The zebra mussel (Dreissena polymorpha) is a small bivalve mollusk native to the freshwater rivers draining the Caspian and Black Seas of western Asia. This species of shellfish, which gets its name from the dark brown stripes on its tan shell, was introduced into the Great Lakes of the United States and Canada and became established sometime between 1985 and 1988.

The zebra mussel was first discovered in North America in June of 1988 in the waters of Lake St. Clair. The introduction probably took place two or three years prior to the discovery, and it is believed that a freighter dumped its ballast water into Lake St. Clair, flushing the zebra mussel out in the process. By 1989 this mussel had spread west through Lake Huron into Lake Michigan and east into Lake Erie. Within three years it had spread to all five of the Great Lakes.

Unlike many...