These snakes are one of several water snakes that live in Illinois, but it is one of the most common, according to the Illinois Department of Natural Resources. A similar species, the midland water snake, is actually a subspecies of the northern water snake. The two species interbreed, creating snakes that show traits of both species.
Cottonmouths hunt prey in water or on land. They eat fish, small mammals, birds, amphibians and reptiles — including other snakes and even smaller water moccasins, according to the University of Michigan’s Animal Diversity Web (ADW). Cottonmouths kill with a single, venomous bite, then wrap around their prey until it stops moving before swallowing their food whole.
Cottonmouths rarely bite humans unless they are picked up or stepped on. They may stand their ground against potential predators, including humans, by using defensive behaviors.
Updated on Live Science Aug. 16, 2023.
The northern water snake is a medium-sized snake, generally between 2 feet and 4 feet long, and females are usually larger than males. These snakes are dark-colored, ranging from brown to reddish-brown to gray, and their bellies are cream-colored or yellow, the Missouri Department of Conservation reports. They have distinct bands, or stripes on their backs, that can be black, gray, dark brown or reddish-brown in color. These bands taper into blotches further away from their heads.
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Cottonmouths (Agkistrodon piscivorus), also called water moccasins, are venomous snakes found in the southeastern United States. They’re called cottonmouths because of the white coloration on the inside of their mouths, which they display when threatened.
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These water snakes are not constrictors, like boas and pythons. Instead, they swallow their prey while it is alive. Northern water snakes have been known to herd fish and tadpoles to the edges of the water, where they can easily eat them one at a time.
A western cottonmouth snake coiled up and displaying its white mouth. (Image credit: Rex Lisman via Getty Images)
Cottonmouth snakes: Facts about water moccasins
These snakes do not stay in water exclusively, although they are never too far from an aquatic environment. They often bask in the sun on rocks and branches near water or over water.
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Where they live
Cottonmouths range from southeastern Virginia to Florida, west to central Texas and north to southern Illinois and Indiana, according to the International Union for Conservation of Nature. They primarily live in aquatic and wetland habitats, including swamps, marshes, drainage ditches, ponds, lakes and streams.
“When a cottonmouth feels threatened, it will coil its body and open its mouth wide to expose the white coloration of the inside of its mouth,” Viernum said. The flash of white contrasts with the snake’s dark body colors to create a startling display. “Exposing the white of the mouth serves as a warning signal to potential predators.”