Illinois Natural History Survey - University of Illinois

Dreissena polymorpha (Pallas, 1771)

Zebra mussel


Dreissena polymorpha attached to Potamilus alatus, INHS 13808Dreissena polymorphaattached to Potamilus alatus, INHS 13808. Lake Erie, Ottawa County, Ohio.
Length: 0.8 inch (2.0 cm).

Other common names None.

Key charactersRelatively small, triangular, and elongate shells with alternating cream and brown bands on the surface.

Similar species Dark falsemussel. See Marsden (1992) for information on distinguishing between these two species.

Description Adults with a distinctively shaped, elongate, triangular, and inflated shell. Highly variable with respect to color as its scientific name polymorpha (many forms) indicates. Most are white or cream-colored with jagged lateral brown to black stripes or bands, which give the species its common name. Some have longitudinal bands, and all-cream or all-black individuals have been found. Length to 1.5 inches (3.8 cm).


No pseudocardinal or lateral teeth. A small shelf or septum present at the anterior end forming a moderately deep beak cavity. Nacre white and somewhat polished.

Habitat Lakes and streams of all sizes; attaches to rocks, freshwater mussels, or almost any hard surface by gluelike fibers called byssal threads.

Status Introduced into the Great Lakes from eastern Europe and rapidly spreading throughout the United States.

Distribution For current information about zebra mussels, click here.

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