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The crayfish are any of several lobsterlike crustaceans that inhabit fresh water in most parts of the world. Crayfish range in length from 1 to 18 inches. Most of them are dark brown-green, but some are white or pale pink, and a few species are bright blue.
Like its close relative the lobster, the crayfish has a body consisting of an abdomen and a combined head and thorax, called a cephalothorax. Its entire body is divided into segments, but only the segments in the abdomen can be moved. Covering the body is a hard horny structure, called the exoskeleton. In order to grow, the crayfish sheds its entire exoskeleton from time to time, swallows water to swell up its soft body, and then hardens a new outer covering.
The crayfish has a pair of short double-branched feelers, called antennules; a pair of long slender an#tennae; and a pair of large bulging eyes borne on short movable stalks. It uses a pair of large pincerlike claws to capture and hold its prey. Along the sides of its body behind the claws are four pairs of walking legs. Along the underside of the abdomen are five parrs of small thin appendages, called swimmerets, used for creating a forward current of water under the body. The female uses her swimmerets to carry her 200 to 300 eggs until they hatch. The end of the tail, together with a pair of flat, fan-shaped appendages, forms a tail fin used for swimming backward.
Most crayfish live in streams and ponds, hiding under flat stones with only their antennae and claws exposed to snatch at small fish and other animals. Crayfish also feed on dead plants and animals.
Crayfish are a popular food in Europe, but they are less often eaten in the United States except in Louisiana. In New Orleans, La., they are frequently made into a thick soup, called crayfish bisque. Crayfish are also used as fish bait during the periods when they are soft-bodied, having just shed their exoskeletons.