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Species Description

Little Tennessee Crayfish

Cambarus (Puncticambarus) georgiae


Classification

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

Description

The carapace of the Little Tennessee Crayfish is greenish, bluish gray or orange-red and is marked with distinctive dark, saddle-like markings. Its abdomen is longer and narrower than its carapace. The chelae (claws) are about twice as long as they are wide and are adorned with a row of 8-20 tubercles (small bumps). The carapace usually measures less than 30 mm (1.2 in) and the total body length is often less than 65 mm (2.6 in). The rostrum has a long, narrow acumen (the tip of the rostrum near the antennae) and is adorned with spines or tubercles at the margins. The areola is broad and has 8-10 small spots or pits in the narrowest portion.

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus georgiae is limited to the form or condition of specimens collected during certain times of the year. First-form (sexually mature) males have been collected in April and May. An egg-bearing female was collected in April. The ovigerous (egg-bearing) female was carrying 73 eggs. The life cycle of this species is presumed to be fairly similar to the generalized crayfish life history described below. Copulation usually occurs during autumn and spring. Copulation 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. 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 during autumn and spring. Many adult crayfish die within 3 years of hatching.

Natural History

unable to compete with C. bartonii in the riffle areas of streams in its range and is most often found in slower portions of streams that are free of C. bartonii.

Range

This species is limited to a 50 mile stretch of the Upper Little Tennessee River in Rabun County , Georgia and Macon County , North Carolina . This species prefers the slower parts of moderately flowing streams with sandy-clay substrates. It is usually found hidden beneath leaf litter and appears to be unable to compete with C. bartonii in riffle portions of streams in its limited range.

Conservation Status

The Little Tennessee Crayfish is listed as Rare in Georgia due to its extremely limited range. It does not appear that there are any immediate threats to this rare crayfish in Georgia , but like many crayfish it is susceptible to future water quality degradation, pollution and habitat degradation.

Similar Species

This species can be difficult to distinguish from several other species of Cambarus (Puncticambarus). Accurate identification relies upon subtle anatomical features and differences that are usually best distinguished by trained individuals.