The pink mucket is an endangered native mussel that lives in flowing waters of large streams among gravel and cobble. In Missouri, it lives primarily in the Meramec, Gasconade, and Black rivers, and stretches of the Osage River.
Externally, the pink mucket's shell is thick, inflated, and smooth, rounded to slightly elongated. In males, the posterior end is bluntly pointed, making the shell appear round. In females, the shells may be nearly square. Growth-rest lines produce ridges and dark-stained grooves. The umbo (beak) is slightly raised above the hinge line. The beak sculpture, which is often difficult to discern, consists of 6–10 fine, wavy, double-looped bars. The periostracum (thin outer layer) is yellowish brown to chestnut in mature individuals. Broad, faint, green rays may cover the shell but are usually absent from adult shells.
Inside the shell, the beak cavities are deep. The pseudocardinal teeth are stout, triangular, and erect; the lateral teeth are long, curved, and sharp. The nacre (mother-of-pearl layer) is white to a light salmon or pink, commonly salmon to orange in the beak cavities.
For a fuller introduction to Missouri’s native freshwater mussels, and to learn the terms for their anatomy, see their group page.
Similar species: The mucket, plain pocketbook, and Higgins eye (Lampsilis higginsii) are similar.
Adult length: 3–5 inches.
In Missouri, the pink mucket lives primarily in the Meramec, Gasconade, and Black rivers, and stretches of the Osage River.
Habitat and Conservation
Pink muckets live in the large stream reaches where flowing water covers beds of cobble, gravel, and sand. The depth of the water can vary from one inch to five feet deep.
Because mussels are so intimately connected with their aquatic environment, drawing water in and out of their bodies, they are extremely sensitive to pollution and changes in water quality. Conservation efforts include habitat protection and improvement, and zebra mussel control.
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
Listed as endangered by both the Missouri Department of Conservation and the U.S. Fish and Wildlife Service. Current threats include loss of habitat, competition from invasive, nonnative zebra mussels, overharvesting, and illegal collection.
Life Cycle
Under certain conditions, males release sperm directly into the water. Females living downstream siphon the sperm into the gill chamber, where eggs are fertilized. The eggs mature into larvae, which eventually discharge into the water and attach to a host fish. Eventually, the tiny mussel breaks away and floats to the bottom of the stream. Each mussel species parasitizes only certain species of fish. For pink muckets, the host fishes are limited to the black basses (in genus Micropterus: the smallmouth, largemouth, and spotted basses), plus walleye and freshwater drum.
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. 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.
