The bleufer's shell is stout, inflated, oval to rectangular, and thick with a posterior wing; the anterior end is round; the posterior ridge is broadly rounded; the posterior end is bluntly squared (in females) to sharply rounded (in males). The umbo (beak) is broad and raised above the hinge line. The periostracum is smooth and glossy, dark brown, becoming black with age; young individuals have dark green rays that later fade.
Inside the shell, the beak cavity is broad and deep; the pseudocardinal teeth are relatively small, roughened, and pointed; the lateral teeth are prominent, bladelike, and slightly curved; the nacre (lining) is pinkish purple to deep purple.
For a fuller introduction to Missouri’s native freshwater mussels, see their group page.
Similar species: The pink heelsplitter is lighter in color and less inflated or stout, and its nacre is lighter in color. The pink papershell and plain pocketbook are also similar.
Adult length: 3–8 inches
Restricted to the Mississippi Lowland region in flood control ditches and in White, Black, St. Francis, and Mississippi river tributaries.
Habitat and Conservation
Medium to large rivers with reduced current in a stable mix of mud and silt or mud and gravel.
Food
Freshwater mussels consume algae, bacteria, and fine particles of decaying organic matter. They extract nutrients and oxygen from water drawn into the body cavity through a specialized structure called the incurrent siphon; sediment, undigested food, and waste (called pseudofeces) are expelled through the excurrent siphon.
Status
Common but restricted.
Life Cycle
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, the freshwater drum. The tiny mussel eventually breaks away and floats to the bottom of the stream, and the cycle repeats.
Human Connections
Mussels play important roles in maintaining the health of Missouri’s water resources:
- As food for fish, they are important for Missouri’s fisheries. Small mammals and some birds eat them, as well.
- They filter algae, bacteria, and other particles from the water, improving water quality and cycling nutrients and energy in streams and lakes. Clean water is necessary for people and nature.
- Because mussels are sensitive to habitat disturbance and pollution, they are good indicators of the overall health of aquatic ecosystems and water quality.
The shells of several types of mussels were an important resource historically for button manufacture. Because of its purple (not white) nacre, the bluefer was not used in the button industry.
Some species are still commercially important in the cultured pearl and jewelry industries.
Ecosystem Connections
Native freshwater mussels provide vital functions in aquatic ecosystems:
- They are an important food source for many species of fish, wildlife, and other invertebrates.
- Their shells, both while the animal is alive and after it dies, provide habitat for other organisms.
- As filter feeders, individual mussels can filter a significant amount of water per day, but not all of what they remove is eaten. What they don’t eat is combined with mucus into packets. These pseudofeces packets are eaten by some fish and invertebrates.
Freshwater mussels depend on healthy populations of certain types of fish to complete their life cycle. Although as larvae they temporarily parasitize these fish, the harm to the fish is negligible.
