Villosa iris

Villosa iris, the rainbow mussel or rainbow-shell, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. All Unionidae are known to use the gills, fins, or skin of a host fish for nutrients during the larval glochidia stage. Female villosa iris attract host fish by imitating a crayfish. Elongate papillae on the mantle margin resemble antennae, legs, and eyes. They also mimic crayfish behavior, moving the papillae independently like legs, and use 'tail tucking' motions. Juvenile mussels bury in the sediment just below its surface, and feed on interstitial bacteria and bacterial-sized particles including algae. This species is widely distributed throughout the St. Lawrence, upper Mississippi, Ohio, Tennessee, and Cumberland River Basins.