Oklahoma is home to 44 native snake species, all but seven of them nonvenomous. All of Oklahoma's venomous snakes are pit vipers, meaning they have facial grooves with heat sensors. Since pit vipers are nocturnal, the sensors allows these snakes to detect warm-blooded prey. Nonvenomous snakes will bite humans if provoked.
The majority of venomous snakes in Oklahoma are rattlesnakes belonging to the Crotalus family. Oklahoma's rattlesnakes are the western pygmy, western massasauga, timber, prairie and western diamond-backed varieties. These snakes have rattlers attached to the end of the tail. When alarmed or threatened, rattlesnakes shake their rattle as a warning. The largest rattlesnake in Oklahoma, the western diamondback, grows to over 7.5 feet long.
Copperheads and cottonmouths are the two remaining venomous snakes in Oklahoma. As their name suggests, copperheads have light brown or copper scales with reddish splotches all over their bodies. Cottonmouths receive their name from the white-colored flesh inside their mouths; when irritated, the cottonmouth will open its mouth, revealing its white flesh. Copperheads do not have rattlers, but they will still shake their tails if they are about to strike.
While some venomous snakes – cottonmouths and copperheads – spend time in aquatic habitats, many of Oklahoma's water snakes are nonvenomous. Nonvenomous water snakes belong in the Nerodia genus. Diamond-backed, broad-banded, northern and plain-bellied water snakes are all native to Oklahoma. Some Nerodia snakes bear a striking resemblance to venomous snakes; diamond-backed snakes look like diamond-backed rattlesnakes and northern water snakes have the same appearance as cottonmouths. However, Nerodia water snakes swim entirely underwater, while venomous snakes swim near the surface.
Garter snakes in the reptile family, Thamnophis, are among the most common snakes in Oklahoma. One native Oklahoman snake, the common garter, is 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 are the Marcy's checkered garter snake, orange-striped ribbon snake, western black-neck garter snake and plain garter snake. All garter snakes may be identified 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. The milksnake is often mistaken for the coral snake, a venomous snake not native to Oklahoma. Speckled kingsnakes have black skin with yellow dots all over the body. Kingsnakes are known for eating snakes, including venomous species and other kingsnakes. These snakes determine what type of snakes they are about to eat by touching them with the tip of their tongue.