Crayfish are characterized by a joined head and thorax, or midsection, and a segmented body, which is sandy yellow, green, red, or dark brown in colour. The head has a sharp snout, and the compound eyes are on movable stalks. The exoskeleton, or body covering, is thin but tough. The front pair of the five pairs of legs have large, powerful pincers (chelae). There are five pairs of smaller appendages on the abdomen, used mostly for swimming and circulating water for respiration.