Dreissena polymorpha

Zebra Mussels are fingernail-sized mussels that were introduced from Europe through the St. Lawrence Seaway and into the Great Lakes in 1988. They have subsequently spread to most inland lakes and waterways in our area. Zebra Mussel colonies clog water systems of power plants, water treatment facilities, and irrigation systems, and can reduce or eliminate native mussels.

Zebra Mussels are usually less than an inch long and look like small clams with dark and light colored stripes. They are usually found in water less than 30 feet deep that is rich in algae. Adult female zebra mussels can produce up to a million eggs per year. After hatching, the free-living larvae begin to form shells and will subsequently attach to any firm surface under water, such as rocks, metal, wood, boats, native mussels and mollusks. Zebra Mussel larvae can be spread to other bodies of water in livewells, bilge water, and personal watercraft. Adults can attach to boats or boating equipment that sit in water and are then taken to another body of water.

Lake-wide control of Zebra Mussels is not feasible because chemicals that kill it also kill other aquatic life forms, mainly native species. Diving ducks eat Zebra Mussels, but because of the high reproduction rates of the exotic species, biological control is ineffective.

more info: http://www.aphis.usda.gov/lpa/pubs/invasive/8zebramu.html