There are around 1,000 species of freshwater mussels, with about 300 of those found in North America. In Ohio, you can find 80 different kinds of freshwater mussels.  

Mussels are shellfish that belong to a group called bivalves, which means their body is enclosed within a hinged shell. They can be found in both saltwater and freshwater environments. Mussels feed by filtering small particles from the water, which helps keep the water clean. They are also an important food source for many other animals, both in the water and on land. 

At the Columbus Zoo, we’re dedicated to the conservation of freshwater mussels, specifically through our participation in The Association of Zoos and Aquariums' (AZA) Saving Animals from Extinction (SAFE) program and the Watters Aquatic Conservation Center.

Scientific Name:

Conservation Status:

Size: Depending on the species, they tend to range from about 1 inch in length to 8 inches or larger. 

Weight: Varies depending on species. The larger freshwater mussels are capable of reaching about 5 pounds.

Freshwater musself from the Watters Aquatic Conservation Center
Nutrition
Freshwater mussels filter small particles from their environment to eat, which includes algae, bacteria, protozoans, and phytoplankton.
Current Range and Historic Range
They are found in freshwater on every continent except Antarctica. About one-third of all freshwater mussel species reside in the United States.
Habitat
Freshwater mussels can be found at the bottom of most freshwater environments, which include lakes, ponds, rivers, and streams. It is also important that their environment be inhabited by fish.
Predators and Threats
Freshwater mussels are an important food source for many species of wildlife, including mammals, birds, and fish.

Freshwater mussels are known to be very sensitive to environmental changes. They can be affected by pollution, dams, sediment runoff, overcollection, and invasive species.
Physical Description and Adaptations
Freshwater mussels consist of two shells held together by a hinge and ligament. They have a large foot for burrowing and locomotion, and their gills for breathing, reproduction, and filter feeding. Some species develop a lure to attract fish and become hosts to their larvae.
Reproduction
Male mussels release sperm into the water, which may enter the openings of female mussels of the same species. Females will transfer fertilized eggs into their gill chambers, where they transform into larvae called glochidia. Once the glochidia grow enough, they must attach to a fish's gills or fins to continue changing into free-swimming mussels.

Glochidia can attach to fish in different ways. Some glochidia are light and float in the water after they're released, which means fish might accidentally "eat" them. Instead of going into the fish's stomach, these glochidia attach to the fish's gills. Others are heavier and sink to the bottom of the stream, where they are likely to stick to a fish's fins.

Certain species of female mussels use tricks to attract fish hosts before they let go of their glochidia. Their mantle tissue changes to look like small fish or insects. When the female moves these tissues, the fish might try to catch the "prey" and get a mouthful of glochidia instead. Other mussels use a special bait called a conglutinate, a gelatinous mass containing glochidia. Some mussels release this conglutinate into the water or let it sit on the stream bottom. It looks like a worm or insect, which the fish might eat. Other species keep the conglutinate attached to them by a "fishing line," allowing it to wave in the water and attract fish.

Once the glochidia successfully attach to a fish, they stay there for a time, depending on the mussel species. While attached, they change into juvenile mussels, developing essential parts such as the heart, liver, digestive tract, and muscular foot. When they finish their transformation, the young mussels leave the fish host.
Behaviors
Adult freshwater mussels are mostly sedentary and lack a central nervous system, but juveniles can burrow into sediments.