Northern water snake The belly also varies in color. It can be white, yellow, or gray. Usually it also has reddish or black crescents. The northern water snake is nonvenomous and harmless to humans, but superficially resembles the venomous cottonmouth and is often killed unnecessarily as a result of this mistaken identity. The two can be easily distinguished by morphological traits: the water snake has a longer, more slender body and a flattened head the same width as the neck, round pupils, and no heat-sensing pits. The cottonmouth has a fatter body, a wedge-shaped head with prominent venom glands that are wider than
Brown water snake (150 m) elevation. The brown water snake is very heavy-bodied, and its neck is distinctly narrower than its head. Dorsally it is brown or rusty brown with a row of about 25 black or dark brown square blotches down its back. Smaller similar blotches alternate on the sides. Ventrally it is yellow heavily marked with black or dark brown. Dorsal scales are in 27-33 rows (more than any other North American water snake), and it has 2-4 anterior temporals (usually 1 in others). Adults measure 30-60 in. (76–152 cm) in total length; record 69 in. (175 cm). "Nerodia taxispilota" is