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tarspiny.jpg - image of Tar Spinymussel
 
 
 
 

Tar Spinymussel in North Carolina

TAR RIVER SPINYMUSSEL

Elliptio steinstansana

STATUS: Endangered

DISTRIBUTION: Two relatively good populations are known to exist in two tributaries of the Tar River. Although they have been found in one other tributary, the main stem of the Tar River, individuals are becoming harder to find.  

DESCRIPTION, BIOLOGY, AND HABITAT: The Tar spinymussel, one of only three freshwater mussels in the world with spines, is a medium-sized mussel reaching about 2.5 inches in length. In young specimens, the shell's outer surface (periostracum) is an orange-brown color with greenish rays; adults are darker with inconspicuous rays. The inside of the shell (nacre) is yellow or pinkish at one end and bluish-white at the other. Juveniles may have as many as 12 spines; however, adult specimens tend to lose their spines as they mature. The Tar spinymussel lives in relatively silt-free uncompacted gravel and/or coarse sand in fast-flowing, well oxygenated stream reaches. It is found in association with other mussels, but it is never very numerous. It feeds by syphoning and filtering small food particles that are suspended in the water. 

Their method of reproduction is similar among freshwater mussel species. Males release sperm into the water column, and the sperm are taken in by the females through their siphons as they respire. The eggs are fertilized and develop within the females' gills into larvae (glochidia). The females release the glochidia, that must then attach to the gills or fins of specific fish species. The glochida transform into juvenile mussels and drop off the fish onto the stream bottom.  

Species Distribution from known occurrences. Species may occur in similar habitats in other counties.Green counties indicate observed within 20 years. Yellow counties indicate an obscure data reference to the species in the county. Red counties indicate observed more than 20 years ago.

Map of Species Distribution of the Tar SpinyMussel

Species Location Map based on information provided by the North Carolina Natural Heritage Program.
For additional information regarding this Web page, contact John Fridell, in Asheville, NC, at john_fridell@fws.gov

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