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.

         

Taxonomic Breakdown

 

Superkingdom              Eukaryota

Kingdom                       Animalia

Subkingdom                 Metazoa

Phylum                          Arthropoda

Subphylum                    Crustacea

Class                                      Malacostraca

Subclass                       Eumalacostraca

Superorder                             Eucarida

Order                                      Decapoda

Suborder                       Astacidea

Superfamily                  Astacoidea

Family                           Astacidae

Genius                          Pacifastacus

Species                        leniusculus

 

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