Zebra mussels are small, fingernail-sized animals that attach to solid surfaces in water. Adults are 1/4 to 1 1/2 inches long. They have D-shaped shells with alternating yellow and brownish colored stripes. One female zebra mussels can produce 100,000- 500,000 eggs per year! It is the only freshwater mussel that can attach to objects. They are native to Eastern Europe and Western Russia and were brought over to the Great Lakes in ballast water of freighters.
Zebra mussels can cause problems for lake shore residents and re-creationists. Homeowners that take lake water to water lawns can have their intakes clogged. Zebra mussels will attach to boats/motors, nets, docks, swim platforms, boat lifts, and can be moved on any of these objects. While mussel larvae can be present in bilge water and live wells, research shows that Zebra mussels are most likely to be transported by clinging to weeds.
Zebra Mussels were first discovered in the Great Lakes in 1988 and in Duluth/Superior Harbor in 1989. They have spread throughout the Great Lakes and the Mississippi River from Brained downstream, and are now in other rivers and inland lakes.
Zebra mussels are a prohibited invasive species which means import, possession, transport, and introduction into the wild is prohibited.
Zebra mussels are invading Minnesota's waterways and are currently found in at least 20 counties. The Minnesota Department of Natural Resources (DNR) calls these "prohibited invasive species" a threat to our environment and our economy. Minnesota 2020 went out with the DNR to learn more about these invasive invertebrates as they collected samples from Prior Lake in Scott County.
Juvenile zebra mussel, probably 4-5 weeks old and about 2-3 mm in size.
This is likely the smallest size that you will be able to see a zebra mussel.
Photos courtesy of Eric Fieldseth, AIS Consulting Services