Plainbelly Water Snake
Nerodia erythrogaster

Statewide, except for isolated portions of the panhandle.  The plainbelly water snakes are our most common water snake, found in or around nearly any permanent water source. These harmless snakes sometimes venture far from water in search of food, which consists primarily of fish and frogs. They can become extremely defensive when disturbed and emit a foul musk or odor to deter predators. They have the ability to flatten their head when first encountered, giving them the appearance of a venomous snake. We have two varieties of plainbelly water snakes in Oklahoma, the blotched water snake, Nerodia erythrogaster transversa (pictured), and the yellowbelly water snake, N. e. flavigaster, found only in the extreme southeast corner of the state.

Many people often confuse these harmless water snakes with the venomous water moccasin. Here are a few identifying characteristics. Water snakes will often swim with most of their body submerged and their head just barely above the surface of the water. They have round pupils, with large conspicuous eyes resting on top of their head. They also tend to be fairly slender built. They also lack the heat-sensitive pits, characteristic of all our venomous snakes. A water moccasin will swim with their entire body above the surface and their head held well above the surface. Their eyes are not as conspicuous and have elliptic pupils (cat eyes), and do not rest on top of the head. Instead, their eyes are almost hidden by a band that is the same color as the eyes. Even a small water moccasin has a very robust build, for better buoyancy in the water.