[AR T&E Species Home]


To learn more about the life cycle and reproduction of mussels, click here.
For an interactive version, click here.

View the 2014 Spectaclecase Recovery Outline.


Spectaclecase (Margaritifera monodonta)
Status: Endangered
April 12, 2012

For questions regarding the Spectaclecase, please contact Chris Davidson at chris_davidson@fws.gov or 501-513-4481.

Species Facts:
The spectaclecase is a large mussel that can grow up to 9 inches in length. The shell is elongated and somewhat inflated, and sometimes curved, giving the species its name. The oldest documented spectaclecase was thought to be 70 years old.

The reproductive cycle of the spectaclecase is similar to that of other native freshwater mussels. Females retain fertilized eggs in their gills until the larvae (glochidia) fully develop. The glochidia are then released into the water, and attach to the gills of a specific species of host fish. They parasitize this fish for a short time while they develop before dropping off as juvenile mussels. The host fish for the spectaclecase is unknown.

Habitat Summary:
Spectaclecase is found in large rivers with swiftly-flowing water, usually among and under large boulders in patches of mud, sand, and gravel.

The spectaclecase is found in only 20 of 44 streams where it historically occurred.  With a few exceptions, spectaclecase populations are fragmented and restricted to short stream reaches.

Why is it Endangered?
Dams, reservoirs, and impoundments have flooded much of this mussel's habitat, and contributed directly to the extirpation of spectaclecase populations in some streams and resulted in the highly fragmented habitat and isolated populations currently seen in the species. Large dams also affect the flow and water quality downstream (reduced temperature, oxygen, and flow, and bank and substrate instability and erosion), which continues to negatively affects pink mucket populations.

As with other mussels, spectaclecase are also sensitive to water quality and sediment.

Many states that have spectaclecase populations are conducting surveys and funding research to find out more about this species and ways to improve its survival.

View the 2014 Spectaclecase Recovery Outline.

Range in Arkansas:

Arkansas Field Office
110 S. Amity Road
Suite 300
Conway, AR 72032

501/513 4470 (v)
501/513 4480 (f)

Last Updated: December 30, 2015

DOI |USFWS | USA.gov | Privacy | FOIA | Webmaster

FWS Southeast Region