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
Green water snake Green water snake The green water snake ("Nerodia cyclopion") is a common species of nonvenomous natricine snake endemic to the southeastern United States. "N. cyclopion" is distributed from the Florida panhandle westward to Louisiana, and northward through the Mississippi Valley into southern Illinois. More precisely, it is found in southwestern Alabama, southeastern Arkansas, northwestern Florida, southern Illinois, southwestern Indiana, western Kentucky, Louisiana, southern Mississippi, southeastern Missouri, western Tennessee, and southeastern Texas. The type locality is New Orleans, Louisiana. "N. cyclopion" differs from most other species of North American water snakes by having one or more small scales under the eye,