Cottonmouths (Agkistrodon piscivorus), or water moccasins, are venomous snakes found in the southeastern United States. They're called cottonmouths because the insides of their mouths, which they display when threatened, are white.
Cottonmouths are semiaquatic, so they're comfortable both swimming in water and basking on land. They are the only venomous snake in the U.S. that spends a lot of time in the water, Live Science previously reported. Other local names for cottonmouths include black moccasins, gapers, mangrove rattlers, snap jaws, stub-tail snakes, swamp lions, trap jaws, water mambas and water pilots.
