Mussel Fact:
Mussels are bivalves, having two equally shaped shells linked together on one side by a hinge structure. Like most bivalves, mussels are filter feeders. They eat by pumping water through a set of gill filaments which filter out small particles such as phytoplankton, zoo plankton and other organic material. Sediment is discharged while food is retained and passed into the stomach where it is digested. Mussels are able to obtain all of their nutritional requirements from the natural environment and do not require additional feeding.
Mussels are the most efficient feeders of all shellfish, containing one-third more protein than oysters. A mussel will filter 10-15 gallons of water a day, consuming virtually everything in it.
Source: Mussel Facts