There are many non-venomous water snakes in Tennessee that can be identified by their slender body shape, flattened or slender head, non-distinct neck and round eye pupils. There is one venomous water snake, known as the western cottonmouth, found west of the Tennessee River.
Cottonmouths are also called water moccasins. They can be identified by their heavy body shape, thick and blocky head, narrow neck and vertical eye pupils. Adult cottonmouths are 30 to 42 inches long. They are found near water, where they eat fish and amphibians. Cottonmouths have a dull appearance, making them seem almost black. Their venom is hemotoxic, meaning it destroys red blood cells and disturbs blood clotting. Death from cottonmouth bites are rare.