All but seven of Oklahoma's 46 species of native snakes lack venom. The state's venomous snakes belong to the pit-viper subfamily, distinguished by the presence of facial grooves with heat sensors between the snake's eye and nostril. All snakes, venomous or not, rarely tangle with people unless provoked, but for safety's sake – and a greater appreciation of local ecology – it's a good idea to familiarize yourself with Oklahoma's common serpents if you live or recreate here.
Rattlesnakes – members of the Crotalus family – account for the majority of venomous snakes in Oklahoma. Oklahoma's rattlesnakes include the western pygmy, western massasauga, timber, prairie and western diamondback varieties. When alarmed or threatened, rattlesnakes shake the namesake rattles at the ends of their tails as a warning. The largest rattler in Oklahoma, the western diamondback, may grow to more than 7-1/2 feet long.
Other Venomous Snakes
Copperheads and cottonmouths are the two other venomous snakes in Oklahoma. As their name suggests, copperheads have light brown or copper scales with reddish splotches all over their bodies. Cottonmouths get their name from the white-colored flesh inside their mouths; when irritated, the cottonmouth will open its mouth, revealing that characteristic white. Copperheads don't have rattles, but they will still shake their tails if they are about to strike.
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While some venomous snakes – the cottonmouth, or "water moccasin," for instance – spend time in aquatic habitats, Oklahoma's true water snakes are nonvenomous. Nonvenomous water snakes belong to the Nerodia genus. Diamondback, broad-banded, northern and plain-bellied water snakes all call Oklahoma home. Some Nerodia snakes bear a striking resemblance to venomous snakes: Diamondback water snakes, for example, look like diamondback rattlesnakes and northern water snakes have a similar appearance as cottonmouths. However, Nerodia water snakes swim entirely underwater, while venomous snakes swim near the surface.
Garter snakes in the family Thamnophis rank among the most common snakes in Oklahoma. The common garter, a native Oklahoman, is actually the most widely distributed snake in the United States. Humans frequently see garter snakes, since they are not afraid to approach urban gardens and backyards. Oklahoma's other Thamnophis snakes include the Marcy's checkered garter snake, orange-striped ribbon snake, western black-neck garter snake and plain garter snake. Identify garter snakes by the solid stripes on their bodies.
Three kingsnake species are native to Oklahoma: the milksnake, prairie kingsnake and speckled kingsnake. All three kingsnakes live throughout the state. People often mistake the milksnake for the coral snake, a venomous snake not native to Oklahoma. Speckled kingsnakes have black skin with yellow dots all over the body. Kingsnakes often prey on other snakes, including venomous species and fellow kingsnakes.