Bivalvia are mollusks that have shells in two parts. They are all aquatic. Some can swim, dig, and filter-feed. They are found all over the world in both freshwater and saltwater.
Zebra Mussel (Dreissena polymorpha)
Zebra mussels are a small species of mussel, native to Russia. They are on the list of invasive species in many countries. The mussels clog up power turbines in hydroelectric plants. However they supply food for crayfish, muskrats and other aquatic mammals.
Giant sea clam (Tridacna gigas)
Giant sea clams are native to the Pacific and Indian oceans, they are 4 feet long and 440 lbs. The clam gets its nutrition from the algae that lives inside it.