Mussels are slender blue-black bivalves that are found on both the Atlantic and Pacific coasts as well as other major waterways. There are saltwater mussels and fresh water mussels and even though very much alike in appearance, are they are considered to be different subclasses. When mussels are born, they are larvae. Hairy cilia help the mussels to swim. Cilia is hair-like strands that cover the mussel's body. The cilia take the water to the gills and the mussel gets oxygen from the water. The cilia also take the plankton to its mouth. On the second day of its life the mussel has a tiny yellow shell. When the mussel grows, it loses its cilia. The mussel floats for a month trying to find a place to settle. A bubble of air inside its body keeps it floating. The mussel is only 1/15 inch long when it settles to the bottom of the ocean. Mussels spend most of their lives in one spot. In the mating season the female mussel squirts millions of eggs into the water. As the male passes, he sends out many sperms. When mussels are young, they attach to the sea floor with strong threads called byssus. Byssus are rope-like strands that tie the mussel to the ocean floor. Pulling mussels off the rock is almost impossible, but sometimes these threads break and the mussel has to grow new byssus and attach to the rock again. The mussel filters fifteen gallons of water in one day. They filter two to three quarts of water an hour. They live in the mid and low tide zones.
Because mussels are severely affected by pollutants, they are now being commercially farmed in "safe" waters. When conditions are optimal, these cultivated mussels are usually superior in quality to wild mussels. Although available year round, mussels are best and most plentiful from October through May; in late spring, their spawning season, they tend to be of inferior quality. In their natural state, mussels attach themselves to surf-washed rocks and spend half their lives submerged and half exposed to the air. Mussels are sold live, fresh (shucked), and cooked as well as smoked. You can also buy canned mussels. When you buy mussels, it is imperative to keep them alive--or cold--until you are ready to cook and serve them. Mussels, because they are sold live, offer specific signals of freshness: the shells should be tightly closed (pulling mussels from the shell destroys them), or should close tightly when the shell is tapped; don't buy mussels with open or cracked shells. Freshly shucked mussels should smell perfectly fresh, with no trace of ammonia or a "fishy" smell. A simple criterion: pulling mussels or opening their shells kills them and they should be discarded.
Live mussels can be stored in the refrigerator, covered with wet kitchen towels or paper towels. Don't put them in an airtight container or submerge them in fresh water, or they will die. You can freeze shucked raw mussels in their liquid in airtight containers. They should keep for two months in the freezer. To prepare mussels for cooking (most commonly cooked without pulling mussels from their shells), scrub the shells and rinse under cold running water. Pull the stringy "beards"--the fibrous dark tufts protruding from the shells. When it comes to cooking mussels, the trick is to heat them sufficiently to destroy harmful organisms but not so long as to make the flesh too tough. This requires careful monitoring, as mussels can be toughened by just seconds of overcooking.