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Species Description

Piedmont Blue Burrower

Cambarus (Depressicambarus) harti


Classification

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

Description

The Piedmont Blue Burrower is dark blue in color dorsally (on its back) and its abdomen is marked with distinctive tan splotches. The chelae are about 2 times as long as they are broad and are adorned with a row of 5-7 pinkish-cream to white tubercles (small bumps). Its eyes are small and the abdomen is narrower than the cephalothorax (the fused head and thoracic region). The areola is very narrow and has only 1 spot or pit in the narrowest portion. The rostrum lacks spines and tubercles. The carapace length usually measures less than 35 mm (1.4 in) and the total body length is often less than 65 mm (2.6 in).

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus harti 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. The life cycle of this species is presumed to be fairly similar to the generalized crayfish life history described below. Copulation probably 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

Adult Piedmont Blue Burrowers are found in complex burrows in sandy areas near streams or with a high water table (a water level near the surface). The burrows of this species often have 2-4 openings, with at least one chamber that extends below the water table. The openings of the burrow are usually marked with well-developed chimneys (mounds of sand or mud placed around openings above ground). Occasionally it leaves the general safety of its burrow to search for food or a mate at night. Crayfish are generally omnivorous scavengers, feeding upon any food source available within their habitat. Food for this species may include plant material, insects and perhaps other crayfish. 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 this species of crayfish are probably dogs, frogs, turtles and raccoons. Crayfish usually walk slowly using their last 4 walking legs (periopods). When frightened or in danger, however, they quickly escape by "darting" backwards.

Range

The Piedmont Blue Burrower is found in the Piedmont region of the Chattahoochee and Flint River basins in Meriwether County , Georgia . It builds complex burrows in sandy soil in areas near streams or with a high water table.

Conservation Status

This species is listed as Rare in Georgia due to its extremely limited range within the state. Populations appear to be small, but surveys for the Piedmont Blue Burrower can be difficult because they require carefully studying several burrow openings to determine if the crayfish "is home." Recent surveys have found more populations of this crayfish, but its distribution is still limited to one county. Urbanization, habitat destruction and pollution pose possible threats to this species.

Similar Species

The Piedmont Blue Burrower is fairly distinct within its very narrow range. Its combination of blue color, small eyes, narrow areola and complex burrow homes distinguish this crayfish from other species within its range.