Crayfish

Crayfish

Classification

Crayfish, also called crawfish or crawdads, are freshwater crustaceans found on all of the warm continents. They are closely related to American lobsters. Crayfish are generally only a few inches long, but Astacopsis gouldi, crayfish native to Tasmania, grow as large as average-size lobsters.

Crayfish makeup the families Astacidae, Parastacidae, and Austroastracidae. They range in length from 2 to 40 cm (0.8 to 16 in). Their thin, hard exoskeleton is usually brownish green, but may also be white, pink, red or blue.

Range

Crayfish live in streams and ponds throughout the world, hiding under stones during the day and feeding at night.

Habitat

Crayfish live in ponds, lakes, and streams where they eat small animals and dead or decaying materials. Some live partly on land and dig burrows in soft areas of mud or clay. Mounds of dirt piled about crayfish burrows are a common sight in many parts of the southern United States.

Diet

Crayfish eat decaying plant and animal matter in addition to small fish, snails, insect larvae, and worms.

Gestation

Crayfish mate in the fall, others mate in the spring. Males and females can be differentiated by the first pair of swimmerets under their abdomens. The first pair of swimmerets in a male are specialized copulatory organs. In both groups, sperm from the male are deposited and stored in the semnial receptacle of the female. Hundreds of tiny eggs which are first fertilized by the sperm from the seminal receptacle arre expelled from the oviducts. The eggs are attached to the pleopods by means of a secretion that hardens to a cement. Then the female takes refuge in her nest to protect her developing eggs. One month later the eggs hatch.

Longevity

Crayfish can live up to three years or longer.

Conservation

In many parts of the world crayfish are eaten as food and used as live fish-bait. In the United States their use as food is limited chiefly to areas around the Mississippi River basin. A thick soup, crayfish bisque, is a popular Louisiana dish.

Bibliography

Compton's New Media, Inc., 1993