Identified by the striped pattern on their shells, adult zebra mussels are usually less that 1 1/2 inches long. Their life cycle also includes a microscopic larval stage.
The freshwater, tidal Hudson River, as far south as Haverstraw, as well as in a few lakes and large rivers in the Hudson Valley. Adult animals attach to rocks, boat hulls, docks, pipes and other solid objects that are permanently submerged. Microscopic larvae float in the open water.
Zebra mussels entered the Great Lakes in the 1980s as a European stowaway in untreated ballast water. They spread into the Hudson River via the Erie Canal, or on the hulls of boats that were contaminated in Lake Erie.
Large colonies of zebra mussels divert food away from native river animals, including valued fish such as shad. They also attach to and smother native shellfish and foul water intake pipes and boat hulls.
Utilities keep animals out of their pipes using chemicals such as chlorine, polyquaternary ammonium compounds, or the recently developed bacterial toxin Zequanox. In natural settings there are not many feasible control options.
Female zebra mussels can produce up to a million eggs each year.