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rusty crayfish
rusty crayfish (Faxonius rusticus) [nonnative]
Photo © Chris Taylor, Illinois Natural History Survey
Features and Behaviors
FEATURES
The rusty crayfish is green-brown to brown-red on the upper side of the body. Single, brown spots are located on each side near the middle of the animal. The claws are fairly smooth and gray-green to red-brown in color.
BEHAVIORS
The rusty crayfish lives in creeks, rivers and lakes with rock or gravel bottoms. This crayfish reaches maturity at about 15 months of age. Mating occurs in the fall with egg-laying in late spring. The number of eggs produced is dependent on the body size of the female, ranging from about 50 to 350. Eggs hatch in May after being carried under the female's tail for about four to six weeks. It overwinters in burrows it constructs in streambanks or in other places in the ground. The rusty crayfish hunts aggressively for food, feeding mainly on plants and dead organisms. The rusty crayfish is native to the southern United States. This species was first collected from Illinois in 1973. It is believed to have been introduced into Illinois by fishermen who used it as fishing bait, releasing the remaining crayfish when they were done fishing. Current laws ban the sale and possession of this species in Illinois. Strictly enforcing these laws is the only way to stop its spread. The rusty crayfish is an aggressive, large species that takes over prime habitat from native crayfishes, forcing them into areas where they are preyed upon more easily. In other places it has caused the elimination of many native crayfish species from their original habitat.
Illinois Range
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Family: Cambaridae
Illinois Status: common, nonnative
