\[ **BT: [[chordates#Vertebrata (Subphylum)|vertebrates]]** ] --- # reptiles ## classification of reptiles | REPTILIA | Order | Suborder | | Notes | | -------- | --------------------- | ------------------------- | --- | ------------ | | | Crocodylia | | | crocodilians | | | Sphenodontia | | | tuatara | | | [[#Squamata (Order)]] | [[#Serpentes (Suborder)]] | | snakes | | | | | | lizards | | | Testudines | | | turtles | [^1] --- ## Squamata (Order) [[Squamates are snakes and lizards.]][^2] ### hemipenes [[Hemipenes are one of the shared characteristics of squamates, distinguishing them from other reptiles.]][^3] [[The two penises of squamates (snakes and lizards) are called hemipenes; individually, each is a hemipenis.]][^4] [[In squamates, each hemipenis has its own single testis (i.e. sperm ejaculated through the right hemipenis is produced in the right testis, etc.).]][^5] [[Hemipenes are normally stored inside out in the base of the tail, forming a pocket into which a probe can be inserted to check a squamate's sex.]][^6] These organs are highly variable in morphology, with differences observed both within and between species. For example: - The hemipenes of the *Atractus* genus are particularly variable, with the primitive unicapitate hemipenal condition being widespread.[^7] - African snake hemipenes are described as simple, unornamented, and elongate structures.[^8] - In the Uropeltidae family, the hemipenes exhibit a range of morphologies, including bulbous and mushroom-shaped, simple and smooth, and simple and subcylindrical with fine spines.[^9] [[Snakes only use one hemipene at a time.]][^10] --- ### Serpentes (Suborder) [[The snake has always been viewed with some ambivalence; ‘it is a creature crawling on the earth that also suggests rebirth in its ability to shed its skin and be revitalized every spring.’]][^11] - see also: [[folklore#snakes]] #### snake hearing [[Snakes do not have ears. They do, however, react to both (loud) airborne sounds and ground-based vibrations. This is called somatic hearing.]][^12] #### snake reproduction [[Female snakes can store sperm for up to 5 years (and possibly longer).]][^13] ***Female choice of sperm:*** [[If a female snake has mated with multiple males, her clutch or litter can be a mixture of offspring from multiple fathers. Furthermore, she can control which fathers' sperm she uses to fertilise her eggs.]][^14] --- ### Colubridae (Family) #### Natricinae (Subfamily) ##### *Thamnophis* (Genus) Garter snake is the common name for small to medium-sized snakes belonging to the genus Thamnophis in the family Colubridae. They are native to North and Central America, ranging from central Canada in the north to Costa Rica in the south.[^15] [[Garter snake mating often occurs in large balls of males attempting to copulate with a single focal snake; sometimes this is a receptive female, sometimes it is a male snake releasing similar receptive pheromones.]][^16] ###### *Thamnophis sirtalis parietalis* (Red-sided garter snake) ## endnotes [^1]: ‘List of reptiles’, Wikipedia, last edited 7 October 2025, 08:40 (UTC), https://en.wikipedia.org/wiki/List_of_reptiles. [^2]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^3]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^4]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^5]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^6]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^7]: Walter E. Schargel and Todd A. Castoe, ‘The Hemipenes of Some Snakes of the Semifossorial Genus Atractus, with Comments on Variation in the Genus’, *Journal of Herpetology*, vol. 37, no. 4, (2003), pp. 718–21, [https://doi.org/10.1670/7-02N](https://doi.org/10.1670/7-02N). [^8]: W. R. Branch, ‘Hemipenial Morphology of African Snakes: A Taxonomic Review. Part 1. Scolecophidia and Boidae’, *Journal of Herpetology*, vol. 20, no. 3 (1986), pp. 285–99, https://doi.org/10.2307/1564495. [^9]: Alexander R. Pyron et al., ‘First Report of Hemipenial Variation among Some Genera and Species of Shieldtail Snakes (Serpentes: Uropeltidae) from India and Sri Lanka’, *Ichthyology & Herpetology*, vol. 110, no. 2 (2022), pp. 299–314, https://doi.org/10.1643/h2021024. [^10]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^11]: Denise Chao, ‘[[Chao, ‘The Snake in Chinese Belief’, 1979|The Snake in Chinese Belief]]’, *Folklore*, vol. 90, no. 2 (1979), p. 193, [https://doi.org/10.1080/0015587X.1979.9716142](https://doi.org/10.1080/0015587X.1979.9716142). [^12]: Bruce A. Young, ‘[[Young, ‘Snake Bioacoustics’, 2003|Snake Bioacoustics: Toward a Richer Understanding of the Behavioral Ecology of Snakes]]’, *The Quarterly Review of Biology*, vol 78, no. 3 (2003), p. 303, https://doi.org/10.1086/377052; C. B. Christensen et al., ‘[[Christensen et al. ‘Hearing with an Atympanic Ear’, 2012|Hearing With an Atympanic Ear: Good Vibration and Poor Sound-Pressure Detection in the Royal Python, Python regius]]’, *Journal of Experimental Biology*, vol. 215, no. 2 (2012), p. 331, https://doi.org/10.1242/jeb.062539. [^13]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^14]: Andrew Durso, ‘[[Durso, ‘Why Do Snakes Have Two Penises_’, 2014|Why Do Snakes Have Two Penises?]]’, *Life Is Short But Snakes Are Long*, 19 March 2014, https://snakesarelong.blogspot.com/2014/03/why-do-snakes-have-two-penises.html. [^15]: ‘Garter snake’, Wikipedia, last edited 29 September 2025, 04:15 (UTC), https://en.wikipedia.org/wiki/Garter_snake. [^16]: Julia D. Monk et al., ‘[[Monk et al, ‘An Alternative Hypothesis for the Evolution of Same-Sex Sexual Behaviour in Animals’, 2019|An Alternative Hypothesis for the Evolution of Same-Sex Sexual Behaviour in Animals]]’, *Nature Ecology & Evolution*, vol. 3, no. 2 (2019), p. 1625, https://doi.org/10.1038/s41559-019-1019-7.