The Garter snake is a Colubrid snake genus (Thamnophis) common across North America, ranging from Alaska and Canada to Central America. It is the single most widely distributed genus of reptile in North America[citation needed]. The garter snake is also the Massachusetts state reptile.[1]
There is no real consensus on the classification of species of Thamnophis. Disagreement among taxonomists and sources, such as field guides, over whether two types of snakes are separate species or subspecies of the same species is common. They are also closely related to the snakes of the genus Nerodia, and some species have been moved back and forth between genera.
Habitat
Garter snakes are widespread throughout North America. The common garter snake (Thamnophis sirtalis), is the only species of snake to be found in Alaska, and is one of the northernmost species of snake in the world, possibly second only to the Crossed Viper, Vipera berus. The genus is so far ranging due to its unparticular diet and adaptability to different biomes and landforms, with varying proximity to water. However, in the western part of North America, these snakes are more water loving than in the eastern portion. Northern populations hibernate in larger groups than southern ones.
Venom
Garters were long thought to be nonvenomous, but recent discoveries have revealed that they do in fact produce a mild neurotoxic venom.[3] Garter snakes cannot kill humans with the small amounts of venom they produce, which is comparatively mild, and they also lack an effective means of delivering it. They do have enlarged teeth in the back of their mouth, but their gums are significantly larger.[4][5] Whereas most venomous snakes have anterior or forward venom glands, the Duvernoy's gland of garters are posterior (to the rear) of the snake's eyes.[6] The mild venom is spread into wounds through a chewing action. The properties of the venom are not well known, but it appears to contain 3FTx, commonly known as three-finger toxin, which is a neurotoxin commonly found in the venom of colubrids and elapids. A bite may result in mild swelling and an itching sensation. There are no known cases of serious injury and extremely few with symptoms of envenomation.
Reproduction
Garter snakes go into brumation before they mate. They stop eating for about two weeks beforehand to clear their stomach of any food that would rot there otherwise. Garter snakes begin mating as soon as they emerge from brumation. During mating season, the males mate with several females. In chillier parts of their range, male common garter snakes awaken from brumation first, giving themselves enough time to prepare to mate with females when they finally appear. Males come out of their dens and, as soon as the females begin coming out, surround them. Female garter snakes produce a sex-specific pheromone that attracts male snakes in droves, sometimes leading to intense male-male competition and the formation of mating balls of up to 25 males per female. After copulation, a female leaves the den/mating area to find food and a place to give birth. Female garter snakes are able to store the male's sperm for years before fertilization. The young are incubated in the lower abdomen, at about the midpoint of the length of the mother's body. Garter snakes are ovoviviparous meaning they give birth to live young. However, this is different than being truly viviparous, which is seen in mammals. Gestation is two to three months in most species. As few as 3 or as many as 80 snakes are born in a single litter. The young are independent upon birth. On record, the greatest number of garter snakes to be born in a single litter is 98.
Diet
A Garter snake eating a frog
Garter snakes, like all snakes, are carnivorous. Their diet consists of almost any creature that they are capable of overpowering: slugs, earthworms, leeches, lizards, amphibians, birds, fish, toads and rodents. When living near the water, they will eat other aquatic animals. The ribbon snake (Thamnophis sauritus) in particular favors frogs (including tadpoles), readily eating them despite their strong chemical defenses. Food is swallowed whole. Garter snakes often adapt to eating whatever they can find, and whenever, because food can be scarce or abundant. Although they feed mostly upon live animals, they will sometimes eat eggs.
Taxonomy
There is no real consensus on the classification of species of Thamnophis. Disagreement among taxonomists and sources, such as field guides, over whether two types of snakes are separate species or subspecies of the same species is common. They are also closely related to the snakes of the genus Nerodia, and some species have been moved back and forth between genera.
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| Coast garter snake |
Garter snakes are widespread throughout North America. The common garter snake (Thamnophis sirtalis), is the only species of snake to be found in Alaska, and is one of the northernmost species of snake in the world, possibly second only to the Crossed Viper, Vipera berus. The genus is so far ranging due to its unparticular diet and adaptability to different biomes and landforms, with varying proximity to water. However, in the western part of North America, these snakes are more water loving than in the eastern portion. Northern populations hibernate in larger groups than southern ones.
Venom
Garters were long thought to be nonvenomous, but recent discoveries have revealed that they do in fact produce a mild neurotoxic venom.[3] Garter snakes cannot kill humans with the small amounts of venom they produce, which is comparatively mild, and they also lack an effective means of delivering it. They do have enlarged teeth in the back of their mouth, but their gums are significantly larger.[4][5] Whereas most venomous snakes have anterior or forward venom glands, the Duvernoy's gland of garters are posterior (to the rear) of the snake's eyes.[6] The mild venom is spread into wounds through a chewing action. The properties of the venom are not well known, but it appears to contain 3FTx, commonly known as three-finger toxin, which is a neurotoxin commonly found in the venom of colubrids and elapids. A bite may result in mild swelling and an itching sensation. There are no known cases of serious injury and extremely few with symptoms of envenomation.
Reproduction
Garter snakes go into brumation before they mate. They stop eating for about two weeks beforehand to clear their stomach of any food that would rot there otherwise. Garter snakes begin mating as soon as they emerge from brumation. During mating season, the males mate with several females. In chillier parts of their range, male common garter snakes awaken from brumation first, giving themselves enough time to prepare to mate with females when they finally appear. Males come out of their dens and, as soon as the females begin coming out, surround them. Female garter snakes produce a sex-specific pheromone that attracts male snakes in droves, sometimes leading to intense male-male competition and the formation of mating balls of up to 25 males per female. After copulation, a female leaves the den/mating area to find food and a place to give birth. Female garter snakes are able to store the male's sperm for years before fertilization. The young are incubated in the lower abdomen, at about the midpoint of the length of the mother's body. Garter snakes are ovoviviparous meaning they give birth to live young. However, this is different than being truly viviparous, which is seen in mammals. Gestation is two to three months in most species. As few as 3 or as many as 80 snakes are born in a single litter. The young are independent upon birth. On record, the greatest number of garter snakes to be born in a single litter is 98.
Diet
A Garter snake eating a frog
Garter snakes, like all snakes, are carnivorous. Their diet consists of almost any creature that they are capable of overpowering: slugs, earthworms, leeches, lizards, amphibians, birds, fish, toads and rodents. When living near the water, they will eat other aquatic animals. The ribbon snake (Thamnophis sauritus) in particular favors frogs (including tadpoles), readily eating them despite their strong chemical defenses. Food is swallowed whole. Garter snakes often adapt to eating whatever they can find, and whenever, because food can be scarce or abundant. Although they feed mostly upon live animals, they will sometimes eat eggs.
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| Common Garter Snake, Thamnophis sirtalis |
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| A garter snake. |
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| Common Garter Snake |
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| The posterior tooth of a garter snake |
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| Eastern Blackneck Garter, Thamnophis cyrtopsis ocellatus |
Taxonomy
- Eastern Blackneck Garter, Thamnophis cyrtopsis ocellatus
- Longnose Garter Snake, Thamnophis angustirostris (Kennicott, 1860)
- Aquatic Garter Snake, Thamnophis atratus
- Santa Cruz Garter Snake, Thamnophis atratus atratus (Kennicott, 1860)
- Oregon Garter Snake, Thamnophis atratus hydrophilus (Fitch, 1936)
- Diablo Range Garter Snake, Thamnophis atratus zaxanthus (Boundy, 1999)
- Shorthead Garter Snake, Thamnophis brachystoma (Cope, 1892)
- Butler's Garter Snake, Thamnophis butleri (Cope, 1889)
- Goldenhead Garter Snake, Thamnophis chrysocephalus (Cope, 1885)
- Western Aquatic Garter Snake, Thamnophis couchii (Kennicott, 1859)
- Blackneck Garter Snake, Thamnophis cyrtopsis
- Western Blackneck Garter Snake, Thamnophis cyrtopsis cyrtopsis (Kennicott, 1860)
- Eastern Blackneck Garter Snake, Thamnophis cyrtopsis ocellatus (Cope, 1880)
- Tropical Blackneck Garter Snake, Thamnophis cyrtopsis collaris (Jan, 1863)
- Tepalcatepec Valley Garter Snake, Thamnophis cyrtopsis postremus (Smith, 1942)
- Yellow-throated Garter Snake, Thamnophis cyrtopsis pulchrilatus (Cope, 1885)
- Checkered Garter Snake, Thamnophis marcianus
- Western Terrestrial Garter Snake, Thamnophis elegans
- Arizona Garter Snake, Thamnophis elegans arizonae (Tanner & Lowe, 1989)
- Mountain Garter Snake, Thamnophis elegans elegans (Baird & Girard, 1853)
- Mexican Wandering Garter Snake, Thamnophis elegans errans (Smith, 1942)
- Coast Garter Snake, Thamnophis elegans terrestris (Fox, 1951)
- Wandering Garter Snake, Thamnophis elegans vagrans (Baird & Girard, 1853)
- Upper Basin Garter Snake, Thamnophis elegans vascotanneri (Tanner & Lowe, 1989)
- Sierra San Pedro Mártir Garter Snake, Thamnophis elegans hueyi (Van Denburgh & Slevin, 1923)
- Thamnophis eques
- Mexican Garter Snake, Thamnophis eques eques (Reuss, 1834)
- Laguna Totolcingo Garter Snake, Thamnophis eques carmenensis (Conant, 2003)
- Thamnophis eques cuitzeoensis (Conant, 2003)
- Thamnophis eques diluvialis (Conant, 2003)
- Thamnophis eques insperatus (Conant, 2003)
- Northern Mexican Garter Snake, Thamnophis eques megalops (Kennicott, 1860)
- Thamnophis eques obscurus (Conant, 2003)
- Thamnophis eques patzcuaroensis (Conant, 2003)
- Thamnophis eques scotti (Conant, 2003)
- Thamnophis eques virgatenuis (Conant, 1963)
- Eastern Plains Garter Snake, Thamnophis radix radix, a disputed subspecies of Thamnophis radix.
- Montane Garter Snake, Thamnophis exsul (Rossman, 1969)
- Highland Garter Snake, Thamnophis fulvus (Bocourt, 1893)
- Giant Garter Snake, Thamnophis gigas (Fitch, 1940)
- Godman's Garter Snake, Thamnophis godmani (Günther, 1894)
- Two-striped Garter Snake, Thamnophis hammondii (Kennicott, 1860)
- Checkered Garter Snake, Thamnophis marcianus (Baird & Girard, 1853)
- Blackbelly Garter Snake, Thamnophis melanogaster
- Gray Blackbelly Garter Snake, Thamnophis melanogaster canescens (Smith, 1942)
- Chihuahuan Blackbelly Garter Snake, Thamnophis melanogaster chihuahuanensis (Tanner, 1959)
- Lined Blackbelly Garter Snake, Thamnophis melanogaster linearis (Smith, Nixon & Smith, 1950)
- Mexican Blackbelly Garter Snake, Thamnophis melanogaster melanogaster (Peters, 1864)
- Redstripe Ribbon Snake, Thamnophis proximus rubrilineatus
- Tamaulipan Montane Garter Snake, Thamnophis mendax (Walker, 1955)
- Northwestern Garter Snake, Thamnophis ordinoides (Baird & Girard, 1852)
- Western Ribbon Snake, Thamnophis proximus
- Chiapas Highland Ribbon Snake, Thamnophis proximus alpinus (Rossman, 1963)
- Arid Land Ribbon Snake, Thamnophis proximus diabolicus (Rossman, 1963)
- Gulf Coast Ribbon Snake, Thamnophis proximus orarius (Rossman, 1963)
- Western Ribbon Snake, Thamnophis proximus proximus (Say, 1823)
- Redstripe Ribbon Snake, Thamnophis proximus rubrilineatus (Rossman, 1963)
- Mexican Ribbon Snake, Thamnophis proximus rutiloris (Cope, 1885)
- Plains Garter Snake, Thamnophis radix (Baird & Girard, 1853)
- Rossman's Garter Snake, Thamnophis rossmani (Conant, 2000)
- Narrowhead Garter Snake, Thamnophis rufipunctatus
- Thamnophis rufipunctatus nigronuchalis (Thompson, 1957)
- Thamnophis rufipunctatus unilabialis (Tanner, 1985)
- Thamnophis rufipunctatus rufipunctatus (Cope, 1875)
- Ribbon Snake, Thamnophis sauritus
- Bluestripe Ribbon Snake, Thamnophis sauritus nitae (Rossman, 1963)
- Peninsula Ribbon Snake, Thamnophis sauritus sackenii (Kennicott, 1859)
- Eastern Ribbon Snake, Thamnophis sauritus sauritus (Linnaeus, 1766)
- Northern Ribbon Snake, Thamnophis sauritus septentrionalis (Rossman, 1963)
- Common Garter Snake, Thamnophis sirtalis
- Longtail Alpine Garter Snake, Thamnophis scalaris (Cope, 1861)
- Short-tail Alpine Garter Snake, Thamnophis scaliger (Jan, 1863)
- Common Garter Snake, Thamnophis sirtalis
- Texas Garter Snake, Thamnophis sirtalis annectens (Brown, 1950)
- Texas Garter Snake, Thamnophis sirtalis annectens
- Red-spotted Garter Snake, Thamnophis sirtalis concinnus (Hallowell, 1852)
- New Mexico Garter Snake, Thamnophis sirtalis dorsalis (Baird & Girard, 1853)
- Valley Garter Snake, Thamnophis sirtalis fitchi (Fox, 1951)
- California Red-sided Garter Snake, Thamnophis sirtalis infernalis (Blainville, 1835)
- Thamnophis sirtalis lowei (Tanner, 1988)
- Maritime Garter Snake, Thamnophis sirtalis pallidula (Allen, 1899)
- Red-sided Garter Snake, Thamnophis sirtalis parietalis (Say, 1823)
- Puget Sound Garter Snake, Thamnophis sirtalis pickeringii (Baird & Girard, 1853)
- Bluestripe Garter Snake, Thamnophis sirtalis similis (Rossman, 1965)
- Eastern Garter Snake, Thamnophis sirtalis sirtalis (Linnaeus, 1758)
- Chicago Garter Snake, Thamnophis sirtalis semifasciatus (Cope, 1892)
- San Francisco Garter Snake, Thamnophis sirtalis tetrataenia (Cope, 1875)
- Sumichrast's Garter Snake, Thamnophis sumichrasti (Cope, 1866)
- West Coast Garter Snake, Thamnophis valida
- Mexican Pacific Lowlands Garter Snake, Thamnophis valida celaeno (Cope, 1860)
- Thamnophis valida isabellae (Conant, 1953)
- Thamnophis valida thamnophisoides (Conant, 1961)
- Thamnophis valida valida (Kennicott, 1860)
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