The term "cottonmouth" commonly refers to the Agkistrodon piscivorus, a venomous snake found in the southeastern United States. It is named for its white, cotton-like interior of the mouth, which it displays when threatened. Cottonmouths are semi-aquatic and often inhabit swamps, marshes, and rivers, where they hunt for fish and amphibians. Cottonmouths are typically dark brown or black, with a distinctive triangular head. They can grow up to 4 feet long and are known for their aggressive behavior when cornered. Their venom is potent, but bites are rare, as they usually prefer to escape rather than confront humans.