What Are Mussels?

Most people are familiar with mussels because they are a common dish at seafood restaurants, especially those located near the coasts. They may not know much else about these underwater organisms besides what they taste like. This is unfortunate since the story of the mussel is actually quite interesting to learn.

  1. Classification

    • Mussels are members of the phylum mollusks, which means they consist of both a shell and a fleshy body inside the shell. They are also bivalves as their shells have two halves that are connected at the top. The mussel can hold its shell either open or closed. Closing the shell is a mussel's prime means of protecting itself.

    Appearance

    • Mussel shells, unlike some seashells, are not symmetrical. They tend to be oblong and get wider at the bottom. The shells are usually subdued in color. Common hues are black, gray, brown and blue. The mussel's body is quite soft and spongy and usually pale in appearance. This is the part that's important to the seafood lover.

    Habitat

    • Mussels can live in either saltwater or freshwater, depending on their species. They tend to make their homes in the shallow coastal areas of the ocean or near the edges of lakes or ponds. You'd be hard pressed to find a mussel in a muddy area. Their preference is for waterways with sand or rock basins.

    Daily Activities

    • Mussels anchor themselves to the rocks or sediment along the shore, usually in large groups. Once there, they are essentially sedentary. They are able to stay in one place with the help of their byssal threads, which are thin, silky fibers that can stick tightly to these surfaces. They typically exist as part of a large group, which helps them survive harsh waves and weather without being knocked loose. Mussels can store some water in their bodies but they cannot survive a low tide that leaves them uncovered long term.

    Diet

    • Mussels, like sponges and many other types of mollusks, are predominantly filter feeders. They siphon water into their branchial chambers using the cilia on their gills. Once the water is inside they can filter out any plankton or other small sea plants before excreting the excess water by way of an excurrent siphon.

    Reproduction

    • The mussel reproduction cycle is not much different from the feeding cycle. Male mussels secrete their sperm into the water surrounding them, hopefully in the direction of some female mussels. If a female senses that sperm is near, she will try to siphon it into her body. Once there, it can fertilize her eggs. In late spring females release their larvae into the water. Then they are on their own. Most do not survive to adulthood, which is why female mussels can produce several million eggs.