crayfish(redirected from crawdad)
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, primarily aquatic arthropod of the subphylum Crustacea. Most of the 44,000 crustacean species are marine, but there are many freshwater forms. The few groups that inhabit terrestrial areas have not been particularly successful in an evolutionary sense; most require
..... Click the link for more information. smaller than but structurally very similar to its marine relative the lobsterlobster,
marine crustacean with five pairs of jointed legs, the first bearing large pincerlike claws of unequal size adapted to crushing the shells of its prey. The segmented body of the lobster consists of a large cephalothorax (made up of 14 segments) and a moveable, muscular
..... Click the link for more information. , 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 ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
..... Click the link for more information. , subphylum Crustacea, order Decapoda.
an invertebrate of the order Decapoda. The body length is usually 6–30 cm, but some species, such as the Madagascar crayfish, reach a length of 80 cm. Most crayfishes inhabit freshwaters. They are nocturnal animals and hide in their burrows during the day. Crayfishes feed primarily on aquatic vegetation growing near the shore, but occasionally they feed on animal substances. The males are longer than the females and have more powerful claws. Crayfishes reproduce in the fall, after the females molt. The females carry from 50 to 100 eggs on their abdomen.
There are three families of crayfishes, distributed in temperate zones throughout the world, excluding Africa. Eight species of the family Astacidae are found in the USSR, with Astacus leptodactylus and A. astacus having the greatest commercial value. Approximately 90 percent of the entire catch of crayfishes in the USSR is from the basin of the Sea of Azov and the Baltic Sea.
REFERENCESBudnikov, K. N., and F. F. Tret’iakov. Rechnye raki i ikh promysel. Moscow, 1952.
Ivanov, A. V. Promyslovye vodnye bezpovonochnye. Moscow, 1955.