Cottonmouth

The cottonmouth, Agkistrodon piscivorus, also called the water moccasin, is a venomous pit viper of the subfamily Crotalinae and one of the world's few semiaquatic vipers, native to the southeastern United States from the Great Dismal Swamp of southeastern Virginia south through the Florida peninsula and west to Arkansas, including coastal barrier islands. Its scientific name combines Greek roots for fish-hook and tooth with Latin for fish-eater; adults typically exceed 80 centimeters, females smaller than males, with a broad head distinct from the neck and variable brown-to-black coloration, often crossbanded, that fades with age, while juveniles show more contrast and yellowish or greenish tail tips. The most aquatic member of its genus, it favors shallow swamps, marshes and slow streams, and when threatened it displays a characteristic defensive gape exposing the white interior of its mouth, the source of its common name.