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
Northern water snake night. It is most often seen basking on rocks, stumps, or brush. During the day, it hunts among plants at the water's edge, looking for small fish, frogs, worms, leeches, crayfish, salamanders, small birds and mammals . At night, it concentrates on minnows and other small fish sleeping in shallow water. It hunts using smell, and sight. The Lake Erie water snake subspecies, "Nerodia sipedon insularum", was once endangered, but now benefits from the introduction of the round goby, an invasive species, which now comprises up to 90% of its diet. The northern water snake is extremely common over most