The striped crayfish snake (Liodytes alleni) is a species of semiaquatic North American snake in the family Colubridae. The species derives its common name from its principal prey, crayfish. This snake is also called Allen's snake, the striped swamp snake, the striped swampsnake, or simply the swamp snake. It is endemic to peninsular Florida. Although rarely seen due to its secretive behavior, it can be found in large numbers in wet areas, with densities approaching 1,300 snakes per hectare (525 snakes per acre).