EVIDENCE OF BLUE COLORATION IN A POPULATION OF PRAIRIE CRAYFISH (PROCAMBARUS GRACILIS (BUNDY, 1876) (DECAPODA, CAMBARIDAE)) IN NORTHEASTERN ILLINOIS, USA

Unique color variations, including the presence of blue coloration, have been documented in individuals of a number of species of crayfish. Color variation in crayfish has largely been attributed to genetic factors, although changes in environmental factors, such as background coloration, water chemistry, light, or diet have also been believed to influence coloration. This study documents the presence of blue coloration in a population of Procambarus gracilis (Bundy, 1876) in northeastern Illinois, U.S.A., and examines possible causes for the blue color in this species. To my knowledge, this is the first documentation of the occurrence of blue coloration in P. gracilis.