Fisheries Program
Northeast Region

Northern riffleshell (Epioblasma torulosa rangiana)

Life History

Riffleshell are found in packed sand substrate in riffles and runs. Females move eggs into the gill marsupial where they will be fertilized by sperm from males as water passes through the gills. Tiny larvae develop over days or months but if spawning is late, they may hold through winter. They are obligate parasites in that they need a host fish to complete their life cycle and to move within the watershed. We know that they can spawn from spring through mid-summer. Females display a white mantle-lining to lure hosts but the hosts remain unknown.


Historic range included the Maumee and Ohio River drainages. The largest remaining populations of Northern riffleshell are in the Allegheny River and French Creek, Pennsylvania. Its’ also seen in the Elk River in West Virginia.

Fun Facts

Listed as endangered on February 22, 1993.
Live for 15 or more years.
Grows to three inches in length.

More Information

Clubshell and Northern Riffleshell Recovery Plan (pdf - 3.69MB)

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Last updated: December 16, 2011
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