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
Sinonatrix percarinata Sinonatrix percarinata Sinonatrix percarinata, commonly known as the Eastern water snake, olive keelback, or Chinese keelback water snake, is a species of snake in the subfamily Natricinae. The type locality for "S. percarinata" is Guadun (formerly spelled as Kuatun), Wuyishan City (former Chongan County) in NW Fujian, China. The subspecies "Sinonatrix percarinata suriki" is endemic to Taiwan where it occurs in the whole country. "S. percarinata" is an aggressive snake that bites readily when caught, but it is not venomous. It is a medium-sized snake, typically attaining a total length (including tail) of , but may grow up to .