnyddio nifer o ddulliau; er enghraifft, mewn gwenyn meirch parasitaidd, mae'r larfa'n bwydo ar feinwe byw y gwesteiwr, gan eu lladd yn y broses,<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/http://www.nature.com/scitable/knowledge/library/predation-herbivory-and-parasitism-13261134|archive-date=30 September 2017}}</ref> ond mae'r oedolion yn bwyta neithdar o flodau, yn bennaf.<ref>{{Cite journal|last=Jervis|first=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}}</ref> Gall fod gan anifeiliaid eraill ymddygiad bwydo penodol iawn, fel [[crwban Môr Gwalchbig]] sy'n bwyta [[Sbwng|sbyngau]]'n bennaf. <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}}</ref>
Mae'r rhan fwyaf o anifeiliaid yn dibynnu ar y biomas a'r egni a gynhyrchir gan blanhigion trwy [[ffotosynthesis]]. Mae [[Llysysydd|llysysyddion]] yn bwyta deunydd planhigion yn uniongyrchol, tra bod [[Cigysydd|cigysyddion]], ac anifeiliaid eraill ar lefelau troffig uwch fel arfer yn ei gaffael yn anuniongyrchol trwy fwyta anifeiliaid eraill. Mae anifeiliaid yn ocsideiddio [[Carbohydrad|carbohydradau]], [[Lipid|lipidau]], [[Protein|proteinau]], a biomoleciwlau eraill i ddatgloi egni cemegol ocsigen moleciwlaidd,<ref name="Schmidt-Rohr 2020">{{Cite journal|last=Schmidt-Rohr|first=Klaus|title=Oxygen is the High-Energy Molecule Powering Complex Multicellular Life: Fundamental Corrections to Traditional Bioenergetics|year=2020|journal=ACS Omega|volume=5|issue=5|pages=2221–2233|pmid=32064383|pmc=7016920|doi=10.1021/acsomega.9b03352}}</ref> sy'n caniatáu i'r anifail dyfu a chynnal prosesau biolegol megis [[ymsymudiad]].<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|last=Garrett|first=Reginald|last2=Grisham|first2=Charles M.|title=Biochemistry|url=https://archive.org/details/biochemistry00rhga|year=2010|publisher=Cengage Learning|isbn=978-0-495-10935-8|page=[https://archive.org/details/biochemistry00rhga/page/n572 535]}}</ref> Mae anifeiliaid sy'n byw yn agos at fentiau hydrothermol a diferion oer ar wely'r môr tywyll yn bwyta deunydd organig [[archaea]] a bacteria a gynhyrchir yn y lleoliadau hyn trwy chemosynthesis (trwy ocsideiddio cyfansoddion anorganig, fel hydrogen sylffid).<ref>{{Cite book|last=Castro|first=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>
Esblygodd anifeiliaid yn y môr yn wreiddiol. Cytrefodd llinachau o arthropodau'r tir tua'r un adeg â phlanhigion tir, yn ôl pob tebyg rhwng 510 a 471 miliwn o flynyddoedd yn ôl ([[CP]]) yn ystod y Cyfnod Cambriaidd Diweddar neu'r [[Ordofigaidd|Ordofigaidd Cynnar]].<ref name="Rota-Stabelli2013">{{Cite journal|last=Rota-Stabelli|first=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=10.1016/j.cub.2013.01.026|pmid=23375891}}</ref> Dechreuodd [[Fertebrat|fertebratau]] fel y pysgodyn asgellog ''Tiktaalik'' symud i'r tir yn y [[Defonaidd|Defonaidd hwyr]], tua 375 miliwn CP.<ref>{{Cite journal|last=Daeschler|first=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}}</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> Mae anifeiliaid, bellach, wedi meddiannu bron pob un o [[Cynefin|gynefinoedd]] a microgynefinoedd y ddaear, gan gynnwys dŵr hallt, fentiau hydrothermol, dŵr croyw, ffynhonnau poeth, corsydd, coedwigoedd, porfeydd, anialwch, aer, a thu mewn i anifeiliaid, planhigion, ffyngau a chreigiau.<ref name="Margulis">{{Cite book|last=Margulis|first=Lynn|author-link=Lynn Margulis|last2=Schwartz, Karlene V.|last3=Dolan, Michael|title=Diversity of Life: The Illustrated Guide to the Five Kingdoms|url=https://books.google.com/books?id=8wJXWBMsEOkC&pg=PA115|year=1999|publisher=Jones & Bartlett Learning|isbn=978-0-7637-0862-7|pages=115–116}}</ref> Fodd bynnag, nid yw anifeiliaid yn gallu goddef gwres yn arbennig o dda; ychydig iawn ohonynt sy'n gallu goroesi ar dymheredd cyson uwchlaw {{Convert|50|°C|0}}.<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=http://nora.nerc.ac.uk/id/eprint/507274/1/Clarke.pdf|archive-url=https://web.archive.org/web/20190424155004/http://nora.nerc.ac.uk/id/eprint/507274/1/Clarke.pdf|archive-date=24 April 2019|doi=10.1017/S1473550413000438}}</ref> Ac ar ochr arall y geiniog, dim ond ychydig iawn o rywogaethau o anifeiliaid ([[Llyngyren gron|nematodau]]'n bennaf) all fyw yn niffeithdiroedd oer mwyaf eithafol [[Yr Antarctig|Antarctica]] cyfandirol.<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|archiveurl=https://web.archive.org/web/20181106225451/https://www.bas.ac.uk/about/antarctica/wildlife/land-animals/|archivedate=6 November 2018}}</ref>
== Amrywiaeth ==
[[Delwedd:BlueWhaleWithCalf.jpg|chwith|bawd|300x300px|Y [[Morfil Glas|morfil glas]] yw'r anifail mwyaf sydd erioed wedi byw; yma gwelir mam a'i phlentyn.]]
=== Maint ===
Y [[Morfil Glas|morfil glas]] (''Balaenoptera musculus'') yw'r anifail mwyaf sydd erioed wedi byw, gan bwyso hyd at 190 [[tunnell]] ac yn mesur hyd at 33.6 metr (110 tr) o hyd. Yr anifail tir mwyaf sy'n bodoli yw'r eliffant llwyni, Affricanaidd (''Loxodonta africana''), sy'n pwyso hyd at 12.25 tunnell<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> ac yn mesur hyd at 10.7 metr (35 tr) o hyd.<ref name="Wood" /> Yr anifeiliaid daearol mwyaf a fu byw erioed oedd y deinosoriaid sauropod titanosaur fel yr ''[[Argentinosaurus]]'', a allai fod wedi pwyso cymaint â 73 tunnell.<ref name="Mazzettaetal2004">{{Cite journal|last=Mazzetta|first=Gerardo V.|last2=Christiansen, Per|last3=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}}</ref> Mae sawl anifail yn feicrosgopig; nid yw rhai Myxozoa (parasitiaid gorfodol o fewn y Cnidaria) byth yn tyfu'n fwy nag 20 [[Micrometr|µm]],<ref>{{Cite web|url=http://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|archiveurl=https://web.archive.org/web/20180301225416/http://tolweb.org/Myxozoa/2460/2008.07.10|archivedate=1 March 2018}}</ref> ac nid yw'r ''Myxobolus shekel'' yn fwy na 8.5 µm pan fydd wedi tyfu'n llawn.<ref>{{Cite journal|last=Kaur|first=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>
=== Niferoedd a chynefinoedd ===
Mae’r tabl a ganlyn yn rhestru amcangyfrif o’r niferoedd o rywogaethau sy’n bodoli ar gyfer y grwpiau anifeiliaid sydd â’r niferoedd mwyaf o rywogaethau,<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=2013-08-30|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}}</ref> ynghyd â’u prif gynefinoedd (daearol, dŵr croyw, <ref name="Balian2008">{{Cite book|last=Balian|first=E. V.|last2=Lévêque|first2=C.|last3=Segers|first3=H.|first4=K.|last4=Martens|title=Freshwater Animal Diversity Assessment|url=https://books.google.com/books?id=Dw4H6DBHnAgC&pg=PA628|year=2008|publisher=Springer|isbn=978-1-4020-8259-7|page=628}}</ref> a morol),<ref name="Hogenboom2016">{{Cite web|last=Hogenboom|first=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|archiveurl=https://web.archive.org/web/20180810141811/http://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos|archivedate=10 August 2018}}</ref> a byw’n rhydd neu ffyrdd parasitig o fyw.<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> Mae'r amcangyfrifon o rywogaethau a ddangosir yma yn seiliedig ar niferoedd a ddisgrifir yn wyddonol; mae amcangyfrifon llawer mwy wedi'u cyfrifo yn seiliedig ar wahanol ddulliau o ragfynegi, a gall y rhain amrywio'n fawr. Er enghraifft, disgrifiwyd tua 25,000–27,000 o rywogaethau o nematodau, tra bod amcangyfrifon cyhoeddedig o gyfanswm nifer y rhywogaethau nematodau yn cynnwys 10,000–20,000; 500,000; 10 miliwn; a 100 miliwn.<ref name="Felder2009">{{Cite book|last=Felder|first=Darryl L.|last2=Camp|first2=David K.|title=Gulf of Mexico Origin, Waters, and Biota: Biodiversity|url=https://books.google.com/books?id=CphA8hiwaFIC&pg=RA1-PA1111|year=2009|publisher=Texas A&M University Press|isbn=978-1-60344-269-5|page=1111}}</ref> Gan ddefnyddio patrymau o fewn yr hierarchaeth dacsonomig, cyfrifwyd bod cyfanswm y rhywogaethau anifeiliaid—gan gynnwys y rhai nad ydynt wedi’u disgrifio eto—tua 7.77 miliwn yn 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|archiveurl=https://web.archive.org/web/20180701164954/https://www.sciencedaily.com/releases/2011/08/110823180459.htm|archivedate=1 July 2018}}</ref><ref name="Mora2011">{{Cite journal|last=Mora|editor-first=Georgina M.|pmid=21886479|page=e1001127|doi=10.1371/journal.pbio.1001127|date=2011-08-23|issue=8|volume=9|journal=PLOS Biology|title=How Many Species Are There on Earth and in the Ocean?|editor-last=Mace|first=Camilo|first5=Boris|last5=Worm|first4=Alastair G.B.|last4=Simpson|first3=Sina|last3=Adl|first2=Derek P.|last2=Tittensor|pmc=3160336}}</ref>
{| class="wikitable"
![[Ffylwm|Phylwm]]
!Enghraifft
!Nifer of<br /><br />Rywogaethau
!Ar y Ddaear
!Yn y Môr
!Dŵr<br>Croyw
!Byw'n<br /><br />Rhydd
![[Arfilyn|Parasitig]]
|-
|'''[[Anelid|Anelidau]]'''
|
| align="right" |17,000<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=2013-08-30|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}}<cite class="citation journal cs1" data-ve-ignore="true" id="CITEREFZhang2013">Zhang, Zhi-Qiang (30 August 2013). [https://biotaxa.org/Zootaxa/article/download/zootaxa.3703.1.3/4273 "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)"]. ''Zootaxa''. '''3703''' (1): 5. [[Adnabyddwr gwrthrychau digidol|doi]]:[[doi:10.11646/zootaxa.3703.1.3|10.11646/zootaxa.3703.1.3]]. [https://web.archive.org/web/20190424154926/https://biotaxa.org/Zootaxa/article/download/zootaxa.3703.1.3/4273 Archived] from the original on 24 April 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">2 March</span> 2018</span>.</cite></ref>
|Yes (soil)<ref name="Hogenboom2016">{{Cite web|last=Hogenboom|first=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|archiveurl=https://web.archive.org/web/20180810141811/http://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos|archivedate=10 August 2018}}<cite class="citation web cs1" data-ve-ignore="true" id="CITEREFHogenboom">Hogenboom, Melissa. [https://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos "There are only 35 kinds of animal and most are really weird"]. BBC Earth. [https://web.archive.org/web/20180810141811/http://www.bbc.co.uk/earth/story/20150325-all-animal-life-in-35-photos Archived] from the original on 10 August 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">2 March</span> 2018</span>.</cite></ref>
|Yes<ref name="Hogenboom2016" />
|1,750<ref name="Balian2008">{{Cite book|last=Balian|first=E. V.|last2=Lévêque|first2=C.|last3=Segers|first3=H.|first4=K.|last4=Martens|title=Freshwater Animal Diversity Assessment|url=https://books.google.com/books?id=Dw4H6DBHnAgC&pg=PA628|year=2008|publisher=Springer|isbn=978-1-4020-8259-7|page=628}}<cite class="citation book cs1" data-ve-ignore="true" id="CITEREFBalianLévêqueSegersMartens2008">Balian, E. V.; Lévêque, C.; Segers, H.; Martens, K. (2008). [https://books.google.com/books?id=Dw4H6DBHnAgC&pg=PA628 ''Freshwater Animal Diversity Assessment'']. Springer. p. 628. [[Rhif Llyfr Safonol Rhyngwladol|ISBN]] [[Special:BookSources/978-1-4020-8259-7|<bdi>978-1-4020-8259-7</bdi>]].</cite></ref>
|Yes
|400<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}}<cite class="citation book cs1" data-ve-ignore="true" id="CITEREFPoulin2007">[[Robert Poulin (zoologist)|Poulin, Robert]] (2007). [[iarchive:evolutionaryecol0000poul/page/6|''Evolutionary Ecology of Parasites'']]. Princeton University Press. p. [[iarchive:evolutionaryecol0000poul/page/6|6]]. [[Rhif Llyfr Safonol Rhyngwladol|ISBN]] [[Special:BookSources/978-0-691-12085-0|<bdi>978-0-691-12085-0</bdi>]].</cite></ref>
|-
|'''[[Arthropod|Arthropods]]'''
|
| align="right" |1,257,000<ref name="Zhang2013" />
|1,000,000<br /><br />(insects)<ref name="Stork2018">{{Cite journal|last=Stork|first=Nigel E.|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}} Stork notes that 1m insects have been named, making much larger predicted estimates.</ref>
|>40,000<br /><br />(Malac-<br /><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}}</ref>
|94,000<ref name="Balian2008" />
|Yes<ref name="Hogenboom2016" />
|>45,000{{Efn|Not including [[parasitoid]]s.<ref name=Poulin2007/>}}<ref name="Poulin2007" />
|-
|'''Bryozoa'''
|
| align="right" |6,000<ref name="Zhang2013" />
|
|Yes<ref name="Hogenboom2016" />
|60–80<ref name="Balian2008" />
|Yes
|
|-
|'''[[Cordog|Chordates]]'''
|
| align="right" |>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}}</ref>
|<br /><br />23,000<ref name="Reaka-Kudla1996">{{Cite book|last=Reaka-Kudla|first=Marjorie L.|last2=Wilson|first2=Don E.|last3=Wilson|first3=Edward O.|author-link3=E. O. Wilson|title=Biodiversity II: Understanding and Protecting Our Biological Resources|url=https://books.google.com/books?id=-X5OAgAAQBAJ&pg=PA90|year=1996|publisher=Joseph Henry Press|isbn=978-0-309-52075-1|page=90}}</ref>
|<br /><br />13,000<ref name="Reaka-Kudla1996" />
|18,000<ref name="Balian2008" /><br /><br />9,000<ref name="Reaka-Kudla1996" />
|Yes
|40<br /><br />(catfish)<ref>{{Cite book|last=Burton|first=Derek|last2=Burton|first2=Margaret|title=Essential Fish Biology: Diversity, Structure and Function|url=https://books.google.com/books?id=U0o4DwAAQBAJ&pg=PA281|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" />
|-
|'''[[Cnidariad|Cnidaria]]'''
|
| align="right" |16,000<ref name="Zhang2013" />
|
|Yes<ref name="Hogenboom2016" />
|Yes (few)<ref name="Hogenboom2016" />
|Yes<ref name="Hogenboom2016" />
|>1,350<br /><br />(Myxozoa)<ref name="Poulin2007" />
|-
|'''[[Echinoderm|Echinoderms]]'''
|
| align="right" |7,500<ref name="Zhang2013" />
|
|7,500<ref name="Zhang2013" />
|
|Yes<ref name="Hogenboom2016" />
|
|-
|'''[[Molwsg|Molluscs]]'''
|
| align="right" |85,000<ref name="Zhang2013" /><br /><br />107,000<ref name="Nicol1969" />
|<br /><br />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}}</ref>
|<br /><br />60,000<ref name="Nicol1969" />
|5,000<ref name="Balian2008" /><br /><br />12,000<ref name="Nicol1969" />
|Yes<ref name="Hogenboom2016" />
|>5,600<ref name="Poulin2007" />
|-
|'''[[Llyngyren gron|Nematodes]]'''
|
| align="right" |25,000<ref name="Zhang2013" />
|Yes (soil)<ref name="Hogenboom2016" />
|4,000<ref name="Felder2009">{{Cite book|last=Felder|first=Darryl L.|last2=Camp|first2=David K.|title=Gulf of Mexico Origin, Waters, and Biota: Biodiversity|url=https://books.google.com/books?id=CphA8hiwaFIC&pg=RA1-PA1111|year=2009|publisher=Texas A&M University Press|isbn=978-1-60344-269-5|page=1111}}<cite class="citation book cs1" data-ve-ignore="true" id="CITEREFFelderCamp2009">Felder, Darryl L.; Camp, David K. (2009). [https://books.google.com/books?id=CphA8hiwaFIC&pg=RA1-PA1111 ''Gulf of Mexico Origin, Waters, and Biota: Biodiversity'']. Texas A&M University Press. p. 1111. [[Rhif Llyfr Safonol Rhyngwladol|ISBN]] [[Arbennig:Ffynonellau Llyfrau/978-1-60344-269-5|<bdi>978-1-60344-269-5</bdi>]].</cite></ref>
|2,000<ref name="Balian2008" />
|11,000<ref name="Felder2009" />
|14,000<ref name="Felder2009" />
|-
|'''[[Llyngyren ledog|Platyhelminthes]]'''
|
| align="right" |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}}</ref>
|Yes<ref name="Hogenboom2016" />
|1,300<ref name="Balian2008" />
|Yes<ref name="Hogenboom2016" /><br /><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=https://books.google.com/books?id=l6rMDwAAQBAJ&pg=PT14}}</ref>
|>40,000<ref name="Poulin2007" /><br /><br />
4,000–25,000<ref name="Pandian" />
|-
|'''Rotifers'''
|
| align="right" |2,000<ref name="Zhang2013" />
|
|>400<ref>{{Cite web|last=Fontaneto|first=Diego|title=Marine Rotifers {{!}} An Unexplored World of Richness|url=http://ukmarinesac.org.uk/PDF/rotifers.pdf|publisher=JMBA Global Marine Environment|access-date=2 March 2018|pages=4–5|archiveurl=https://web.archive.org/web/20180302225409/http://ukmarinesac.org.uk/PDF/rotifers.pdf|archivedate=2 March 2018}}</ref>
|2,000<ref name="Balian2008" />
|Yes
|
|-
|'''[[Sbwng|Sponges]]'''
|
| align="right" |10,800<ref name="Zhang2013" />
|
|Yes<ref name="Hogenboom2016" />
|200-300<ref name="Balian2008" />
|Yes
|Yes<ref>{{Cite book|last=Morand|first=Serge|last2=Krasnov|first2=Boris R.|last3=Littlewood|first3=D. Timothy J.|title=Parasite Diversity and Diversification|url=https://books.google.com/books?id=o2t2BgAAQBAJ&pg=PA44|year=2015|publisher=Cambridge University Press|isbn=978-1-107-03765-6|page=44|access-date=2 March 2018}}</ref>
|-
! colspan="8" |{{Canol|Total number of described extant species {{as of|2013|lc=y}}: 1,525,728<ref name="Zhang2013"/>}}
|}
== Tarddiad esblygiadol ==
[[Delwedd:DickinsoniaCostata.jpg|chwith|bawd| ''Dickinsonia costata'' o'r biota Ediacaran (c. 635–542 miliwn o flynyddoedd [[CP|yn ôl]]) yw un o'r rhywogaethau anifeiliaid hysbys cynharaf.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249">{{Cite journal|last=Bobrovskiy|first6=Jochen J.|pages=1246–1249|pmid=30237355|doi=10.1126/science.aat7228|date=20 September 2018|issue=6408|volume=361|journal=Science|title=Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals|last6=Brocks|first=Ilya|first5=Christian|last5=Hallmann|first4=Benjamin J.|last4=Nettersheim|first3=Andrey|last3=Ivantsov|first2=Janet M.|last2=Hope|bibcode=2018Sci...361.1246B}}</ref>]]
Mae'r [[Ffosil|ffosilau]] cyntaf a allai gynrychioli anifeiliaid yn ymddangos yng nghreigiau 665-miliwn oed Ffurfiant Trezona yn [[De Awstralia|Ne Awstralia]]. [[Sbwng|Mae'n debyg mai sbyngau]] cynnar yw'r ffosilau hyn.<ref name="roseMaloof">{{Cite journal|title=Possible animal-body fossils in pre-Marinoan limestones from South Australia|last4=Samuels|last9=Simons|first8=Nan|last8=Yao|first7=Gerald R.|last7=Poirier|first6=Douglas H.|last6=Erwin|first5=Claire C.|last5=Calmet|first4=Bradley M.|first3=Robert|journal=Nature Geoscience|last3=Beach|first2=Catherine V.|last2=Rose|first=Adam C.|last=Maloof|bibcode=2010NatGe...3..653M|issue=9|doi=10.1038/ngeo934|date=17 August 2010|pages=653–659|volume=3|first9=Frederik J.}}</ref>
Mae anifeiliaid i'w cael mor bell yn ôl â'r biota Ediacaran, tua diwedd y [[Cyn-Gambriaidd]], ac efallai ychydig yn gynharach. Roedd amheuaeth ers tro a oedd y ffurfiau bywyd hyn yn cynnwys anifeiliaid,<ref>{{Cite journal|last=Shen|title=The Avalon Explosion: Evolution of Ediacara Morphospace|pmid=18174439|doi=10.1126/science.1150279|pages=81–84|issue=5859|volume=319|journal=Science|year=2008|first=Bing|first4=Michał|last4=Kowalewski|first3=Shuhai|last3=Xiao|first2=Lin|last2=Dong|bibcode=2008Sci...319...81S}}</ref><ref>{{Cite journal|title=Late Ediacaran trackways produced by bilaterian animals with paired appendages|date=1 June 2018|pmc=5990303|pmid=29881773|doi=10.1126/sciadv.aao6691|pages=eaao6691|issue=6|volume=4|journal=Science Advances|last5=Xiao|first=Zhe|first5=Shuhai|last4=Yuan|first4=Xunlai|last3=Zhou|first3=Chuanming|last2=Chen|first2=Xiang|last=Chen|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> ond mae darganfod [[Cholesterol|colesterol]] lipid anifeiliaid mewn ffosilau ''Dickinsonia'' yn cadarnhau hyn.<ref name="Bobrovskiy Hope Ivantsov Nettersheim pp. 1246–1249">{{Cite journal|last=Bobrovskiy|first6=Jochen J.|pages=1246–1249|pmid=30237355|doi=10.1126/science.aat7228|date=20 September 2018|issue=6408|volume=361|journal=Science|title=Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals|last6=Brocks|first=Ilya|first5=Christian|last5=Hallmann|first4=Benjamin J.|last4=Nettersheim|first3=Andrey|last3=Ivantsov|first2=Janet M.|last2=Hope|bibcode=2018Sci...361.1246B}}<cite class="citation journal cs1" data-ve-ignore="true" id="CITEREFBobrovskiyHopeIvantsovNettersheim2018">Bobrovskiy, Ilya; Hope, Janet M.; Ivantsov, Andrey; Nettersheim, Benjamin J.; Hallmann, Christian; Brocks, Jochen J. (20 September 2018). [[doi:10.1126/science.aat7228|"Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals"]]. ''Science''. '''361''' (6408): 1246–1249. [[Bibcode (dynodydd)|Bibcode]]:[https://ui.adsabs.harvard.edu/abs/2018Sci...361.1246B 2018Sci...361.1246B]. [[Adnabyddwr gwrthrychau digidol|doi]]:<span class="cs1-lock-free" title="Freely accessible">[[doi:10.1126/science.aat7228|10.1126/science.aat7228]]</span>. [[PubMed|PMID]] [//pubmed.ncbi.nlm.nih.gov/30237355 30237355].</cite></ref> Credir bod anifeiliaid wedi tarddu o dan amodau [[ocsigen]] isel, sy'n awgrymu eu bod yn gallu byw'n gyfan gwbl trwy resbiradaeth anaerobig, ond wrth iddynt arbenigo mewn metaboledd <u>aerobig</u> daethant yn gwbl ddibynnol ar ocsigen yn eu hamgylcheddau.<ref name="Zimorski2019">{{Cite journal|last=Zimorski|first=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>
[[Delwedd:20191203_Anomalocaris_canadensis.png|bawd| Mae ''Anomalocaris canadensis'' yn un o'r llu o rywogaethau o anifeiliaid a esblygodd yn y [[ffrwydrad Cambriaidd]], gan ddechrau tua 542 miliwn o flynyddoedd yn ôl, ac a ddarganfuwyd yng ngwâu ffosil y siâl Burgess.]]
Ymddangosodd llawer o [[Ffylwm|ffyla]] o anifeiliaid am y tro cyntaf yn y cofnodion ffosil yn y [[ffrwydrad Cambriaidd]], gan ddechrau tua 542 miliwn o flynyddoedd yn ôl, mewn gwelyau fel siâl Burgess. Ymhlith y ffyla sy'n bodoli yn y creigiau hyn mae [[Molwsg|molysgiaid]], [[Braciopod|braciopodau]], onychophorans, [[Arafsymudwr]] (y tardigrades), [[Arthropod|arthropodau]], [[Echinoderm|echinodermau]] a'r hemichordatiaid, ynghyd â nifer o ffurfiau a [[Difodiant|ddifodwyd]] megis yr ''Anomalocaris'' rheibus. Fodd bynnag, gall sydynrwydd y digwyddiad fod oherwydd fod y cofnod [[ffosil]] yn wallus, yn hytrach na bod yr holl anifeiliaid hyn wedi ymddangos ar yr un pryd.<ref>{{Cite journal|last=Maloof|first7=D. A.|doi=10.1130/B30346.1|pages=1731–1774|issue=11–12|volume=122|year=2010|journal=Geological Society of America Bulletin|title=The earliest Cambrian record of animals and ocean geochemical change|first8=M. P.|last8=Eddy|last7=Fike|first=A. C.|first6=J. A.|last6=Higgins|first5=S. A.|last5=Bowring|first4=F. O.|last4=Dudas|first3=J. L.|last3=Moore|first2=S. M.|last2=Porter|bibcode=2010GSAB..122.1731M}}</ref><ref>{{Cite web|title=New Timeline for Appearances of Skeletal Animals in Fossil Record Developed by UCSB Researchers|url=http://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|archiveurl=https://web.archive.org/web/20140903062054/http://www.ia.ucsb.edu/pa/display.aspx?pkey=2364|archivedate=3 September 2014}}</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=http://www.ijdb.ehu.es/web/paper.php?doi=14756326|access-date=28 February 2018|archive-url=https://web.archive.org/web/20180716111730/http://www.ijdb.ehu.es/web/paper.php?doi=14756326|archive-date=16 July 2018}}</ref><ref name="Royal Ontario Museum">{{Cite web|title=The Tree of Life|url=http://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|archiveurl=https://web.archive.org/web/20180216054845/http://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php|archivedate=16 February 2018|date=10 June 2011}}</ref>
== Ffylogeni ==
Mae anifeiliaid yn fonoffyletig, sy'n golygu eu bod yn deillio o hynafiad cyffredin. Mae anifeiliaid yn chwaer i'r Choanoflagellata ac maent yn ffurfio'r 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|last=Budd|first=Graham E.|last2=Jensen|first2=Sören}}</ref> Mae gan yr anifeiliaid mwyaf sylfaenol, y [[Sbwng|Porifera]], Ctenophora, [[Cnidariad|Cnidaria]], a Placozoa, gynlluniau corff sydd heb gymesuredd dwyochrog. Mae eu perthynas yn dal i fod yn destun dadl; gallai'r chwaer grŵp i bob anifail arall fod yn Porifera neu'r Ctenophora,<ref name="Kapli_2020">{{Cite journal|last=Kapli|first=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 Dec 2020|volume=6|issue=10|pages=eabc5162|doi=10.1126/sciadv.abc5162|pmid=33310849|pmc=7732190|bibcode=2020SciA....6.5162K}}</ref> sydd â diffyg genynnau hox, sy'n holl bwysig wrth ddatblygu cynllun y corff cyfan.<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}}</ref>
Mae'r goeden ffylogenetig (o'r prif linachau yn unig) yn dynodi tua sawl miliwn o flynyddoedd yn ôl ( mya ) y holltodd y llinachau.<ref>{{Cite journal|last=Peterson|title=The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records|pmid=18192191|doi=10.1098/rstb.2007.2233|pages=1435–1443|issue=1496|volume=363|journal=Philosophical Transactions of the Royal Society of London B: Biological Sciences|date=27 April 2008|first=Kevin J.|first4=Davide|last4=Pisani|first3=James G.|last3=Gehling|first2=James A.|last2=Cotton|pmc=2614224}}</ref><ref>{{Cite journal|last=Parfrey|title=Estimating the timing of early eukaryotic diversification with multigene molecular clocks|bibcode=2011PNAS..10813624P|pmid=21810989|doi=10.1073/pnas.1110633108|pages=13624–13629|issue=33|volume=108|journal=[[Proceedings of the National Academy of Sciences]]|date=16 August 2011|first=Laura Wegener|first4=Laura A.|last4=Katz|author-link4=Laura A. Katz|first3=Andrew H.|last3=Knoll|first2=Daniel J. G.|last2=Lahr|pmc=3158185}}</ref><ref>{{Cite web|title=Raising the Standard in Fossil Calibration|url=http://fossilcalibrations.org/|website=Fossil Calibration Database|access-date=3 March 2018|archiveurl=https://web.archive.org/web/20180307054141/http://fossilcalibrations.org/|archivedate=7 March 2018}}</ref><ref>{{Cite journal|last=Laumer|last7=Giribet|pmid=30373720|doi=10.7554/eLife.36278|pages=e36278|volume=2018;7|journal=eLife|title=Support for a clade of Placozoa and Cnidaria in genes with minimal compositional bias|year=2018|first7=Gonzalo|first6=John C.|first=Christopher E.|last6=Marioni|first5=Ana|last5=Riesgo|first4=Vicki B.|last4=Pearse|first3=Michael G.|last3=Hadfield|first2=Harald|last2=Gruber-Vodicka|pmc=6277202}}</ref><ref>{{Cite journal|last=Adl|last8=Berney|pmid=30257078|doi=10.1111/jeu.12691|pages=4–119|issue=1|volume=66|journal=Journal of Eukaryotic Microbiology|title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes|date=2018|first9=Matthew W.|last9=Brown|first8=Cedric|first7=Sabine|first=Sina M.|last7=Agatha|first6=Alexey|last6=Smirnov|first5=Conrad L.|last5=Schoch|first4=Julius|last4=Lukeš|first3=Christopher E.|last3=Lane|first2=David|last2=Bass|pmc=6492006}}</ref>
=== Anifeiliaid nad ydynt yn ddwyochrog ===
[[Delwedd:Elephant-ear-sponge.jpg|de|bawd| Mae rhai nad ydynt yn ddwyochrog (o ran cymesuredd) yn cynnwys [[Sbwng|sbyngau]] (canol) a [[Cwrel|chwrelau]] (cefndir).]]
Mae gan nifer o anifeiliaid ddiffyg cymesuredd dwyochrog ac ymhlith y rhain, mae'n debyg bod y sbyngau (Porifera) wedi dargyfeirio gyntaf, gan gynrychioli'r ffylwm anifail hynaf.<ref>{{Cite book|last=Bhamrah|first=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> Nid ydynt yn [[Organeb byw|organebau]] cymhleth, fel y rhan fwyaf o ffyla eraill;<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> ceir amrywiaeth yn y math o gelloedd, ond yn y rhan fwyaf o achosion nid ydynt wedi'u trefnu'n feinweoedd gwahanol.<ref>{{Cite book|last=Jessop|first=Nancy Meyer|title=Biosphere; a study of life|year=1970|publisher=[[Prentice-Hall]]|page=428}}</ref> Maent fel arfer yn bwydo trwy dynnu dŵr trwy fandyllau.<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>
=== Dwyochredd (Bilateria) ===
Mae'r anifeiliaid sy'n weddill, y mwyafrif helaeth—yn cynnwys rhyw 29 ffyla a thros filiwn o rywogaethau—yn ffurfio cytras (''clade''), sef y ''Bilateria''. Mae'r corff yn driploblastig, gyda thair haen o germ sydd wedi'u datblygu'n dda, ac mae eu meinweoedd yn ffurfio organau gwahanol. Mae gan y siambr dreulio ddau agoriad, ceg ac anws, a cheir ceudod corff mewnol, coelom neu ffug-goelom. Mae gan anifeiliaid sydd â'r cynllun dwyochrog cymesur hwn i'w corff y gallu i symud, pen blaen (''anterior''), a phen ôl (''posterior'') yn ogystal â chefn (''dorsal'') a bol (''ventral''); felly y mae ganddynt hefyd ochr dde ac ochr chwith.<ref name="Minelli2009">{{Cite book|last=Minelli|first=Alessandro|title=Perspectives in Animal Phylogeny and Evolution|url=https://books.google.com/books?id=jIASDAAAQBAJ&pg=PA53|year=2009|publisher=[[Oxford University Press]]|isbn=978-0-19-856620-5|page=53}}</ref><ref name="Brusca2016">{{Cite book|url=http://www.sinauer.com/media/wysiwyg/samples/Brusca3e_Chapter_9.pdf|title=Introduction to the Bilateria and the Phylum Xenacoelomorpha {{!}} Triploblasty and Bilateral Symmetry Provide New Avenues for Animal Radiation|last=Brusca|first=Richard C.|date=2016|publisher=[[Sinauer Associates]]|pages=345–372|isbn=978-1-60535-375-3|access-date=4 March 2018}}</ref>
Mae astudiaethau genetig wedi newid dealltwriaeth sŵolegwyr yn sylweddol o'r perthnasoedd o fewn y ''Bilateria''. Ymddengys bod y rhan fwyaf yn perthyn i ddwy brif linach, y protostomau a'r deuterostomau.<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}}</ref><ref name="Philippe2011">{{Cite journal|last=Philippe|first8=K. J.|issue=7333|bibcode=2011Natur.470..255P|doi=10.1038/nature09676|pmid=21307940|year=2011|pages=255–258|volume=470|journal=[[Nature (journal)|Nature]]|title=Acoelomorph flatworms are deuterostomes related to ''Xenoturbella''|first9=M.J.|last9=Telford|last8=Peterson|first=H.|first7=A.|last7=Wallberg|first6=A.J.|last6=Poustka|first5=H.|last5=Nakano|first4=L. L.|last4=Moroz|first3=R.R.|last3=Copley|first2=H.|last2=Brinkmann|pmc=4025995}}</ref><ref name="Perseke2007">{{Cite journal|last=Perseke|first8=M.|archive-url=https://web.archive.org/web/20190424154927/http://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf|access-date=4 March 2018|doi=10.1007/s12064-007-0007-7|pmid=18087755|url=http://www.bioinf.uni-leipzig.de/Publications/PREPRINTS/07-009.pdf|pages=35–42|date=August 2007|issue=1|volume=126|journal=Theory Biosci|title=The mitochondrial DNA of Xenoturbella bocki: genomic architecture and phylogenetic analysis|last8=Schlegel|first=M.|first7=D.|last7=Bernhard|first6=O.|last6=Israelsson|first5=P.F.|last5=Stadler|first4=G.|last4=Fritzsch|first3=B.|last3=Weich|first2=T.|last2=Hankeln|archive-date=24 April 2019}}</ref><ref name="Cannon 2016">{{Cite journal|last=Cannon|date=3 February 2016|bibcode=2016Natur.530...89C|pmid=26842059|doi=10.1038/nature16520|pages=89–93|issue=7588|volume=530|journal=[[Nature (journal)|Nature]]|title=Xenacoelomorpha is the sister group to Nephrozoa|first6=Andreas|first=Johanna T.|last6=Hejnol|first5=Ulf|last5=Jondelius|first4=Frederik|last4=Ronquist|first3=Julian.|last3=Smith III|first2=Bruno C.|last2=Vellutini|url=http://urn.kb.se/resolve?urn=urn:nbn:se:nrm:diva-1844}}</ref>
== Cyfeiriadau ==
{{cyfeiriadau}}
== Dolenni allanol ==
* [http://tolweb.org/ Prosiect Coeden Fywyd]
* [http://animaldiversity.org/ Animal Diversity Web] – cronfa ddata anifeiliaid [[Prifysgol Michigan]]
* [https://archive.today/20160426231847/http://www.arkive.org/ ARKive] – cronfa ddata amlgyfrwng o rywogaethau sydd mewn perygl/a warchodir
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[[Categori:Anifeiliaid|*]]
[[Categori:Pethau byw]]
[[Categori:Tacsa wedi'u henwi gan Carolus Linnaeus]]
[[Categori:Teyrnasoedd (bioleg)]]
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