Species Information

Zebra (left) and quagga mussels Zebra (left) and quagga mussels
Zebra (left) and quagga mussels
Zebra mussel
Dreissena polymorpha

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Similar Species
  • Quagga mussel Dreissena bugensis

  • 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

  • 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


  • 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 

  • 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

Zebra mussels (Dreissena polymorpha)
Whitney Cranshaw, Colorado State University

Protecting the marine and freshwater resources of the Northeast from invasive aquatic nuisance species