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Crayfish

Breeding Habits

Crayfish usually mate in the fall. Females excrete pheromones which are detected by the antennules of males. The openings of the sex organs are located on the front end of the abdomen just below the thorax. In the male, the first two pairs of abdominal pleopods are used as organs of sperm transfer. Using his first set of pleopods, the male deposits sperm into a sac on the female's abdomen. The female stays well hidden as ovulation draws near, lavishly grooming her abdominal pleopods which will eventually secure her eggs and hatchlings to her abdomen. Strenuous abdominal contractions signal the onset of egg extrusion. Cupping her abdomen, the female crayfish collects her eggs as they are laid (they can number 400 or more), securing them with her pleopods, fastidiously cleaning them with thoracic appendages, and discarding any diseased eggs.

Young crayfish hatchlings emerge from the eggs in the spring, and closely resemble adult crayfish in form (although much smaller). The hatchlings cling tightly to their mother's pleopods, eventually taking short foraging forays and scurrying back for protection at the slightest disturbance. During this time, the mother remains relatively inactive and is extremely aggressive in protecting her young from other, non-maternal crayfish, which would cannibalize the young. The mother and young communicate chemically via pheromones; however, the young cannot differentiate between their own mother and another maternal female.

See also Crustacea; Shrimp.


Resources

Books

Felgenhauer, Bruce E., Les Watling, and Anne B. Thistle. Functional Morphology of Feeding and Grooming in Crustacea. Rotterdam/Brookfield: A.A. Balkema, 1989.

Hobbs, Horton H., Jr. The Crayfishes of Georgia. Washington: Smithsonian Institution Press, 1981.


Marie L. Thompson

KEY TERMS

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Antennule

—Small antenna on the front section of the head.

Carapace

—Shell covering the cephalothorax.

Cephalothorax

—The head and thorax (upper part of the body) combined.

Chela

—Pinchers on first pair of legs used for defense and food gathering.

Chelipeds

—First pair of pereiopods ending with large pinchers.

Mandibles

—Jaws.

Maxillipeds

—Small leg-like appendages beneath the cephalothorax which aid in feeding.

Pereiopods

—Ten jointed, armor-plated legs attached to the cephalothorax.

Pleopods

—Small, specialized appendages below the abdomen which aid in swimming.

Rostrum

—Beak-like projection at the front of the head.

Telson

—Fan-shaped tail composed of five segments.

Additional topics

Science EncyclopediaScience & Philosophy: Cosine to Cyano groupCrayfish - History And Habitat, Appearance, Breeding Habits