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Species Description

Alabama Creekmussel

Strophitus connasaugaensis


Classification

Phylum: Mollusca
Subphylum:
Class: Bivalvia
Order: Unionoida
Family: Unionidae

Description

The Alabama Creekmussel is a small to medium sized freshwater mussel. Adults typically measure less than 4.75 inches (120 mm) in length. This thin-shelled species has distinctive ridges that run parallel to its concentric growth lines. The periostracum (outer shell surface) is yellowish green in appearance and becomes a dull brown color with age. The nacre (surface of inner shell) is bluish-gray.

Life Cycle

Many of the specific details about the complex life cycle of this rare mussel are not currently known, but the life history of Strophitus connasaugaensis is presumed to be similar to related species. Male Alabama Creekmussels release sperm into shallow rivers. Sperm enters females through siphon-like regions and fertilization of eggs occurs within female shells. These fertilized eggs develop into special larva called glochidia. Glochidia continue to develop and are released into the water column when fully matured. The parasitic glochidia must find and attach to the gills or fins of the appropriate host fish to complete development. The required host species for the Alabama Creekmussel are not known at this time. The glochidia parasitize a fish host for a variable length of time, likely depending upon water temperature, fish species and other factors. Larvae transform into juvenile mussels on the fish and then release from the host to find a suitable substrate, often the fine gravel and sand bottom of a gently flowing, shallow river.

Natural History

Many of the details about the natural history of the Alabama Creekmussel are not currently known, but they are believed to be similar to better known, related species. Larvae (glochidia) are parasitic upon tissue of fish hosts while completing the metamorphosis into juvenile mussels. Adult mussels are typically sessile and are found attached or buried within the clay or sandy bottom of shallow rivers. Adults are typically found in shallow water that is less than 2 feet in depth. Adult mussels are filter feeders and usually feed upon plankton and detritus from their aquatic environment. Alabama Creekmussels bring water from their habitat into their shells through specialized regions that are similar to the true siphons of clams. The water is then filtered over its gills and food particles are trapped and eventually digested.

Range

The Alabama Creekmussel is found in gently flowing, shallow rivers within the Alabama River system within portions of Georgia , Alabama , Tennessee and Mississippi . Within Georgia , it may be found in portions of the Conasauga River and Coosa River drainages.

Conservation Status

This freshwater mussel is currently Rare within Georgia . Like many freshwater mussels, this species has presumably been adversely affected by habitat degradation, pollution and excess sedimentation.

Similar Species

Within its limited range in Georgia , Strophitus connasaugaensis is fairly distinct due to its combination of thin shell, growth line ridges and bluish-gray nacre.