Zebra mussel

Dreissena polymorpha (Pallas, 1771)

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

Other common names: None.

Key characters: Relatively 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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