The coldwater crayfish is a medium-small, stout crayfish with a blue-green head and pincers and a dark rust-brown carapace. The abdomen has a pair of conspicuous white lateral spots on the first segment, and a tapering V-shaped dark central stripe. This crayfish is distinguished from other crayfish within its range by the distinctive red and green color and V-shaped central stripe on the abdomen.
Similar species: In 2018, researchers showed that the coldwater crayfish, as originally understood, actually comprised three species:
- the coldwater crayfish, which now is understood to occur only in the Eleven Point River system (formerly, it was understood to be in the Spring River system as well),
- the Eleven Point River crayfish (Faxonius wagneri), a newly described species, which occurs in a 54-mile stretch of the Eleven Point River mainstem (ranging from just southeast of Greer, in Oregon County, Missouri, to just north of Birdell, in Randolph County, Arkansas); and
- the Spring River crayfish (Faxonius roberti), a newly described species, which occurs in the mainstem of the Spring and Strawberry river systems in northern Arkansas (and, apparently historically, from Missouri's portion of the Spring River as well).
Except for the different streams and ranges, genetic differences, and minute details of the reproductive appendages, these all would appear to most people to be coldwater crayfish. The crayfishes, however, apparently do not interbreed.
Adult length: about 1¼ to 2¾ inches.
The coldwater crayfish has a very localized distribution in the Eleven Point River in the Ozark Region in southern Missouri and Arkansas.
Habitat and Conservation
In the Eleven Point River, this is the most abundant crayfish. It occurs over coarse gravel and rock substrate in swift, shallow water. It is often found beneath rocks, in cavities that it excavates in gravel and sand.
This is an aptly named crayfish: the water temperature, as it gushes forth from Mammoth Spring, is 58 F, year-round.
The coldwater crayfish has a limited distribution, and its populations are threatened by the ringed crayfish, which was introduced into the coldwater crayfish's native waters and has proven invasive in those drainages.
Crayfish are generally omnivores, eating a wide variety of plant and animal materials.
State endangered; a Missouri species of conservation concern ranked as critically imperiled. The coldwater crayfish is rare and found only in a small range, so it is vulnerable to extirpation. The Eleven Point River is clear and cold and fed by Greer Spring, one of the largest springs in the Ozarks. It is the most abundant crayfish in the Eleven Point River (downstream of Greer Spring), but it does not live in its tributaries. Populations are threatened by the presence of the ringed crayfish, a species that is invasive in the coldwater crayfish's native range.
The two new species that were split away from the coldwater crayfish in 2018 are also listed as species of conservation concern. (See Description for more about the two new species.) The Eleven Point River crayfish is ranked as as critically imperiled in Missouri, and the Spring River crayfish is ranked as "historic" and endangered in Missouri. At this time, the two new species have not yet been ranked federally.
Mating occurs in the fall, beginning in mid-September and probably extending into November, and females carry eggs between March and May. Some become sexually mature by the end of their first year, but most reach maturity during their second year. The normal life span seems to be about two and a half years.
Crayfish feed many types of wildlife, including many species that humans hunt and fish. Crayfish commonly serve as bait, plus many people eat crayfish, too. Crayfish are fascinating, colorful creatures and are part of our rich natural heritage.
Their opportunistic, omnivorous feeding makes crayfish an important link in the food chain between plants and vertebrates, breaking down plant and other materials that are resistant to decomposition. Crayfish in turn are an important food for many other animals.