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Cambarus acanthura


Scientific Name:  Cambarus (Tubericambarus) acanthura Hobbs

Rarity Ranks:  G4G5/S3

State Legal Status:  None

Federal Legal Status:  None

Description:  The overall color of the Thornytail Crayfish varies from a dark greenish-brown to orangish-brown.  The edges of the rostrum are reddish or orangish and the tips of the claws are reddish.  The cephalothorax of this species is somewhat laterally compressed.  The claws of this species are fairly diagnostic; the mesial margin of the palm has at least three rows of tubercles.  The areola is virtually obliterated and there is a spine that extends beyond the edge of the mesial ramus of the uropod.  This species reaches a maximum total body length of about 78 mm (3.1 in).

Similar Species:  Within its range the species can be separated from all others by the multiple tubercle rows (3+) along the mesial margin of the palm combined with the spine extending beyond the margin of the mesial ramus of the uropod. 

Habitat:  Adults inhabit complex burrows adjacent to streams and ditches or in low areas where the water table is near the surface of the ground.  Hobbs (1981) collected young Thornytail Crayfish and females carrying eggs from streams.

Diet:  Crayfishes are considered opportunistic omnivores that will consume virtually any live or dead organic matter that they find or can capture.  Night video of burrowing crayfishes indicates they may also be active predators of invertebrates that venture close to their burrow openings.

Life History:  Male Thornytail Crayfish in breeding condition have been collected in April and May in Georgia and in June in Tennessee.  Females carrying eggs were found in April, and females with young were found in April and May (Hobbs 1981).  The smallest male in breeding condition is about 54 mm (2.1 in) and the smallest female with eggs is about 60 mm (2.4 in) in length (Hobbs 1981).

Survey Recommendations:  Burrowing crayfishes may be collected by direct excavation of their burrows, by trapping, and during night surveys.  Excavating burrows is time consuming and can be very difficult.  It also results in destruction of the animals’ burrow.  Traps made with PVC pipes or mist nets can be effective, but only when crayfishes are in an active period.  Burrowing crayfishes are sometimes captured around the openings of their burrows on damp nights.  It is possible to find active burrows from about mid-March to mid-November if the water table is within about 2 feet of the surface of the ground.  However, most activity is seen in the spring from mid-March to mid-May and the fall from mid-September to mid-November.  Since juveniles and females with eggs or young can be found in streams, surveys targeting this species should include looking under rocks and woody debris.

Range: In Georgia, the Thornytail Crayfish is known primarily from the northwestern portion of the state in the Coosa and Tennessee river systems.  It has also been found in the upper Ocmulgee River system and the Tallapoosa River system.  Outside of Georgia, it is found in southeastern Tennessee and northeastern Alabama.

Threats:  This species is apparently secure across its range.

Conservation and Management Recommendations:  Areas with burrows should be protected from land disturbing activities and activities that could alter groundwater resources.  Environmental education programs should include information about burrowing crayfishes and encourage protection of burrows.

Selected References:

Hobbs, H. H.,  Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1-549.

Taylor, C. A., G. A. Schuster, J. E. Cooper, R. J. DiStefano, A. G. Eversole, P. Hamr, H. H. Hobbs III, H. W. Robison, C. E. Skelton, and R. F. Thoma. 2007.  A reassessment of the conservation status of crayfishes of the United States and Canada after 10+ years of increased awareness.  Fisheries 32(8):372-389.

cambarus acanthura map bDate Compiled or Updated: August 2012

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