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Species Description

Oconee Burrowing Crayfish

Cambarus (Depressicambarus) truncatus


Classification

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

Description

The Oconee Burrowing Crayfish has a pinkish orange body that is decorated with darker tan-colored markings. The chelae (claws) are mostly orange and have at least 2 rows of tubercles (small bumps). The distinctive areola is linear or nonexistent and lacks both spots and pits. The eyes are small and the broad rostrum lacks spines and tubercles. The carapace length is often less than 37 mm (1.5 in) and the entire body usually measures less than 67 mm (2.6 in).

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Cambarus strigosus 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. Very little information is known about the life history of this species, but the life cycle is expected to be fairly similar to the generalized crayfish life history described below. Copulation has not been observed, but probably occurs from autumn to 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 between autumn and spring. Many adult crayfish die within 3 years of hatching.

Natural History

Adult Oconee Burrowing Crayfish are found in complex burrows in sandy-clay soils in areas with a high water table (a water level near the surface). The constructed burrows often have multiple branches and passageways. At least one chamber extends below the water table. The openings of the burrow are usually marked with 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. Crayfish usually walk slowly using their last 4 walking legs (periopods). When frightened or in danger, however, they quickly escape by "darting" backwards into their burrows.

Range

This species has a very limited range within the Oconee River basin of Laurens and Wilkinson counties in Georgia . This species constructs complex burrows in sandy-clay soil areas with a high water table.

Conservation Status

The Oconee Burrowing Crayfish is listed as Rare in Georgia . It has a limited range and apparently a very small population size. More surveys and studies should be conducted on this species to learn more about its general biology and life history. This species is most likely threatened by habitat destruction.

Similar Species

Within its very limited range, the Oconee Burrowing Crayfish is usually fairly distinct. It is found in complex burrows and its combination of pinkish-orange color and nonexistent areola should distinguish this rare species from other burrowing crayfish in Laurens and Wilkinson counties. Identification should usually be verified by a trained individual.