North Carolina Wildlife Resources Commission

Slippershell Mussel (Rafinesque, 1820)

Scientific Name: Alasmidonta viridis

Classification:  State Endangered

Photo Credit: NCWRC




NOTE: Hover over the bold words for definitions or see the Glossary.

Rafinesque described the slippershell mussel in 1820 from the Ohio River. This species has a small, moderately solid, rhomboid shaped shell that rarely exceeds 55 mm in length. Shells are thicker towards the anterior end. The periostracum can be yellowish brown or light yellow, with wavy green rays; however, the periostracum on most adult specimens in North Carolina is dark brown. The nacre is bluish white or creamy beige, and the posterior margin may be slightly iridescent blue. Lateral teeth are indistinct and may be represented by a slight swelling along the hinge line. Each valve has one, stumpy pseudocardinal tooth. Sometimes, an additional, vestigial pseudocardinal tooth may be present in each valve.


Shell Anatomy

This species has a widespread distribution that includes the Upper Mississippi River Basin; Ohio, Cumberland and Tennessee River Subbasins; St. Lawrence River Basin; and Lake Huron, Lake St. Clair, and Lake Erie drainages in Canada.

Distribution by County: Little Tennessee River Basin: Swain Co. (Little Tennessee River Basin); French Broad River Basin: Henderson Co. (Mills River Subbasin). NOTE: All headwater areas that flow into these occupied habitats should receive special management.


This species has been found in a wide variety of habitats across its range. In North Carolina, the slippershell mussel inhabits riffle areas with gravel/cobble/boulder substrate. In other locations, the species has been found in small to large streams and lakes; substrates ranging from silt and sand to cobble; and slow to fast currents. It is often found in and around waterwillow, Justicia americana.

The slippershell mussel is a bradytictic brooder, with gravid females observed from fall through spring (Baker 1928, Clarke 1981, Zale and Neves 1981). Hermaphroditic individuals also have been found (Ortmann 1911). Identified fish hosts for this species include the banded sculpin, the mottled sculpin, and the johnny darter (Clarke 1981, Zale and Neves 1981).


General Life History For Mussels