(Mussels are from the ISM Collection)
Washboard Mussel (Meganonaias nervosa)
The bumps and ridges on the thick-shelled washboard mussel shell help anchor it ino the river bottom's sand and mud. Without these, the mussels could be washed loose and carried downstream.
Other mussels such as the giant floater are found in standing water,
where there is little chance that they will be
dislodged by waves or currents. Their shells are thin and smooth, not specially
adapted for life in flowing water.
Giant Floater (Pyganodon grandis)
