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Species Description

Crayfish

Cambarus (Hiaticambarus) coosawattae


Classification

Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Cambaridae

Description

The carapace length of this freshwater crayfish often measures between 19.0 and 35.0 mm (0.75-1.4 inches). The abdomen is narrower and shorter than the carapace. This crayfish is pale olive brown with a narrow band of burgundy along the rear margin of the carapace. The periopods (walking legs on thoracic region) have orange to red margins. The tail has orange to red spines and spots. Rostrum margins are adorned with small spines or tubercles (bumps). The right chela (claw) is about 2 times as long as it is broad and is decorated with tubercles. The areola is 3-4 times as long as it is wide.

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus coosawattae is limited to the form or condition of specimens collected during certain times of the year. First-form (sexually mature) males have been collected during April, June, September and October. Egg-bearing females have been collected during April and June. Copulation usually occurs between autumn and spring. This process involves a sexually mature male crayfish grabbing a female and depositing sperm packages (spermatophores) into the seminal receptacle on the abdomen of a receptive female crayfish. Usually during the spring, females secrete a sticky substance on the underside of their abdomen and pleopods in order to attach their eggs. The eggs and sperm (from the seminal receptacle) are then released upon the sticky surface and fertilization occurs. Females of this species usually carry 20 to more than 100 eggs on the legs and abdomen of larger individuals. A female carrying eggs on her abdomen and legs is said to be "in berry." Embryos develop and hatch on the underside of females in 2-20 weeks, likely depending upon species and temperature. The immature hatchlings molt (shed their exoskeleton to allow growth) and remain attached to their mother. These first-stage immature crayfish look fairly similar to typical crayfish, but have disproportionately large heads and eyes. Another molting takes place in about 1-2 weeks. These second-stage immature crayfish look even more like adult crayfish. Second-stage or third-stage immature crayfish leave their mother's surface and become independent. These young crayfish continue molting and growing and are usually sexually mature by their second or third autumn. Sexually mature males and females are believed to mate between autumn and late spring and many usually die within 3 years of hatching.

Natural History

Adult Cambarus coosawattae crayfish often hide under rocks in riffle areas of streams during the day. From dusk until dawn, or on very cloudy days, crayfish come out of hiding and search for food in streams. Crayfish are usually omnivorous scavengers, feeding upon whatever is available. Crayfish eat aquatic vegetation, small fish, aquatic insects and snails. They use their chelae (claws) on their first 3 legs to grab, crush and tear their food. This food is further cut by a number of specialized mouthparts. The main predators of crayfish are fish, frogs, turtles, wading birds, raccoons, otters and humans. Crayfish usually walk slowly across the bottom of their stream habitat using their last 4 walking legs (periopods). When frightened or in danger, however, they quickly escape by "darting" backwards. Crayfish sometimes have extensive scaring on their chelae or are missing appendages. This occurs while escaping predators or fighting with other crayfish. Male crayfish are particularly aggressive with one another and their claw-to-claw combat can be quite intense.

Range

Cambarus coosawattae has a very limited range. It is only found in moderate to swiftly flowing streams of the Upper Coosawattee River system in Gilmer County, Georgia.

Conservation Status

This crayfish species is listed as Rare and Imperiled within its extremely small range in Georgia. It is threatened by reservoir construction, which has fragmented its range. Like many freshwater crayfish in the Southeast, this species is susceptible to water quality degradation and pollution.

Similar Species

Cambarus longirastris is the most similar crayfish species to Cambarus coosawattae. However, C. coosawattae has tubercles or spines on its rostrum, orange to red markings on its walking legs and is apparently limited to Gilmer County .