Editing Snake (section)

=== Skin ===
{{Main|Snake scale}}
The skin of a snake is covered in [[Scale (anatomy)|scales]]. Contrary to the popular notion of snakes being slimy (because of possible confusion of snakes with [[worm]]s), [[snakeskin]] has a smooth, dry texture. Most snakes use specialized belly scales to travel, allowing them to grip surfaces. The body scales may be smooth, [[keeled scales|keeled]], or granular. The eyelids of a snake are transparent "spectacle" scales, also known as [[brille]], which remain permanently closed.{{Citation needed|date=November 2024}}

For a snake, the skin has been modified to its specialized form of locomotion. Between the inner layer and the outer layer lies the dermis, which contains all the pigments and cells that make up the snake's distinguishing pattern and color. The epidermis, or outer layer, is formed of a substance called [[keratin]], which in mammals is the same basic material that forms nails, claws, and hair. The snake's epidermis of keratin provides it with the armor it needs to protect its internal organs and reduce friction as it passes over rocks. Parts of this keratin armor are rougher than others. The less restricted portion overlaps the front of the scale beneath it. Between them lies a folded back connecting material, also of keratin, also part of the epidermis. This folded back material gives as the snake undulates or eats things bigger than the circumference of its body.{{sfn|Campbell|Shaw|1974}}{{page needed|date=April 2024}}

The shedding of scales is called ''[[ecdysis]]'' (or in normal usage, ''molting'' or ''sloughing''). Snakes shed the complete outer layer of skin in one piece.<ref name = "Smith1_30">Smith, Malcolm A. ''[[The Fauna of British India, Including Ceylon and Burma]]''. Vol I, Loricata and Testudines. p. 30.</ref> Snake scales are not discrete, but extensions of the [[epidermis]]—hence they are not shed separately but as a complete outer layer during each molt, akin to a sock being turned inside out.<ref name="RSSlimy">{{cite web|url=http://www.szgdocent.org/resource/rr/c-slimy.htm |title=Are Snakes Slimy? |website=szgdocent.org |archive-url=https://web.archive.org/web/20060805131135/http://www.szgdocent.org/resource/rr/c-slimy.htm |archive-date=5 August 2006 |url-status=live}}</ref>

Snakes have a wide diversity of skin coloration patterns which are often related to behavior, such as the tendency to have to flee from predators. Snakes that are at a high risk of predation tend to be plain, or have longitudinal stripes, providing few reference points to predators, thus allowing the snake to escape without being noticed. Plain snakes usually adopt active hunting strategies, as their pattern allows them to send little information to prey about motion. Blotched snakes usually use ambush-based strategies, likely because it helps them blend into an environment with irregularly shaped objects, like sticks or rocks. Spotted patterning can similarly help snakes to blend into their environment.<ref name="AllenBaddeley2013">{{cite journal |last1=Allen |first1=William L. |last2=Baddeley |first2=Roland |last3=Scott-Samuel |first3=Nicholas E. |last4=Cuthill |first4=Innes C. |name-list-style=vanc |title=The evolution and function of pattern diversity in snakes |journal=[[Behavioral Ecology (journal)|Behavioral Ecology]] |volume=24 |issue=5 |year=2013 |pages=1237–1250 |issn=1465-7279 |doi=10.1093/beheco/art058 |doi-access=free}}</ref>

The shape and number of scales on the head, back, and belly are often characteristic and used for taxonomic purposes. Scales are named mainly according to their positions on the body. In "advanced" ([[Caenophidia]]n) snakes, the broad belly scales and rows of [[dorsal scale]]s correspond to the [[vertebra]]e, allowing these to be counted without the need for [[dissection]].{{Citation needed|date=November 2024}}

==== Molting ====
[[File:Nerodia sipedon shedding.JPG|thumb|left|A [[common watersnake]] shedding its skin]]
[[Molting]] (or "ecdysis") serves a number of purposes - it allows old, worn skin to be replaced and can be synced to mating cycles, as with other animals. Molting occurs periodically throughout the life of a snake. Before each molt, the snake regulates its diet and seeks defensible shelter. Just before shedding, the skin becomes grey and the snake's eyes turn silvery. The inner surface of the old skin liquefies, causing it to separate from the new skin beneath it. After a few days, the eyes clear and the snake reaches out of its old skin, which splits. The snake rubs its body against rough surfaces to aid in the shedding of its old skin. In many cases, the castaway skin peels backward over the body from head to tail in one piece, like taking the dust jacket off a book, revealing a new, larger, brighter layer of skin which has formed underneath.<ref name="RSSlimy"/><ref name="GenSnakeInfo">{{cite web|url=http://www.sdgfp.info/Wildlife/Snakes/SnakeInfo.htm |title=General Snake Information |website=sdgfp.info |archive-url=https://web.archive.org/web/20071125210255/http://www.sdgfp.info/Wildlife/Snakes/SnakeInfo.htm |archive-date=November 25, 2007 |url-status=dead}}</ref> Renewal of the skin by molting supposedly increases the mass of some animals such as insects, but in the case of snakes this has been disputed.<ref name="RSSlimy"/><ref name="ZooPax3">{{cite web |url=http://whozoo.org/ZooPax/ZPScales_3.htm |title=ZooPax: A Matter of Scale: Part III |website=Whozoo.org |access-date=January 9, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160116034245/http://whozoo.org/ZooPax/ZPScales_3.htm |archive-date=January 16, 2016}}</ref> Shedding skin can release pheromones and revitalize color and patterns of the skin to increase attraction of mates.<ref>{{Cite journal |last1=Bauwens |first1=Dirk |last2=Van Damme |first2=Raoul |last3=Verheyen |first3=Rudolf F. |date=1989 |title=Synchronization of Spring Molting with the Onset of Mating Behavior in Male Lizards, Lacerta vivipara |url=https://www.jstor.org/stable/1564326 |journal=[[Journal of Herpetology]] |volume=23 |issue=1 |pages=89–91 |doi=10.2307/1564326 |jstor=1564326 |issn=0022-1511 |access-date=29 April 2022 }}</ref>

Snakes may shed four of five times a year, depending on the weather conditions, food supply, age of the snake, and other factors.{{sfn|Campbell|Shaw|1974}}{{page needed|date=April 2024}}<ref name = "GenSnakeInfo"/> It is theoretically possible to identify the snake from its cast skin if it is reasonably intact.<ref name="RSSlimy"/> Mythological associations of snakes with symbols of [[healing]] and [[medicine]], as pictured in the [[Rod of Asclepius]], are derivative of molting.<ref name=AIM>{{cite journal |vauthors=Wilcox RA, Whitham EM |title=The symbol of modern medicine: why one snake is more than two |journal=Annals of Internal Medicine |volume=138 |issue=8 |pages=673–7 |date=April 2003 |pmid=12693891 |doi=10.7326/0003-4819-138-8-200304150-00016 |citeseerx=10.1.1.731.8485 |s2cid=19125435}}</ref>

One can attempt to identify the sex of a snake when the species is not distinctly [[Sexual dimorphism|sexually dimorphic]] by counting scales. The [[cloaca]] is probed and measured against the [[subcaudal scales]].<ref name="Rosenfeld_11">Rosenfeld (1989), p. 11.</ref> Counting scales determines whether a snake is a male or female, as the [[Hemipenis|hemipenes]] of a male being probed is usually longer.<ref name="Rosenfeld_11"/>{{clarify|reason=Is it really scale counts or are the scales merely used to measure the probe penetration?|date=July 2016}}