Editing Crocodile (section)

==Characteristics==
{{Hatnote|Crocodiles are similar to alligators and caimans; for their common characteristics and differences among them, see [[Crocodilia]].}}
[[File:Skull & scutes - Crocodylinae.jpg|thumb|Skulls and scutes of [[American crocodile|American]], [[Nile crocodile|Nile]] and [[Saltwater crocodile]]s, with post-occipital scutes highlighted in red, nuchal shield in blue and dorsal scutes in green]]
[[File:Crocodilelyd5.png|thumb|Crocodiles, like dinosaurs, have the abdominal ribs modified into ''[[gastralium|gastralia]]''.]]
Apart from the advantage conferred by its sufficiently large size relative to other animals in the ecosystem,<ref>{{Cite journal|last1=Somaweera  |first1=Ruchira |last2= Brien|first2=Matthew|last3= Shine|first3=Richard|location=Australia|date=1 December 2013|url=https://meridian.allenpress.com/herpetological-monographs/article-abstract/27/1/23/33006/The-Role-of-Predation-in-Shaping-Crocodilian|title=The Role of Predation in Shaping Crocodilian Natural History|journal=[[Herpetological Monographs]]|volume=27  |issue=1|pages=Abstract|issn=0733-1347|doi=10.1655/HERPMONOGRAPHS-D-11-00001 |url-access=subscription}}</ref> other physical traits contribute a crocodile's position as [[predator]]. Its external [[morphology (biology)|morphology]] is a sign of its [[aquatic animal|aquatic]] and predatory lifestyle. Its [[Drag (physics)|streamlined]] body enables it to swim swiftly; it also tucks its feet to the side while swimming, making it faster by decreasing water resistance. Crocodiles have [[webbed feet]] which, though not used to propel them through the water, allow them to make fast turns and sudden moves in the water or initiate swimming. Webbed feet are an advantage in shallow water, where the animals sometimes move around by walking. Crocodiles have a [[palatal]] flap, a rigid tissue at the back of the mouth that blocks the entry of water. The palate has a special path from the [[nostril]] to the [[glottis]] that bypasses the mouth. The nostrils are closed during submergence.

Like other [[archosaur]]s, crocodilians are [[diapsid]], although their [[post-temporal fenestra]]e are reduced. The walls of the braincase are bony but lack supratemporal and postfrontal bones.<ref name=ausfauna>Grigg, Gordon and Gans, Carl (1993) [http://eprint.uq.edu.au/archive/00002011/02/croc.pdf Morphology And Physiology Of The Crocodylia] {{webarchive|url=https://web.archive.org/web/20050720011236/http://eprint.uq.edu.au/archive/00002011/02/croc.pdf |date=20 July 2005 }}, in Fauna of Australia Vol 2A Amphibia and Reptilia, chapter 40, pp. 326–336. Australian Government Publishing Service, Canberra.</ref> Their [[tongue]]s are not free, but held in place by a membrane that limits movement; as a result, crocodiles are unable to stick out their tongues.<ref>{{cite book | last = Huchzermeyer | first = Fritz | year = 2003 | title = Crocodiles: Biology, Husbandry and Diseases | publisher = CABI Publishing | isbn =978-0-85199-656-1 | url = https://books.google.com/books?id=4Arv-IUFnuoC| page = 13 }}</ref> Crocodiles have smooth skin on their bellies and sides, while their dorsal surfaces are armoured with large [[osteoderms]]. The armoured skin has scales and is thick and rugged, providing some protection. They are still able to absorb heat through this armour, as a network of small [[capillaries]] allows blood through the scales to absorb heat. The osteoderms are highly vascularised and aid in calcium balance, both to neutralize acids while the animal cannot breathe underwater<ref>{{Cite web|last=Wednesday|first=25 April 2012 Anna SallehABC|date=25 April 2012|title=Antacid armour key to tetrapod survival|url=http://www.abc.net.au/science/articles/2012/04/25/3488040.htm|access-date=26 July 2020|website=www.abc.net.au|language=en-AU}}</ref> and to provide calcium for eggshell formation.<ref name=":0">{{Cite journal|last1=Dacke|first1=C.|last2=Elsey|first2=R.|last3=Trosclair|first3=P.|last4=Sugiyama|first4=T.|last5=Nevarez|first5=Javier|last6=Schweitzer|first6=Mary|date=1 September 2015|title=Alligator osteoderms as a source of labile calcium for eggshell formation|url=https://www.researchgate.net/publication/280973901|journal=Journal of Zoology|volume=297|issue=4|pages=255–264|doi=10.1111/jzo.12272}}</ref> Crocodilian tegument have pores believed to be sensory in function, analogous to the [[lateral line]] in fishes. They are particularly seen on their upper and lower jaws. Another possibility is that they are secretory, as they produce an oily substance which appears to flush mud off.<ref name=ausfauna />

===Size===
[[File:Large Crocodylus porosus.jpg|thumb|230px|A [[saltwater crocodile]] in captivity]]
Size greatly varies among species, from the [[dwarf crocodile]] to the [[saltwater crocodile]]. Species of the dwarf crocodile ''Osteolaemus'' grow to an adult size of just {{convert|1.5|to|1.9|m|ft|abbr=on}},<ref>[http://crocodilian.com/cnhc/csp_otet.htm]. Crocodilian Species List. Retrieved on 14 April 2012</ref> whereas the saltwater crocodile can grow to sizes over {{convert|6|m|ft|abbr=on}} and weigh over {{convert|1000|kg|lb|abbr=on}}.<ref>Guinness Book of World Records. Retrieved on 8 April 2013.</ref> Several other large species can reach over {{convert|5.2|m|ft|abbr=on}} long and weigh over {{convert|900|kg|lb|abbr=on}}. Crocodilians show pronounced [[sexual dimorphism]], with males growing much larger and more rapidly than females.<ref name=ausfauna /> Despite their large adult sizes, crocodiles start their lives at around {{convert|20|cm|in|abbr=on}} long. The largest species of crocodile is the saltwater crocodile, found in eastern India, northern Australia, throughout [[South-east Asia]], and in the surrounding waters.

The brain volume of two adult crocodiles was 5.6&nbsp;cm<sup>3</sup> for a [[spectacled caiman]] and 8.5&nbsp;cm<sup>3</sup> for a larger [[Nile crocodile]].<ref>{{Cite journal | doi=10.1371/journal.pone.0178491| pmid=28614349| pmc=5470673|bibcode = 2017PLoSO..1278491J|title = Volume of the crocodilian brain and endocast during ontogeny| journal=PLOS ONE| volume=12| issue=6| pages=e0178491|last1 = Jirak|first1 = Daniel| last2=Janacek| first2=Jiri| year=2017| doi-access=free}}</ref>

The largest crocodile ever held in captivity is a saltwater–Siamese hybrid named Yai ({{langx|th|ใหญ่}}, meaning big; born 10 June 1972) at the [[Samutprakarn Crocodile Farm and Zoo]], [[Thailand]]. This animal measures {{convert|6|m|abbr=on}} in length and weighs {{convert|1200|kg|abbr=on}}.<ref>[http://www.worldcrocodile.com/centerfarm.swf The Guinness Book of Records. Largest Captive Crocodile] {{Webarchive|url=https://web.archive.org/web/20101105124058/http://www.worldcrocodile.com/centerfarm.swf |date=5 November 2010 }}, Worldcrocodile.com</ref>

The longest crocodile captured alive was [[Lolong]], a saltwater crocodile which was measured at {{convert|6.17|m|ft|abbr=on}} and weighed at {{convert|1075|kg|abbr=on}} by a National Geographic team in Agusan del Sur Province, Philippines.<ref>{{cite web|last=Britton|first=Adam|title=Lolong officially the world's largest crocodile in captivity|url=http://crocodilian.blogspot.com/2012/06/lolong-officially-worlds-largest.html|publisher=Crocodilian.com|access-date=12 July 2012|date=23 June 2012|archive-date=18 December 2013|archive-url=https://web.archive.org/web/20131218183151/http://crocodilian.blogspot.com/2012/06/lolong-officially-worlds-largest.html|url-status=dead}}</ref><ref>{{cite news|title=Displaced Species|url=http://www.philstar.com/Article.aspx?articleId=824855&publicationSubCategoryId=64|archive-url=https://archive.today/20130131170445/http://www.philstar.com/Article.aspx?articleId=824855&publicationSubCategoryId=64|url-status=dead|archive-date=31 January 2013|newspaper=PhilStar|access-date=12 July 2012}}</ref><ref>{{cite web|author=GMA News with Ben Serrano|author2=Paterno Esmaquel|name-list-style=amp|title=NatGeo team confirms Lolong the croc is world's longest|url=http://www.gmanews.tv/story/237992/nation/natgeo-team-confirms-lolong-the-croc-is-worlds-longest|work=GMA News Online Top Stories|date=9 November 2011 |publisher=GMA Network Inc.|access-date=15 November 2011}}</ref>

===Teeth===
Crocodiles are [[polyphyodont]]s; they are able to replace each of their 80 teeth up to 50 times in their 35- to 75-year lifespan.<ref>{{cite web|url=http://blogs.smithsonianmag.com/science/2013/05/solving-an-alligator-mystery-may-help-humans-regrow-lost-teeth/#ixzz2jeiA3qon|title=Solving an Alligator Mystery May Help Humans Regrow Lost Teeth|first=Rachel|last=Nuwer|author-link=Rachel Nuwer |access-date=4 November 2013|archive-date=25 June 2013|archive-url=https://web.archive.org/web/20130625153648/http://blogs.smithsonianmag.com/science/2013/05/solving-an-alligator-mystery-may-help-humans-regrow-lost-teeth/#ixzz2jeiA3qon|url-status=dead}}</ref><ref>{{cite journal|title=Specialized stem cell niche enables repetitive renewal of alligator teeth|first1=Ping|last1=Wu|first2=Xiaoshan|last2=Wu|first3=Ting-Xin|last3=Jiang|first4=Ruth M.|last4=Elsey|first5=Bradley L.|last5=Temple|first6=Stephen J.|last6=Divers|first7=Travis C.|last7=Glenn|first8=Kuo|last8=Yuan|first9=Min-Huey|last9=Chen|first10=Randall B.|last10=Widelitz|first11=Cheng-Ming|last11=Chuong|author-link11=Cheng-Ming Chuong|date=28 May 2013|journal=PNAS|volume=110|issue=22|pages=E2009–E2018|doi=10.1073/pnas.1213202110|pmid=23671090|pmc=3670376|bibcode=2013PNAS..110E2009W|doi-access=free}}</ref> Next to each full-grown tooth, there is a small replacement tooth and an [[Animal tooth development|odontogenic]] [[stem cell]] in the [[dental lamina]] in standby that can be activated if required.<ref>[http://www-hsc.usc.edu/~cmchuong/2013AllTooth.pdf Specialized stem cell niche enables repetitive renewal of alligator teeth] {{webarchive |url=https://web.archive.org/web/20131104212952/http://www-hsc.usc.edu/~cmchuong/2013AllTooth.pdf |date=4 November 2013 }}</ref>