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Species Description

Crayfish

Procambarus (Ortmannicus) acutissimus


Classification

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

Description

This species is highly variable in appearance, making identification difficult. The carapace is brown with scattered dark tan spots and pinkish gray to cream spots. The tail is olive tan in color with brown blotches. The tan chelipeds (large claws) are long and narrow with yellowish-colored tips. The rostrum may or may not have spines or tubercles (small bumps) along the edges. The carapace usually measures less than 36 mm (1.4 in) in length.

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Procambarus acutissimus 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 most months of the year and it is likely that at least some first-form males can be found throughout the year. Females carrying eggs have not been collected and it has been suggested that females remain in their burrows while carrying eggs or young. The life cycle of this species is presumed to be fairly similar to the generalized crayfish life history described below. The exact breeding season of this species is currently 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 P. acutissimus crayfish have been found in a wide variety of habitats, including temporary ponds, roadside ditches and occasionally in constructed burrows. From dusk until dawn, or on very cloudy days, crayfish often 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 species is found from the Tombigee River Basin in Eastern Mississippi to the Middle Chattahoochee River in Georgia . Within Georgia , this crayfish is only found in Quitman County .

Conservation Status

Procambarus acutissimus is listed as rare in Georgia and is threatened by pollution and habitat destruction within its limited range within the state.

Similar Species

Due to the high variability in its appearance, this species is usually difficult to identify. Accurate identification relies upon subtle anatomical features that are usually best recognized by trained professionals.