Freshwater mussels are some of the planet's most fascinating and underappreciated animals. With their beautifully colorful shells, diversity of shapes and interesting adornments — including ridges, bumps and spikes — they've earned intriguing common names like fuzzy pigtoe, purple wartyback, winged spike, fluted elephantear, spectaclecase, rough rabbitsfoot and orangefoot pimpleback. Freshwater mussels are culturally significant because they were harvested by American Indians and early pioneers for use as food, jewelry and tools. Before the development of plastic, buttons were made from mussel shells. Freshwater pearls are still cultured by inserting small pieces of native mussel shell into oysters.
Mussels are also fascinating because of their life histories, carried out on river bottoms. They are among the longest-lived invertebrates, surviving as long as 100 years. Their reproduction is complex and remarkable. Mussels, which cannot see, must make a lure that mimics a juvenile fish, worm, snail or insect to successfully attract specific fish, or in one case a type of salamander, to serve as hosts for their parasitic larvae. Mussel larvae develop into perfectly shaped tiny mussels on their host's gills before dropping off to begin lives on their own. Because mussels and their hosts have evolved together over millennia, they're fascinating to scientists and dilettantes alike due to the complexity of their relationships.
Mussels are also an indicator species of water quality and play an important role in rivers by filtering water constantly as they breathe and feed. They improve water quality by filtering out bacteria, algae and pollutants, but in doing so they accumulate contaminants in their bodies.
Mussels play a critical role in the food web because they perform this filtering service and convert an otherwise inaccessible energy source into food for animals that prey on them — fish, crayfish, amphibians, reptiles, birds and mammals. Mussel shells provide living space for insects and plants, and empty shells serve as nesting sites for small fish like darters.
Unfortunately, for all their allure, freshwater mussels are the most endangered group of organisms in the United States. Water pollution has wreaked havoc on these clean-water-loving animals, and dams have deteriorated water quality and separated mussels from the host fish on which their survival depends. Thirty-five species have already been declared extinct, and more are likely gone.
The Center is passionate about securing a future for these amazing animals. Our work has led to Endangered Species Act protection for 22 mussels, and three dozen more are under status review for federal protection.
We funded a natural history poster featuring the extinct freshwater mussels of the American Southeast to increase awareness and motivate actions to save the surviving species.
• Johann Boepple, the man who launched the U.S. industry of making buttons from freshwater mussel shells, died of an infection resulting from cutting his foot on a mussel called the pink heelsplitter.
• Only one species, the salamander mussel, relies on giant salamanders called “mudpuppies” to host its larvae. All other species have fish hosts.
• Some mussels package their fertilized eggs into gelatinous packets called “super conglutinates,” disguised as a tasty morsels for fish, that they extend on a string of mucus that can be several feet long.
• Other mussels can jump up and clamp onto a fish’s face to expel their larvae onto its gills.
• Worldwide there are 890 known freshwater mussel species, and 302 of those live in North America.