Freshwater Mullusks

Mollusks are soft bodied animals most of which are enclosed in a hard shell. The exceptions are the marine octopuses, squids and land slugs. The shells are made mostly of lime secreted by the mantle. The mantle is the fleshy tissue that surrounds the animals body.

There are two main classes in fresh water; Gastropoda (snails and limpets) which have a single coiled structure and Bivalvia (clams) which have two hinged valves.