Click to Enlarge Listen to Captions (168 KB) Disappearing Freshwater Mussels Snuffbox (top left) Four mussels— snuffbox, elephantear, ebonyshell and sheepnose—are listed as state endangered in Missouri. Elktoe (top right) Although not listed as endangered, the elktoe is one of many Missouri species with a declining population. The scaleshell (bottom left) and pink mucket (bottom right) mussels are listed as endangered both in Missouri and nationwide, along with the Curtis pearlymussel, Higgins eye, fat pocket and winged mapleleaf.   Mussel Power adapted by Joan McKee from Missouri's Freshwater Mussels Silent aquatic creatures are on the front line in the battle to keep Missouri's streams clean. Listen to "Mussel Power " (1.3 MB) Missouri’s freshwater mussels are efficient water filters. One mussel may filter several gallons of water a day. They draw water into their bodies through the incurrent siphon. Mussels digest algae and other small food suspended in the water. Gills extract oxygen to breathe. Sediment and waste is removed through the excurrent siphon. The waste is eaten by other aquatic animals. The mussel’s body is mostly a long, muscular foot that withdraws into the shell if it is pulled from the stream bottom. If you want to learn how to identify mussels, you can usually find plenty of empty shells around the bank of a stream—often left over from a raccoon’s midnight snack. The best way to observe live mussels is by snorkeling or scuba diving. If you find some, do not disturb them. Mussels may suffocate if they are placed back in a stream bed upside down—with their siphons buried in the rocks or mud. If you find a mussel that has been pulled from the stream bed, place it close by in the same habitat, on its side, behind a boulder or in quiet water. It will use its foot to rebury itself. Perils of Pollution Freshwater mussels are found in groups called mussel beds. Sometimes the beds can be a mile or more long with thousands of mussels. Adults bury themselves in the bottom of streams and lakes. In a clean stream, mussels can live a peaceful, long life—usually in the same area of the stream. Some mussel species can live as long as a human. But when streams become polluted, mussels are often the first to suffer. In unprotected streams, pesticides and fertilizers gradually build up in their bodies. Because of this, scientists study mussels to see how much pollution has been in the water over a period of time. When there’s too much pollution for long periods of time, mussels die. Mussels face many other problems. Too much dirt suspended in the water can make adult mussels stop feeding. Young mussels, some about the size of the period at the end of this sentence, can get smothered by these sediments and quickly die. Erosion and floods can carry dirt into streams. Freshwater mussels also need a stable habitat of rocks and sand. If too much water suddenly flows into a stream, the mussels could be rushed downstream to a habitat where they can’t easily survive. Dangerous times Native mussels are disappearing throughout North America. Exotic mussels are taking over their habitat, and poachers sometimes clean out entire mussel beds to sell to the jewelry industry. Of Missouri’s 65 mussel species, more than 10 are listed as endangered at the state or federal level. About half of them are listed as species of conservation concern. This means they could become endangered if they lose more habitat. Hatcheries help To help mussels survive, the Missouri Department of Conservation, U.S. Fish and Wildlife Service and Missouri State University are raising endangered mussels and putting them back in streams. They are also working with other groups to clean up Missouri’s waters so mussels will have the habitat they need. Life Cycle of a Mussel Listen to "Life Cycle of a Mussel " (512 KB) Missouri’s freshwater mussels trick fish into helping raise their young. Step 1: During the breeding season, male mussels release sperm into the water and the females filter the sperm into their gill chambers. The female’s gills incubate the fertilized eggs until they develop into tiny larvae, called glochidia. Step 2: Glochidia must attach to the gills or fins of a specific fish species. Mussels have unusual tricks to attract their host. Pocketbook mussels have a lure that looks like a small fish, while other mussels release their glochidia in packets disguised as insects or tiny fish. Host fish are fooled and try to eat the lures, taking glochidia into their mouths and gills. They stay in the fish for several days or weeks. Unlike other parasites, glochidia usually do not harm the host. Step 3: When mature, the tiny mussels release from the fish and drop onto the stream floor. Step 4: If the mussels drop into good habitat, they grow into adults and the cycle is repeated. Some mussel species live less than 10 years, while others live 20 to 40 or as many as 100. Spectaclecase Lilliput Pistolgrip Butterfly Pimpleback Pondmussel Deertoe Pink Heelsplitter Click to Enlarge Missouri Mussels Listen to "Missouri Mussels" (1.1 MB) In the early 1900s, mussel shells were used to make buttons for clothing. As a result, mussels were harvested faster than they could reproduce. In the 1940s, factories began using plastic for buttons, and mussel populations started to recover. The fishermen who harvested the mussels for the button industry gave many of the mussels their unusual names. Today, some mussel shells are used to make cultured pearls for jewelry. Spectaclecase: adult size 5-8 inches These mussel shells are similar in shape to an eyeglasses (or spectacles) case. These mussels live in large groups—as many as 100 mussels per square yard. They live in rivers among boulders or in patches of gravel and sand in slower current next to swift water. They often live more than 60 years. Lilliput: adult size 1-2 inches Missouri’s smallest native mussels get their name from the book, Gulliver’s Travels. The tiny people in the book are called Lilliputians. These mussels prefer to live in large rivers with slow or no current. Their beds are in silt, sand or small gravel. Also look for them in ponds and lakes. Pistolgrip: adult size 4-7 inches These mussel shells are shaped like the handle of a gun. Look for these mussels in rivers with stable beds of gravel, sand or mud in moderate current. Butterfly: adult size 3-5 inches These hard-to-find mussel shells, when opened up, look like a butterfly in flight. The mussels live in coarse gravel and sand in large rivers with strong current. Pimpleback: adult size 2-3 inches The shell of the pimpleback is usually bumpy. These mussels can be found in small to large rivers in beds of coarse gravel and sand or mud. Pondmussel: adult size 2-4 inches These mussels are named after the place they prefer to live. Also look for them in lakes and quiet waters of creeks and rivers in silt, mud or sand. Deertoe: adult size up to 3 inches You might see these mussel shells along medium to large rivers. Shaped like a deer’s hoof, these mussels can be found in moderate to swift current in gravel mixed with sand and mud. Also look for decorative green markings on the shells. Pink Heelsplitter: 3-8 inches It’s not difficult to see how this mussel got its name. You wouldn’t want to step on its sharp edge (called a dorsal wing) while wading barefoot in a stream. These mussels can be found in medium to large streams. Their beds are usually made up of either mixed sand and mud or sand and gravel. If you want to know more about identifying Missouri’s mussels, go to: mdc4.mdc.mo.gov/Documents/168.pdf to download a copy of Missouri’s Freshwater Mussels by Sue Bruenderman, Janet Sternburg and Chris Barnhart. Also visit http://unionid.missouristate.edu to view Chris Barnhart’s upclose photos and videos of mussels.