| Garter snake | |
|---|---|
| |
| The eastern garter snake (Thamnophis sirtalis sirtalis) | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Colubridae |
| Subfamily: | Natricinae |
| Genus: | Thamnophis Fitzinger, 1843 |
| Species | |
|
35, see text | |
| |
| Thamnophis distribution | |
| Synonyms[1] | |
|
Atomarchus, Chilopoma, Eutaenia, Eutainia, Phamnovis, Prymnomiodon, Stypocemus, Tropidonote, Tropidonotus | |
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.
With about 35 recognized species and subspecies, garter snakes are highly variable in appearance; generally, they have large round eyes with rounded pupils, a slender build, keeled scales (appearing ‘raised’), and a pattern of longitudinal stripes that may or may not include spots (although some have no stripes at all). Certain subspecies have stripes of blue, yellow, or red, mixed with black tops and beige-tan underbelly markings. They also vary significantly in total length, from 18 to 51 in (46 to 130 cm).
With no real consensus on the classification of the species of Thamnophis, disagreements between taxonomists and disputed sources (such as field guides) are common. One area of debate, for example, is whether or not two specific types of snake are separate species, or subspecies of the same. Garter snakes are closely related to the genus Nerodia (water snakes), with some species having been moved back and forth between genera.
Garter snakes have been found to be one of the few species of snakes in the world to be both venomous and poisonous. However both are so medically insignificant that it would be extremely unlikely to harm even a human baby. The poisonous aspect comes from their diet so if they are not eating poisonous frogs they are not in fact poisonous as an individual.