Species Information

Zebra mussel
Dreissena polymorpha

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Similar Species

• Quagga mussel Dreissena bugensis

History

• Believed to be introduced to the Great Lakes during ballast water exchange from a cargo ship from the Black Sea
• Since being discovered in Great Lakes in 1988, the species has spread widely into freshwater habitats across North America
• Native to Black, Caspian, and Azov Seas

Characteristics

• Named for the striped pattern on its shell - Black or brownish shell with cream or white stripes
• Shells colors vary widely; some pale or completely white
• Maximum size less than 2 in (5 cm) long; often less than 1 in
• Zebra shell is stable when placed on it's flattened hinge side while quagga mussels, lacking a flat side, fall over
• Valves (shell halves) are symmetrical, forming a straight line when closed whereas the quagga mussel valves are asymmetrical, forming a curved line when the valves are closed

 

Habitat

• Lakes, estuaries, streams
• Attached to hard surfaces such as rocks, wood, and plants and to manmade structures of concrete, metal, and fiberglass
• Tolerate salinity to 6 ppt, temperatures to approximately 29 degrees C

Known Distribution in the Northeast

• 21 states and 2 provinces including Quebec, New York, Vermont, Massachusetts, and Connecticut 

Impacts

• Voracious filter feeders, removing microscopic plants and animals from the water, reducing food available to other aquatic animals
• May cause declines in fish populations
• Clog intakes for power plants, industrial facilities, and public drinking water supplies
• Foul boat and ship hulls
• Economic impacts in the billions of dollars