Endangered Species
Midwest Region



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Plethobasus cyphyus



As a group, mussels are long-lived, with individuals surviving up to several decades, and possibly up to 100, and even 200 years.  Sheepnose, especially thick-shelled individuals from large rivers, are thought to live longer than other mussel species, however, we have no age information. 

Photo by USFWS; Kristen Lundh

The sheepnose is a freshwater mussel found across the Midwest and Southeast.  However, it has been eliminated from two-thirds of the total number of streams from which it was historically known. Today, the sheepnose is found in Alabama, Illinois, Indiana, Iowa, Kentucky, Minnesota, Mississippi, Missouri, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.


The sheepnose is a medium-sized mussel that grows to about 5 inches in length. It lives in larger rivers and streams where it is usually found in shallow areas with moderate to swift currents flowing over coarse sand and gravel. 


Sheepnose Listed as Endangered


News Release:

U.S. Fish and Wildlife Service Lists Two Freshwater Mussels as Endangered (March 12, 2012)


Federal Register Final Rule: Determination of Endangered Status for the Sheepnose and Spectaclecase Mussels Throughout Their Range


Sheepnose Fact Sheet (March 2012)


Questions and Answers: Sheepnose and Spectaclecase Mussels Listed as Endangered (March 2012)


Status Assessment Report for the sheepnose, Plethobasus cyphyus, occurring in the Mississippi River system (September 2002) - - 79-page PDF; 712KB


Information about the Spectaclecase (the mussel listed as endangered in the same package as the sheepnose)



Midwest Endangered Species Home



Last updated: October 10, 2018