This Identification Section was authored by: Dr. S. Jerrine
Nichols U.S. Geological Survey Great Lakes Research Center 1451
Green Road Ann Arbor, MI 48105 Zebra mussels are not the only
freshwater bivalve molluscs that are found in North America, nor
are they the only introduced species. Because of this, it is
important to be able to distinguish between zebra mussels and
members of the other two bivalve superfamilies that occur in
North American freshwater habitats. Zebra mussels, Dreissena
polymorpha, belong to the superfamily Dreissenacea. The quagga
mussel, Dreissena bugensis, is the other introduced dreissenid
bivalve in North America. D. bugensis and the native brackish
water bivalve, the false dark mussel - Mytilopsis leucophaeata,
are the two bivalves that are most likely to be confused with D.
polymorpha. If one examines the ventral shell margin and ventral
shell edge of the mussels, differences are visible. Zebra
mussels have a concave or flattened bottom and an acutely angled
shell margin. Both feat