Where do mussels live?
Most freshwater mussels live in flowing water, in everything from small streams to large rivers .  A few species can live in lakes.  They are found across the U.S., but most of the diversity of species lives in the drainages of the Mississippi and Ohio River systems and in the Southeast United States.   

Mussels live on the stream bottom, often completely burying themselves in the substrate (photo) leaving only their siphons exposed.  They are hard to see because they blend in with the bottom and because any exposed part of the shell grows algae.  In good habitat, mussels will form dense concentrations called mussel beds (photo).  Mussel beds can have thousands of individuals sometimes reprensenting dozens of species all living in one place.

Crooked River at Smith Rocks State Park, Oregon Western Ridged mussel
Crooked River at Smith Rocks State Park, Oregon , home of the Western Ridged mussel
Photos, courtesy of Al Smith, Pacific NW Native Freshwater Mussel Workgroup

Eastern Pennsylvania stream Eastern pearlshell
Eastern pearlshell (Margaritifera margaritifera) stream in eastern Pennsylvania.
Photo credit:  Nevin Welte, Pennsylvania Fish & Boat Commission

Ecological benefits:

Mussels are food for fish, raccoons, river otters, mink and muskrats, and mussel beds actually create habitat for many other invertebrates. These invertebrates in turn serve as a food base, supporting fish and other animals in the aquatic ecosystem.  Because mussels release unwanted food items in a mucus strand, they transfer suspended food from the water column to the stream bed, making this food available for aquatic insects and other small animals. As filter feeders, they clean harmful bacteria and parasites from the water.