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
Grass snake Grass snake The grass snake ("Natrix natrix"), sometimes called the ringed snake or water snake, is a Eurasian non-venomous snake. It is often found near water and feeds almost exclusively on amphibians. The barred grass snake, "Natrix helvetica", was split off as a separate species in 2017. The name "natrix" is probably derived from the Latin "nare" or "natare" "to swim"; it means "something grammatically feminine which swims". Many subspecies are recognized, including: "Natrix natrix helvetica" (Lacépède, 1789) was formerly treated as a subspecies, but following genetic analysis it was recognised in August 2017 as a separate species, "Natrix helvetica",