Shell is thick, inflated, elongate with a pointed posterior end. Umbo is low and broadly rounded. Epidermis is shiny; younger mussels yellowish-green with fine green rays; adults straw-colored with faint or no rays, becomes darker with age. Inside shell beak cavity is moderately deep; pseudocardinal teeth thin, elongate, serrate and well-developed; lateral teeth long and straight to slightly curved; nacre (lining) white.
Similar species: Black sandshell has a very dark epidermis. Fatmucket shell is not as elongate and more inflated, typically with prominent rays.
Adult length: 3-6 inches.
Widespread, but absent from south-flowing streams in south-central Missouri.
Habitat and Conservation
Small to large rivers in slow to moderate current in sand, sandy mud or fine gravel; also ponds, sloughs and reservoirs.
Algae and fine particles of decaying organic matter; extracts nutrients and oxygen from water drawn into the body cavity through a specialized gill called the incurrent siphon; sediment and undigested waste are expelled through the excurrent siphon.
Common, although degrading water quality and watershed destabilization interfere with the survival of this and all freshwater mussels.
Males release sperm directly into water. Females downstream siphon sperm into the gill chamber, where eggs are fertilized. Eggs mature into larvae (called glochidia), which discharge into the water and attach to host fish—in this species, longnose gar and probably also other gars, sunfishes, largemouth bass and crappies. The tiny mussel eventually breaks away and floats to the bottom of the stream, and the cycle repeats.
Mussels are excellent indicators of water quality because they are long-lived and relatively immobile, accumulating contaminants in water that can be analyzed. Its large, white shell made this species very important for the button industry; its long, straight sides make it valuable for inlay work.
Mussels act as nature's “vacuum cleaners,” filtering and cleansing polluted waters. They are also an important food source for other species in the aquatic environment.