how many known mollusks are there?
There are almost 100,000 species of mollusks around the world, and many tens of thousands more undiscovered. Most mollusk species only live in the ocean, but some live in freshwater or on land. In Michigan there are about 300 species of mollusks known, with more to be found. There are three main groups of mollusks. Snails ( Gastropoda ) are the most diverse group, there are tens of thousands of species.