Mussels and Clams

Benthic Macroinvertebrates

Sensitive Benthos

Moderately Tolerant Benthos

Pollution Tolerant Benthos

Pond Mussel

Description:

Include the larger pearly naiad mussels, as well as the small fingernail clams, and the European clam (Corbicula). Mussels are large (up to 9 inches in diameter, robust, thick- or thin-shelled, and usually dark in color. Fingernail clams are small (no more than 1/2 inch in diameter), fragile, and are whitish or grayish in color. Corbicula can be larger, 1 to 2 inches in diameter, and light-colored.

Reproduction:

females deposit eggs on top of water where they drift to the bottom.

Adults:

fingernail clams are self-fertilizing, the young developing inside the water tubes of the adult; mussels have a very elaborate and intriguing process; the larvae, called glochidia, develop inside the adult female and are released into the water where they eventually attach onto a host fish; then they parasitize the fish for about two weeks until they drop off and develop on the stream bottom into an adult.

Food:

primarily filter feeders; filter organic debris and plankton out of the water; preyed upon by numerous fish and mammals.

Scientific Name:

Asian Clam (Corbicula)

Class: Mollusca
Order: Pelecypoda

Indicator Role:

Mussels are sensitive to siltation and low dissolved oxygen. Fingernail clams and Corbicula are opportunistic and can be found in degraded conditions.

Information Source:

McDonald, B., W. Borden, J. Lathrop.1990. Citizen Stream Monitoring: A Manual for Illinois. Illinois Department of Energy and Natural Resources, ILENR/RE-WR-90/18. Springfield, Illinois.

Other Links:

Zebra Mussel colonizing a mussel shell (Illinois Natural History Survey)

Zebra Mussels colonizing a mussel shell

Field Guide to Freshwater Mussels of the Midwest in Illinois Natural History Survey's Mollusk Collection
America's Mussels: Silent Sentinels (USFWS)
Pouch snails, limpets and fingernail clams by the Lackawanna River Corridor ssociation
Clams and Mussels in Freshwater Benthic Ecology and Aquatic Entomology Homepage – S.M. Mandaville from the Soil & Water Conservation Society of MetroHalifax

Biological Indicators | Aquatic Biodiversity | Statistical Primer