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.