Sheepnose (Bullhead)
Plethobasus cyphyus (Raf.)

Status: State Endangered (August 1, 1989).

Occurence: Occurs in the upper and lower reaches of the Wisconsin River as well as the Chippewa and the Flambeau Rivers.

Aid to ID: Elongated heavy, brown shell with several radial knobs on disc. The anterior end is rounded and the posterior end bluntly pointed. Epidermis is yellowish-brown in smaller shells and darker brown in older shells. Pseudocardinal and lateral teeth are heavy. The nacre is white. Length to 5 inches (12.7 cm).

Habitat: Found in large rivers with a rapid current where it lives on mud, sand or gravel bottoms in water 1-2 m. deep.

Management Considerations: Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around dams could help to protect this species.

The content for this page was originally presented in the Endangered and Threatened Invertebrates of Wisconsin, a free publication available by contacting the Endangered Resources Program.