Pacifastacus leniusculus (Dana, 1852)
Signal Crayfish
Size: Up to 15 cm in
length, from tip of rostrum to end of telson.
Identification: Bluish/brown to reddish/brown in color. Muscular,
large smooth claws. White patch near claw hinge.
Food: P. leniusculus is an opportunistic generalist feeding polytrophically on aquatic
plants, terrestrial plants, algae, carrion, insects, fish eggs, live fish and
snails.
Range: British Columbia,
California, Idaho, Nevada, Oregon, Utah, and Washington. Introduced into
Sweden, Finland, Great Britain and Japan.
Habitat: Rivers, streams and lakes.
Misidentification: Red
Swamp Crayfish (Procambarus clarkii) the carapace is dark red
bordering on black, and there is with a wedge-shaped stripe on the abdomen.
Introduced populations of red swamp crayfish have been found
in the King County area.
Life History: Mating occurs in the fall and females carry the fertilized eggs on
the underside of the abdomen for 7 to 8 months. In the spring when the eggs
hatch the babies (identical to the adult form only smaller) stay with the
mother until their second molt. After the second molt they leave the mother and
start to feed on the same foods as the mother. During the first year an
individual may triple in size. At age three or four they become sexually
mature. Some individuals can live up to ten years.
Predators: Raccoons, Fish, Birds, Rats, Otters, etc.
Superkingdom Eukaryota
Kingdom Animalia
Subkingdom Metazoa
Phylum Arthropoda
Class Malacostraca
Superorder Eucarida
Order Decapoda
Suborder Astacidea
Family Astacidae
Links: Key To The Astacidea <http://crayfish.byu.edu/Keys/index.htm>.
Aguatic Nuisance
Species. Washington State Department of
Fish and Wildlife <http://wdfw.wa.gov/fish/ans/wa_speciesofconcern.htm>.
Suggested Reading: Covich, Alan P. , and James H.
Thorp, ed. Ecology and Classification of North American Freshwater
Invertebrates. San Diego: Academic Press, 1991.
Prepared by Todd Klosterman Spring, 2004