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Species Description

Hiwassee Crayfish

Cambarus (Puncticambarus) hiwasseensis


Classification

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

Description

The Hiwassee Crayfish is tan to greenish tan and decorated with brown and grayish-brown splotches. The greenish brown chelae (claws) are long and narrow and adorned with 2 rows of tubercles (small bumps). The eyes of this crayfish are moderately large. The rostrum is fairly long and lacks both marginal spines and tubercles. The carapace usually measures between 24 and 42 mm (0.95-1.7 in) in length.

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus hiwasseensis 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 March through June and during October and November. Egg-bearing females have been collected during June. The life cycle of this species is presumed to be fairly similar to the generalized crayfish life history described below. Based upon the condition of specimens collected during different times of the year, the breeding season of this species is believed to be from October through June. 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." Each female usually carries between 94 and 182 eggs while "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 Hiwassee Crayfish often hide under rocks and leaf debris in swift, clear streams. 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 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 are sometimes found with extensive scaring on their chelae or 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 crayfish is found within streams of the Upper Hiwassee River Basin in northeastern Georgia and southwestern North Carolina . In Georgia , it is found within clear, swift streams in Towns and Union counties.

Conservation Status

The Hiwassee Crayfish is listed as Uncommon and Vulnerable in Georgia . It has a limited range within the state that has been fragmented by the construction of impoundments and reservoirs. Pollution and habitat destruction also threaten this species within Georgia .

Similar Species

The most similar species to the Hiwassee Crayfish is Cambarus parrishi. However, C. parrishi has marginal spines or tubercles on its rostrum and the Hiwassee Crayfish lacks these rostrum adornments.