OBJECT OF THE MONTH - August, 2007

Crayfish in Colorado

Specimens of Orconectes nais, dorsal view (UCM #1581: Nebraska, Lincoln County, Medicine Creek) and lateral view (UCM#2515: Colorado, Prowers County, Clay Creek). The top specimen measures about 3 inches (7.62 cm) in length.

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.

Our recent surveys of crayfish in Colorado also have O. nais showing up at lower elevations in western Colorado. Crayfish are an important bait food and spread of certain species is probably tied to human use of the animals. The University of Colorado Museum of Natural History has an excellent collection of crayfish and we can use the distribution information to track the spread (or range contractions) of native and invasive species.
Further reading:
Unger, P. A. 1978. The crayfishes (Crustacea: Cambaridae) of Colorado. Natural History Inventory of Colorado, No. 3. University of Colorado Museum, Boulder, Colorado 80309.