Diamondback Water Snake
Nerodia rhombifer

Central part of the state.  The diamondback water snake is the largest and most aggressive water snake in Oklahoma. Easily distinguished from the other species of water snakes, the diamondback has typically a dark green to brown body ground color with a black net-like pattern, forming a rhomboid pattern, giving this species its name. Like all water snakes, they are found near water, but may wander far from water in search of food, which includes fish, frogs, salamanders, and crustaceans.

*Water snakes are easily distinguished from the venomous cottonmouth in that they have round pupils, with eyes set higher on top of the head, typically a very yellow lower jaw and throat, and each labial scale has a very noticeable black edge.