Mussel is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.
Bivalvia, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. The class includes the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. Shipworms bore into wood, clay, or stone and live inside these substances.
A byssus is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells (Pinnidae), true mussels (Mytilidae), and Dreissenidae.
Dreissena is a genus of small freshwater mussels in the family Dreissenidae in the class Bivalvia. They are found attached to firm substrates by threads from underneath the shells and are the only freshwater bivalves to attach to hard substrates in high densities while having a planktonic larval stage. They are considered the most aggressive freshwater invader in the world because of their ability to invade environments in every one of their life cycle.
The Pinnidae are a taxonomic family of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order Pteriida.
Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves.
Perna perna, the brown mussel, is an economically important mussel, a bivalve mollusc belonging to the family Mytilidae. It is harvested as a food source but is also known to harbor toxins and cause damage to marine structures. It is native to the waters of Africa, Europe, and South America and was introduced in the waters of North America.
Pinna is a genus of bivalve molluscs belonging to the family Pinnidae.
Atrina is a cosmopolitan genus of bivalve molluscs belonging to the family Pinnidae.
Atrina rigida, commonly called the rigid pen shell, is a species of bivalve mollusc in the family Pinnidae.
Pinna nobilis, whose common name is the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells.
Modiolus modiolus, common name northern horsemussel, is a species of marine bivalve mollusk in the family Mytilidae.
Atrina squamifera, one of several species known as the horse mussel, is a species of bivalve pen shell. It is a marine mollusc in the family Pinnidae. It is endemic to South Africa.
Pinna carnea, commonly called the amber pen shell, is a species of bivalve mollusc in the family Pinnidae.
Atrina seminuda, the half-naked pen shell, is a species of bivalve mollusc in the family Pinnidae.
Atrina zelandica, one of several species known as the horse mussel, is a large species of saltwater clam in the family Pinnidae, the pen shells. This species is found around New Zealand.
Pinna rudis, the rough pen shell or spiny fan-mussel, is a species of bivalve mollusc in the family Pinnidae. It is the type species of the genus Pinna. Knowledge about this is sparse, with an absence of specific studies and literature.
Pinna bicolor, also known as razorfish, razor clam, or pen shell, is a species of large saltwater clam in the family Pinnidae. It is commonly found in shallow waters up to 50 m (160 ft) deep. It can be found embedded in firm muddy intertidal sediments, seagrass beds, and reef flats along continental and island shores.
South-West Deeps (West) MPA, along with the South West Deeps (East) MPA is an offshore Marine Conservation Zone (MCZ), approximately 230 km (140 mi) off Land's End, Cornwall, England, in the Western Channel and Celtic Sea. It was one of twenty-seven MCZs designated on 21 November 2013 by the Marine and Coastal Access Act 2009 and is a predominantly sandy area of the continental shelf, supporting molluscs and crustaceans living in and on the mixed and coarse sediments.
