Crayfish: you might remember them from your high school or college dissections, or from that delicious crayfish étouffée you had last night. These beasties are relatively common in Colorado waters although not nearly as diverse here as in the eastern United States. About half of the diversity of crayfish worldwide is here in North America. This particular species is called Orconectes nais, and is likely an invasive crayfish into Colorado waters. The main part of its range is just to our Southeast in Arkansas, Kansas, and Texas.