Northern Crayfish
Northern crayfish are native Colorado crustaceans.
About This Species
Northern crayfish are primarily nocturnal and less aggressive than other closely related species of crayfish. In its northernmost range the northern crayfish has been known to retreat into deeper waters to avoid freezing, and may get covered in silt while it rests inactive in the depths. The northern crayfish has been known to compete directly with the rusty crayfish (Orconectes rusticus), an invasive species in Colorado.
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Physical Characteristics
The northern crayfish is often confused with the spothanded crayfish (Orconectes punctimanus) and the papershell crayfish (Orconectes immunis). The mature adults can grow up to 125 mm in length. The body is reddish brown or olive brown in color. The claws have yellow bumps on the medial sides, and often display orange or orange-red tips with dark specks. There may also be paired black blotches along the abdomen, especially prominent in the young and individuals that have recently molted.
Range
The northern crayfish has one of the largest native ranges of all North American crayfish. Its Native range includes: Arkansas, Colorado, Illinois, Indiana, Kansas, Kentucky, Maine, Michigan, Minnesota, Missouri, Texas, Utah, Wisconsin, and Wyoming. Its ever-expanding range is most likely due to bait movement.
Habitat
Like O. immunis, the northern crayfish has a broad although somewhat more northerly distribution across North America, from the Atlantic to the Rockies. Whereas the papershell crayfish thrives in muddy and weedy habitats, the northern crayfish generally does best in cooler, rockier environments. The northern crayfish is primarily found in streams, preferring rocky (cobble) substrate with rocky crevices. It prefers fertile, warm, moderately turbid streams with lots of cover such as rocks, logs, and other organic debris. The northern crayfish digs pits in river banks and under rocks, especially when water levels are low. It can tolerate temperatures of 32°F to 89.6°F, but prefers temperatures between 75.2°F and 77°F.
Diet
Adults feed on a variety of live and dead plant and animal material.
Reproduction
Male northern crayfish have been known to construct special tunnels in which mating and brooding of the eggs and young occur. The eggs are laid from mid-March to mid-April, with young emerging from mid-May until the third week in June. Maturity is reached during the second summer of life, with the maximum lifespan of about 3 years.