Pleurobema plenum





On June 14, 1976, the rough pigtoe mussel was designated as endangered throughout its entire range in Alabama, Indiana, Kentucky, Pennsylvania, Tennessee, and Virginia (USFWS 1976). A recovery plan addressing the rough pigtoe was approved August 6, 1984 (USFWS 1984).



The rough pigtoe is a medium-sized (reaching up to approximately 100 mm in length) freshwater mussel with a yellowish brown or light brown shell (becoming dark brown in adults) with faint green rays (NatureServe 2003, INHS 1997). Like other freshwater mussels, the rough pigtoe feeds by filtering food particles from the water column. The specific food habits of the species are unknown, but other juvenile and adult freshwater mussels have been documented to feed on detritus, diatoms, phytoplankton, and zooplankton (Churchill and Lewis 1924). The diet of rough pigtoe glochidia, like other freshwater mussels, comprises water (until encysted on a fish host) and fish body fluids (once encysted).



The reproductive cycle of the rough pigtoe is similar to that of other native freshwater mussels. Males release sperm into the water column; the sperm are then taken in by the females through their siphons during feeding and respiration. The females retain the fertilized eggs in their gills until the larvae (glochidia) fully develop. The mussel glochidia are released into the water, and within a few days they must attach to the appropriate species of fish, which they parasitize for a short time while they develop into juvenile mussels. The rough pigtoe is likely a short term brooder with spawning occurring in the spring and release of glochidia during summer months (ESIE 1996, USFWS 1984). Specific glochidial hosts for this species are not known (ESIE 1996).



This species was historically known from the Ohio, Cumberland and Tennessee River drainages in Alabama, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia; however, the species is now believed to be extirpated from Pennsylvania, Ohio, West Virginia, Virginia, and Illinois. The species currently is known to survive downstream of three Tennessee River mainstem dams (Pickwick, Wilson, and Guntersville) and in the Clinch River (between river miles 323 and 154) (NatureServe 2003). In 1984, the rough pigtoe was also reported in the Green River in Kentucky (below locks 4 and 5) and in the Barren River (below lock and dam 1) (USFWS 1984).



The rough pigtoe is found in medium to large rivers with sand, gravel, and cobble substrates (USFWS 1984, ESIE 1996, NatureServe 2003). The species has also been reported from flats, and muddy sand in shallow waters (NatureServe 2003).



Many of the historic populations of the rough pigtoe were apparently lost when the river sections they inhabited were impounded (ESIE 1996). It is believed that establishment of the Green River dam, which was completed in 1969, may ultimately lead to the loss of the rough pigtoe population on that river (if it still exists). In addition, acidic drainage from mines on tributaries to the Cumberland and Tennessee Rivers is believed to be responsible for declines in the mussel populations inhabiting those waters. A portion of the Green River below Greensburg, KY has been affected by oil brine pollution which has eliminated nearly the entire mussel population that was once located there (ESIE 1996). Other threats that are attributed to population declines are similar to those described in the general mussel description.



Current threats to freshwater mussels are well documented in the general mussel description.





Exposure Scenario Summary Table for the Rough pigtoe




Life Stage


Habitat Type


Exposure Route




Significant Interspecies Relationships


rough pigtoe





contact with water, diet


water (until encysted), fish body fluids (once encysted)





juvenile / adult


sediment dweller


contact & ingestion of water, diet, sediment


filter feeder (bacteria, algae, detritus, sediment)







Churchill, E.P., Jr., and S.I. Lewis. 1924. Food and feeding in freshwater mussels. Bull. U.S. Bur. Fish. 39: 439-471.


Endangered Species Information Exchange. 1996. Species Id ESIS404019. Virginia Tech Fish and Wildlife Information Exchange. Available (Accessed: December 5, 2003)


Illinois Natural History Survey. 1997. Species Account, Pleurobema plenum Rough Pigtoe. Available (Accessed: December 5, 2003).


NatureServe. 2003. NatureServe Explorer: An online encyclopedia of life [web application]. Version 1.8. NatureServe, Arlington, Virginia. Available (Accessed: December 5, 2003 ).


U.S. Fish and Wildlife Service. 1976. Endangered Status for 159 Taxa of Animals. Federal Register 41: 24062-24067.


U.S. Fish and Wildlife Service. 1984. Recovery Plan for the Rough Pigtoe Mussel, Pleurobema plenum (Lea, 1834). Region 4. Atlanta, GA. 51 pp.