California Aquatic Invasive Species (AIS)
University of California
California Aquatic Invasive Species (AIS)

Invasive Clams, Mussels, Snails, etc.

False Dark Mussel

Scientific Name

Mytilopsis leucophaeata - Visit ITIS for full scientific classification. 



  • Very similar in appearance and often confused with zebra mussels.
  • Can be distinguished by examining internal shell structure for tooth-like projection called apophysis. 
  • Found on hard surfaces, and usually in brackish (somewhat salty) water habitats. 
Invasion Pathways and Distribution
  • Native to the East coast and Gulf of Mexico.
  • Potential for introduction to California. 
  • Continue to spread by attaching to boats, trailers, fishing and other gear, as well as microscopic larvae potentially spreading in water either found in moving vessels, or when water is transferred between streams or lakes in a canal. 
  • Can survive out of the water for extended periods of time, and small juveniles are difficult to detect. 
Life History
  • Individuals are either male or female, with external fertilization.
  • Spawning events release microscopic larvae into the water column.
  • Multiply and reach densities that clog water delivery systems.
  • Filter water, removing plankton needed by native species, and changing water clarity.
  • Microscopic young stages can be transported in water undetected.
References and Useful Links

For references by category and links to other useful AIS sites see our LEARN MORE page.

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