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As is true globally, invertebrates dominate Maine’s biota in terms of species richness and biomass. Based on available data, MDIFW estimates conservatively that Maine is home to over 16,000 species of terrestrial and freshwater invertebrates, from beetles and butterflies to mayflies and mussels, to name just a few.  Coordinating survey, research and conservation priorities for such a diverse suite of organisms is challenging! The best-studied phyla in Maine, as in most states, are the Mollusca (snails and mussels; ∼200 species).  Click here for The Freshwater Mussels of Maine.



As filter-feeders, freshwater mussels provide a vital service to Maine’s lakes, ponds, rivers and streams by removing suspended particles such as algae, bacteria, and detritus from the water column. Because they constantly filter large volumes of water, reside in the benthic substrate, can’t leave their surroundings, and live a long time (more than 100 years for some species!), freshwater mussels are sensitive to contaminants and changes in their environment. Consequently, they are a valuable indicator of water quality and aquatic ecosystem health, but they also are one of the most imperiled groups of animals in the country. Of the nearly 300 species of freshwater mussels found in the United States, more than a third have already vanished or are in danger of extinction and over 75% are listed as Endangered, Threatened, or Special Concern on a state level. These dramatic declines have been caused largely by the degradation and loss of mussel habitat from pollution, dams, and the channelization and sedimentation of once clean, free-flowing rivers and streams. In some parts of the country, the accidental introduction of a prolific foreign competitor, the zebra mussel, is also jeopardizing many populations.  Read more...


Chinese mystery snails, native to parts of Southeast Asia, were brought to this country as a food source for Asian markets. It is believed that imported snails were intentionally released in some ares to create a locally-harvestable supply. Since their introduction, Chinese mystery snails have spread to many parts of the United States, and can now be found in a number of Maine lakes and ponds.   Read more...

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