The Cracking Pearlymussel
) is an endangered species
. While this species was originally distributed in the Ohio, Cumberland and Tennessee river systems, it has been extirpated from most of its previous range. Parmalee and Bogan reported that there were still populations in the Clinch River
in Tennessee. Other populations that are known to survive are located in the Powell
These mussels have thin, fairly strong, elongated shells. They may reach up to 90 mm (3.6 in). The outer coloring of the shell varies from yellow to brown, while the interior of the shell is pale bluish white with a purple beak cavity.
This species spends its adult life buried under the sand or mud in the bottom of medium-sized, flowing rivers. The females capture sperm released into the water by males. They store the sperm until they need them to fertilize their eggs. After fertilization, the females release the larvae into the river where the larvae attach to fish. Once the larva mature into juveniles with shells, they leave their host fish and drop to the sediment where they bury themselves. This process, therefore, requires an environment with ample fish to act as hosts. They prefer relatively shallow (usually less than 2 ft. deep) water with a moderate current.
The main threats to the continued existence of this species are habitat changes due to damming
of rivers, silting
of rivers due to erosion caused by construction, farming and logging, and poisioning due to agricultural and industrial pollution
. The U.S. Fish and Wildlife Service has created a recovery plan for this species.