Big Creek Crayfish

Media
Photo of a Big Creek crayfish.
Status
Name
Species of Conservation Concern
Scientific Name
Faxonius peruncus (formerly Orconectes peruncus)
Family
Cambaridae (freshwater crayfish), in the order Decapoda (shrimp, crabs and lobsters)
Description

The Big Creek crayfish is a moderately small, brown crayfish without bright colors. Blackish specks and blotches occur over the dorsal surface of the body and pincers (specks are most numerous on the abdomen). The pincers are moderately broad and heavy.

Size

Adult length: about 1 to 2¼ inches.

Where To Find
image of Big Creek Crayfish Distribution Map

The Big Creek crayfish has a very localized distribution that is centered in Big Creek and its tributaries primarily on the west side of the St. Francis River basin. Other populations occur in Clark Creek and Twelve Mile Creek, direct tributaries of the St. Francis River.

A headwater species, the Big Creek crayfish occurs exclusively in small, high-gradient rocky creeks. It lives in cavities that it excavates beneath rocks, on riffles, or in shallow, silt-free ponds. Its distribution largely complements that of the St. Francis River crayfish; the two species might compete because of similarities in habits and habitat. In a only a few locations it has been collected in the same stream as the St. Francis River crayfish.

Crayfish are generally omnivores, eating a wide variety of plant and animal materials.

Imperiled; a species of conservation of concern. The Big Creek crayfish occurs only in Missouri (it is endemic to our state), and it has a very localized distribution in the St. Francis river basin of Iron, Madison, and Wayne Counties. It is most abundant in Big Creek and its tributaries on the west side of the basin. Its distribution is threatened by the woodland crayfish, which is invasive in the Big Creek crayfish's range.

Life Cycle

Like other Ozark stream crayfish, this species has both a fall and a spring reproductive season. Only a few live to be 3 years old. Like insects, crayfish must periodically molt their rigid, shell-like exoskeletons in order to grow. The new shell develops beneath the old one over a period of weeks. Then, the old shell splits on the back, between the carapace and abdomen, and the entire body is withdrawn through this opening. It takes about a week afterward for the new shell to harden.

In addition to feeding many types of wildlife, crayfish provide food for many species that humans hunt and fish. Crayfish commonly serve as fish bait, and many people eat crayfish, too. Crayfish are fascinating, colorful creatures in their own right, and part of our rich native 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.

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About Aquatic Invertebrates in Missouri
Missouri's streams, lakes, and other aquatic habitats hold thousands of kinds of invertebrates — worms, freshwater mussels, snails, crayfish, insects, and other animals without backbones. These creatures are vital links in the aquatic food chain, and their presence and numbers tell us a lot about water quality.