Once regarded as the poor relation of the shellfish family because of their small size mussels seafood boil relative abundance, mussels are now very popular and fairly cheap to buy. The most common blue or European mussels have sleek, shiny shells and tender, nutritious flesh. Like oysters, they are indiscriminate feeders and must be gathered from unpolluted waters. It’s because of this that most mussels sold in supermarkets and fishmongers are farmed.

Read more about responsible fishing at Seafish and Marine Stewardship Council. Peak season for fresh mussels is October to March. You can buy mussels in their shells year round. Fresh mussels tend to be tightly closed. Allow about 500g per person for a main meal, and half that amount for a starter or for use in pastas or soups. Discard any that float to the top. Place cleaned mussels in a fresh bowl of cold water until ready to use.

See our collection of mussels recipes. This website is published by Immediate Media Company Limited under licence from BBC Studios Distribution. On this Wikipedia the language links are at the top of the page across from the article title. In most marine mussels the shell is longer than it is wide, being wedge-shaped or asymmetrical. The external colour of the shell is often dark blue, blackish, or brown, while the interior is silvery and somewhat nacreous.

The common name “mussel” is also used for many freshwater bivalves, including the freshwater pearl mussels. Freshwater mussel species inhabit lakes, ponds, rivers, creeks, canals, and they are classified in a different subclass of bivalves, despite some very superficial similarities in appearance. Freshwater zebra mussels and their relatives in the family Dreissenidae are not related to previously mentioned groups, even though they resemble many Mytilus species in shape, and live attached to rocks and other hard surfaces in a similar manner, using a byssus. Marine blue mussel, Mytilus edulis, showing some of the inner anatomy.

The white posterior adductor muscle is visible in the upper image, and has been cut in the lower image to allow the valves to open fully. The mussel’s external shell is composed of two hinged halves or “valves”. Mussel shells carry out a variety of functions, including support for soft tissues, protection from predators and protection against desiccation. Like most bivalves, mussels have a large organ called a foot. In freshwater mussels, the foot is large, muscular, and generally hatchet-shaped. It does this by repeatedly advancing the foot through the substrate, expanding the end so it serves as an anchor, and then pulling the rest of the animal with its shell forward. In marine mussels, the foot is smaller, tongue-like in shape, with a groove on the ventral surface which is continuous with the byssus pit.

In this pit, a viscous secretion is exuded, entering the groove and hardening gradually upon contact with sea water. This forms extremely tough, strong, elastic, byssal threads that secure the mussel to its substrate allowing it to remain sessile in areas of high flow. In cooking, the byssus of the mussel is known as the “beard” and is removed during preparation, often after cooking when the mussel has opened. A mussel draws water in through its incurrent siphon.

Marine mussels are usually found clumping together on wave-washed rocks, each attached to the rock by its byssus. The clumping habit helps hold the mussels firm against the force of the waves. At low tide mussels in the middle of a clump will undergo less water loss because of water capture by the other mussels. Both marine and freshwater mussels are gonochoristic, with separate male and female individuals. In marine mussels, fertilization occurs outside the body, with a larval stage that drifts for three weeks to six months, before settling on a hard surface as a young mussel. There, it is capable of moving slowly by means of attaching and detaching byssal threads to attain a better life position.