The zebra mussel (Dreissena polymorpha) is a small freshwater mussel. This species was originally native to the lakes of southern Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic (Black Sea) and Caspian (Caspian Sea) species. However, it has been accidentally introduced in many other areas, and has become an invasive species in many different countries worldwide.