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Species Description

Crayfish

Cambarus (Jugicambarus) asperimanus


Classification

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

Description

The carapace of Cambarus asperimanus is olive to orange-brown in color, with creamy blotches. The 1 st abdominal segment is mostly brown. The other abdominal segments are light olive and decorated with pairs of dark brown splotches. This crayfish has small eyes and a very short rostrum that lacks both spines and tubercles. The chelae (claws) are quite hairy and adorned with a single row of 5-6 tubercles (small bumps). The areola is of medium width, with 2-4 spots in the narrowest portion. The carapace length is usually less than 31 mm (1.2 in). The total body length often measures less than 57 mm (2.2 in).

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus asperimanus is limited to the form or condition of specimens collected during certain times of the year. First-form (sexually mature) males have been collected from May to October. Egg-bearing females have been collected during April, June and December. The life cycle of this species is presumed to be fairly similar to the generalized crayfish life history described below. The mating season for this species is unknown. 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. During the appropriate time(s) of year, 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. Many adult crayfish die within 3 years of hatching.

Natural History

Adult Cambarus asperimanus crayfish often hide between rocks and amongst leaf litter in cascading stream areas. This species prefers quick-flowing, clean mountain streams at altitudes between 700 and 1300 m (2297-4265 ft). 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, detritus, 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 especially aggressive with one another and their claw-to-claw combat can be quite intense.

Range

This species is found in the Watuga Basin of Tennessee and in mountain streams in North Carolina , South Carolina and Georgia . It frequents streams within the French Broad , Catawba, Little Tennessee, Broad, Saludia and Savannah River basins . Within Georgia , it is found in mountain streams within the Savannah River basin near the Georgia/South Carolina and Georgia/North Carolina borders in Rabun and Stephens counties.

Conservation Status

Although it is widespread in several rivers throughout its range, this species is listed as Rare in Georgia . It has a limited range in Georgia and is threatened by habitat destruction, pollution and other forms of water quality degradation.

Similar Species

Within its limited mountain stream range in Georgia , this species is usually fairly distinct. The dark brown splotches on its abdomen and creamy blotches on its carapace should distinguish this species from others in Rabun and Stephens counties.