Editing Crocodile (section)

===Senses===
[[File:A crocodiles eye (7825799462).jpg|thumb|Crocodile eye]]
Crocodiles have acute senses, an evolutionary advantage that makes them successful predators. The eyes, ears and nostrils are located on top of the head, allowing the crocodile to lie low in the water, almost totally submerged and hidden from prey.

====Vision====
Crocodiles have very good night vision, and are mostly [[Nocturnality|nocturnal]] hunters. They use the disadvantage of most prey animals' poor nocturnal vision to their advantage. The light receptors in crocodilians' eyes include [[Cone cell|cones]] and numerous [[Rod cells|rods]], so it is assumed all crocodilians can see colours.<ref>{{cite web|url=http://wikis.evergreen.edu/m2o1112/index.php/Reptiles|title=Reptiles|author=evergreen|access-date=29 April 2013|archive-url=https://web.archive.org/web/20130615152003/http://wikis.evergreen.edu/m2o1112/index.php/Reptiles|archive-date=15 June 2013|url-status=dead}}</ref> Crocodiles have vertical-slit shaped pupils, similar to those of domestic cats. One explanation for the evolution of slit pupils is that they exclude light more effectively than a circular pupil, helping to protect the eyes during daylight.<ref name="Land, (2006)">{{cite journal | last1 = Land | first1 = M.F. | year = 2006 | title = Visual optics: the shapes of pupils | journal = Current Biology | volume = 16 | issue = 5| pages = R167–R168 | doi=10.1016/j.cub.2006.02.046 | pmid=16527734| doi-access = free | bibcode = 2006CBio...16.R167L }}</ref> On the rear wall of the eye is a [[tapetum lucidum]], which reflects incoming light back onto the retina, thus utilizing the small amount of light available at night to best advantage. In addition to the protection of the upper and lower eyelids, crocodiles have a [[nictitating membrane]] (sometimes called a "third eye-lid") that can be drawn over the eye from the inner corner while the lids are open. The eyeball surface is thus protected under the water while a certain degree of vision is still possible.<ref name="Encyclopædia Britannica">{{cite web|url=https://www.britannica.com/EBchecked/topic/143679/crocodile/38424/Form-and-function|title=Crocodile|author=Encyclopædia Britannica|access-date=29 April 2013}}</ref>

====Olfaction====
Crocodilian [[Olfaction|sense of smell]] is also very well developed, aiding them to detect prey or animal carcasses that are either on land or in water, from far away. It is possible that crocodiles use olfaction in the egg prior to hatching.<ref name="Encyclopædia Britannica" />

[[Chemoreception]] in crocodiles is especially interesting because they hunt in both terrestrial and aquatic surroundings. Crocodiles have only one olfactory chamber and the [[vomeronasal organ]] is absent in the adults<ref>{{cite journal | last1 = Hansen | first1 = A | year = 2007 | title = Olfactory and solitary chemosensory cells: two different chemosensory systems in the nasal cavity of the American alligator, Alligator mississippiensis | journal = BMC Neuroscience | volume = 8 | page = 64 | doi = 10.1186/1471-2202-8-64 | pmid = 17683564 | pmc = 1950884 | doi-access = free }}</ref> indicating all olfactory perception is limited to the olfactory system. Behavioural and olfactometer experiments indicate that crocodiles detect both air-borne and water-soluble chemicals and use their olfactory system for hunting. When above water, crocodiles enhance their ability to detect volatile odorants by gular pumping, a rhythmic movement of the floor of the pharynx.<ref>{{cite journal | last1 = Gans | first1 = C. | last2 = Clark | first2 = B. | year = 1976 | title = Studies on ventilation of Caiman crocodilus (Crocodilia: Reptilia) | url =https://deepblue.lib.umich.edu/bitstream/2027.42/21779/1/0000173.pdf | journal = Respir. Physiol | volume = 26 | issue = 3| pages = 285–301 | doi=10.1016/0034-5687(76)90001-3| pmid = 951534 | hdl = 2027.42/21779 | hdl-access = free }}</ref><ref>{{cite journal | last1 = Putterill | first1 = J.F. | last2 = Soley | first2 = J.T. | year = 2006 | title = Morphology of the gular valve of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768) | journal = J. Morphol. | volume = 267 | issue = 8| pages = 924–939 | doi=10.1002/jmor.10448| pmid = 16634086 | s2cid = 21995436 }}</ref> Crocodiles close their nostrils when submerged, so olfaction underwater is unlikely. Underwater food detection is presumably gustatory and tactile.<ref>Schwenk, K. (2008). Comparative anatomy and physiology of chemical senses in nonavian aquatic reptiles. In, ''Sensory Evolution on the Threshold: Adaptations in Secondarily Aquatic Vertebrates''. J.G.M [[Hans Thewissen|Thewissen]] and S. Nummels (Eds). University of California Press, Berkeley. pp. 65–81</ref>

====Hearing====
Crocodiles can hear well; their [[Eardrum|tympanic membranes]] are concealed by flat flaps that may be raised or lowered by muscles.<ref name=ausfauna />

====Touch====
The touch sensors, concentrated in crocodile skin, can be thicker than those in human fingerprints.<ref>{{Cite web|date=9 November 2012|title=Croc Jaws More Sensitive Than Human Fingertips|url=https://www.nationalgeographic.com/animals/article/121108-nile-crocodile-duncan-leitch-science-human-sensitive-touch|archive-url=https://web.archive.org/web/20210325143141/https://www.nationalgeographic.com/animals/article/121108-nile-crocodile-duncan-leitch-science-human-sensitive-touch|url-status=dead|archive-date=25 March 2021|access-date=31 January 2022|website=Animals|language=en}}</ref> Crocodiles can feel the touch on their skin.<ref>{{Cite web|date=14 October 2021|title=Do Crocodiles Feel Pain? (Surprising Answer) {{!}}|url=https://wildexplained.com/do-crocodiles-feel-pain/|access-date=31 January 2022|language=en-us}}</ref>

'''Cranial''': The upper and lower jaws are covered with sensory pits, visible as small, black speckles on the skin, the crocodilian version of the [[lateral line]] organs seen in fish and many amphibians, though arising from a completely different origin. These pigmented nodules encase bundles of [[Axon|nerve fibers]] innervated beneath by branches of the trigeminal nerve. They respond to the slightest disturbance in surface water, detecting vibrations and small pressure changes as small as a single drop.<ref>{{cite news|url=https://www.cbc.ca/news/science/alligators-detect-silent-ripples-when-hunting-1.320458|title=Alligators detect silent ripples when hunting|author=CBCnews|year=2002|access-date=29 April 2013|work=CBC News}}</ref> This makes it possible for crocodiles to detect prey, danger and intruders, even in total darkness. These sense organs are known as domed pressure receptors (DPRs).<ref name="Jackson and Brooks">{{cite journal | last1 = Jackson | first1 = K. | last2 = Brooks | first2 = D.R. | year = 2007 | title = Do crocodiles co-opt their sense of "touch" to "taste"? A possible new type of vertebrate sensory organ | url = http://people.whitman.edu/~jacksok/AMRE2447.pdf | journal = Amphibia-Reptilia | volume = 28 | issue = 2 | pages = 277–285 | doi = 10.1163/156853807780202486 | access-date = 29 April 2013 | archive-url = https://web.archive.org/web/20130730091857/http://people.whitman.edu/~jacksok/AMRE2447.pdf | archive-date = 30 July 2013 | url-status = dead }}</ref>

'''Post-Cranial''': While alligators and caimans have DPRs only on their jaws, crocodiles have similar organs on almost every scale on their bodies. The function of the DPRs on the jaws is clear; to catch prey, but it is still not clear what the function is of the organs on the rest of the body. The receptors flatten when exposed to increased osmotic pressure, such as that experienced when swimming in sea water [[hyperosmotic]] to the body fluids. When contact between the integument and the surrounding sea water solution is blocked, crocodiles are found to lose their ability to discriminate salinities. It has been proposed that the flattening of the sensory organ in hyperosmotic sea water is sensed by the animal as "touch", but interpreted as chemical information about its surroundings.<ref name="Jackson and Brooks" /> This might be why in alligators they are absent on the rest of the body.<ref>{{cite web|url=http://crocodilian.com/cnhc/cbd-gb1.htm |title=Crocodilian Biology Database – Integumentary Sense Organs |publisher=Crocodilian.com |access-date=26 April 2013}}</ref>