Garter snakes can be venomous and poisonous at the same time
Garter snakes of genus Thamnophis range from central Canada to Costa Rica across roughly thirty-seven species and fifty-two subspecies. Early-2000s work showed they make mild neurotoxic venom—and after eating toxic newts they can store tetrodotoxin in the liver, becoming poisonous as well.
Linnaeus described the eastern garter snake in 1758; Fitzinger named Thamnophis in 1843. Lengths span about 46 to 130 centimeters, with keeled scales, round pupils, and usually longitudinal stripes that may flash blue, yellow, or red. They occupy all lower forty-eight U.S. states and Canadian provinces, reaching Guatemala and Costa Rica, and have bred on Newfoundland since at least 2010 after accidental arrival. Habitats stay near water because amphibians bulk large in the diet.
Complex pheromone trails guide mates; some males emit both male and female cues after hibernation to steal heat in mating balls and win more copulations. A clutch may hold fifty-seven young. Disturbed snakes may strike, hide the head, flail the tail, or void a musky cocktail of short-chain acids and amines. Ontario researchers tracking over three thousand Butler's garter snakes for twelve years on 250 hectares near Windsor found stable social groups of three or four, sometimes up to forty-six.
Diet is anything overpowered: worms, frogs, fish, rodents—though redworms are toxic to them. Venom yields only mild human swelling; delivery teeth are rear-fanged and inefficient. Coevolution with toxic newts tunes tetrodotoxin resistance and leaves predators poisonous for weeks afterward. Collection, pollution, bullfrogs, and crayfish pressure some taxa—the San Francisco garter snake has been federally endangered since 1969—yet the genus remains among North America's most often met reptiles.
Source: Garter snake
