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Zebra Mussel

Dreissena polymorpha

Young zebra mussels often settle on top of older, bigger mussels, creating large colonies. (Dan Minchin/Public Library of Science)
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Young zebra mussels often settle on top of older, bigger mussels, creating large colonies. (Dan Minchin/Public Library of Science)

The zebra mussel is a tiny bivalve with zebra-like stripes on its triangular shell. It lives in freshwater lakes, rivers, streams and reservoirs in parts of the Chesapeake Bay watershed. It is a non-native and invasive species.

Appearance:

  • D-shaped or triangular shell is patterned with dark (usually brown) and light stripes  
  • Flattened bottom allows zebra mussel to stand up straight on a flat surface 
  • Usually grows to less than one inch long 

Habitat:

  • Lives in still or slow-moving freshwater lakes, rivers, streams and reservoirs
  • Uses thin, strong threads to attach to solid, underwater surfaces, including rocks, pilings, pipes, buoys, boat hulls and native freshwater mussels and clams, limiting their ability to move and often smothering them 

Range:

  • Found in the Upper Bay and in parts of the Susquehanna River and its tributaries in New York, Pennsylvania and Maryland 
  • Native to the Black, Caspian and Azov seas in Eurasia 

Feeding:

  • The stationary filter feeder draws in water through a siphon in order to filter out plankton and other food particles
  • Unusued particles are ejected through a second siphon 

Predators:

  • Predators include crayfish, sturgeons, yellow perch, blue crabs and diving ducks 

Reproduction and Life Cycle:

  • Spawn once water temperatures warm in spring and summer 
  • Females can release more than one million eggs into the water in a single spawning season 
  • Free-swimming larvae drift in the water for a few months, during which time currents transport them throughout river systems 
  • Larvae anchor themselves to hard surfaces with thin, strong threads secreted from a gland on the foot
  • Young often settle on top of older, bigger mussels, forming large colonies
  • Typically lives three to nine years, although some can live as long as 15 years 

Other Facts:

  • Introduced to the Great Lakes region in the mid-to-late 1980s, likely via ballast water from a European ship. From there, zebra mussels spread rapidly throughout the United States
  • Zebra mussels can cause environmental and economic harm, killing native freshwater mussels and disrupting aquatic ecocystems as well as clogging municipal pipes and damaging boats  

  • It is critical that people help stop the spread of zebra mussels by cleaning boat hulls, trailers and other equipment before they are moved to a new body of water 

Sources and Additional Information:




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