Quick Facts

Species Type



One to two inches long


Attach to shells, rocks and other hard surfaces using strong, thin fibers made from proteins called byssus threads. They grow prolifically on oyster reefs, often “wrapping up” oysters.


Found throughout the Chesapeake Bay and its rivers, but reach maximum size and greatest abundance in waters with low salinity


Filter feeder; feeds on plankton

Conservation Status



The hooked mussel is small, generally reaching one to two inches long. Its shell surface has distinct ridges and curves, and has a dull-colored black or gray exterior with a shiny purple or rosy brown interior. The front end of its shell is strongly curved, or “hooked.”


Hooked mussels are filter feeders that open their shells during high tide, drawing in water and filter food particles over their gills.


Predators of hooked mussels are primarily seaducks, such as scoters and goldeneye.

Reproduction and Life Cycle

As hooked mussels reach sexual maturity, their mantle will turn either bright yellow or stippled brown in color. Spawning occurs from June to October. Free-swimming larvae drift in the water for a few months, eventually anchoring themselves on hard surfaces as they mature into adults.

Did You Know?

  • Research suggests that hooked mussels can more than double the overall filtration capacity of an oyster reef. Hooked mussels also filter picoplankton, the smallest type of marine plankton, twice as effectively as oysters.
  • Hooked mussels can actually move by pulling themselves along on their byssus threads—releasing some and reattaching others—although this is a very slow process and they do not move very far.

Sources and Additional Information