crayfish or crawfish, freshwater crustacean smaller than but structurally very similar to its marine relative the lobster, and found in ponds and streams in most parts of the world except Africa. Crayfish grow some 3 to 4 in. (7.6–10.2 cm) in length and are usually brownish green; some cave-dwelling forms are colorless and eyeless. They are scavengers, feeding on decayed organic matter and also on small fish. The swamp crayfish digs a burrow up to 3 ft (91 cm) deep with a water-filled cavity at the bottom in case of drought. The eggs develop while attached to the swimming legs of the female and look like miniature adults when hatched. Although crayfish are not eaten in most parts of the United States, they are consumed in areas in the Mississippi River basin and are used in the Louisiana area in a thick soup called crayfish bisque. They are agricultural pests in the Mississippi Delta area, where they feed on sprouting wheat and corn. A red-clawed species is considered a delicacy in Europe. Crayfish are classified in the phylum Arthropoda, subphylum Crustacea, order Decapoda.