Editing Snake (section)

=== Reproduction ===
{{See also|Sexual selection in scaled reptiles}}
[[File:Boa and python.JPG|thumb|''[[Boa imperator]]'' (left) and an [[Albinism|albino]] ''[[Indian python|Python molurus]]'' (right). The former gives birth to live young, while the latter lays eggs.]]
Although a wide range of reproductive modes are used by snakes, all employ [[internal fertilization]]. This is accomplished by means of paired, forked [[hemipenis|hemipenes]], which are stored, inverted, in the male's tail.<ref name="Capula89_117">Capula (1989), p. 117.</ref> The hemipenes are often grooved, hooked, or spined—designed to grip the walls of the female's [[cloaca]].<ref name="AldridgeSever2016">{{cite book |first1=Robert D. |last1=Aldridge |first2=David M. |last2=Sever |name-list-style=vanc |title=Reproductive Biology and Phylogeny of Snakes |url=https://books.google.com/books?id=u-3RBQAAQBAJ |date=April 19, 2016 |publisher=[[CRC Press]] |isbn=978-1-4398-5833-2 |via=[[Google Books]]}}</ref><ref name="Capula89_117"/> The [[Hemipenis#Hemiclitoris|clitoris of the female snake]] consists of two structures located between the cloaca and the scent glands.<ref name="hemic">{{cite journal |last1=Fowell |first1=Megan J. |last2=Sanders |first2=Kate L. |last3=Brennan |first3=Patricia L. R. |last4=Crowe-Riddell |first4=Jenna M. |title=First evidence of hemiclitores in snakes |journal=[[Proceedings of the Royal Society B]] |date=December 21, 2022 |volume=289 |issue=1989 |doi=10.1098/rspb.2022.1702 |pmid=36515117 |pmc=9748774}}</ref>

Most species of snakes lay [[egg (biology)|eggs]] which they abandon shortly after laying. However, a few species (such as the king cobra) construct nests and stay in the vicinity of the hatchlings after incubation.<ref name="Capula89_117"/> Most pythons coil around their egg-clutches and remain with them until they hatch.{{sfn|Cogger|Zweifel|1992|p=186}} A female python will not leave the eggs, except to occasionally bask in the sun or drink water. She will even "shiver" to generate heat to incubate the eggs.{{sfn|Cogger|Zweifel|1992|p=186}}

Some species of snake are [[Ovoviviparity|ovoviviparous]] and retain the eggs within their bodies until they are almost ready to hatch.<ref name="Capula89_118">Capula (1989), p. 118.</ref>{{sfn|Cogger|Zweifel|1992|p=182}} Several species of snake, such as the [[boa constrictor]] and green anaconda, are fully [[Viviparity|viviparous]], nourishing their young through a [[placenta]] as well as a [[yolk sac]]; this is highly unusual among reptiles, and normally found in [[requiem sharks]] or [[placental mammals]].<ref name="Capula89_118"/>{{sfn|Cogger|Zweifel|1992|p=182}} Retention of eggs and live birth are most often associated with colder environments.<ref name="Capula89_117"/>{{sfn|Cogger|Zweifel|1992|p=182}}

[[File:Coast Garter Snake.jpg|thumb|right|The [[garter snake]] has been studied for sexual selection.]]
[[Sexual selection]] in snakes is demonstrated by the 3,000 species that each use different tactics in acquiring mates.<ref name="two">{{cite journal |doi=10.1016/j.anbehav.2003.05.007 |title=Courtship tactics in garter snakes: How do a male's morphology and behaviour influence his mating success? |year=2004 |last1=Shine |first1=Richard |last2=Langkilde |first2=Tracy |last3=Mason |first3=Robert T |name-list-style=vanc |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=67 |issue=3 |pages=477–83 |s2cid=4830666}}</ref> Ritual combat between males for the females they want to [[mating|mate]] with includes topping, a behavior exhibited by most viperids in which one male will twist around the vertically elevated fore body of its opponent and force it downward. It is common for neck-biting to occur while the snakes are entwined.<ref name="three">{{cite journal |doi=10.1016/j.anbehav.2004.03.012 |title=Genetic evidence for sexual selection in black ratsnakes, ''Elaphe obsoleta'' |year=2005 |last1=Blouin-Demers |first1=Gabriel |last2=Gibbs |first2=H. Lisle |last3=Weatherhead |first3=Patrick J. |name-list-style=vanc |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=69 |issue=1 |pages=225–34 |s2cid=3907523}}</ref>