A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. Most seashells are made by mollusks, such as snails, clams, and oysters to protect their soft insides. Empty seashells are often found washed up on beaches by beachcombers. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another organism.
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.
Scallop is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families within the superfamily Pectinoidea, which also includes the thorny oysters.
Trigoniidae is a taxonomic family of saltwater clams, marine bivalve mollusks in the superfamily Trigonioidea. There is only one living genus, Neotrigonia, but in the geological past this family was well represented, widespread and common. The shells of species in this family are morphologically unusual, with very elaborate hinge teeth, and the exterior of the shell is highly ornamented.
Argopecten gibbus, the Atlantic calico scallop, is a species of medium-sized edible marine bivalve mollusk in the family Pectinidae, the scallops.
The Plicatulidae are a family of saltwater clams, marine bivalve mollusks, known commonly as kitten's paws or kittenpaws. These bivalves are related to oysters and scallops. The family has a single living genus, Plicatula, with a second, Harpax known from fossils.
Pecten jacobaeus, the Mediterranean scallop, is a species of scallop, an edible saltwater scallop, a marine bivalve mollusc in the family Pectinidae, the scallops.
A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk. In life, the shell of this class of mollusks is composed of two hinged parts or valves. Bivalves are very common in essentially all aquatic locales, including saltwater, brackish water, and freshwater. The shells of bivalves commonly wash up on beaches and along the edges of lakes, rivers, and streams. Bivalves by definition possess two shells or valves, a "right valve" and a "left valve", that are joined by a ligament. The two valves usually articulate with one another using structures known as "teeth" which are situated along the hinge line. In many bivalve shells, the two valves are symmetrical along the hinge line—when truly symmetrical, such an animal is said to be equivalved; if the valves vary from each other in size or shape, inequivalved. If symmetrical front-to-back, the valves are said to be equilateral, and are otherwise considered inequilateral.
Mimachlamys varia, also known under common names variegated scallop and black scallop, is a species of small scallop, a marine bivalve mollusk in the family Pectinidae, the scallops. It occurs in the North Sea, the English Channel, the eastern Atlantic Ocean, and the Mediterranean Sea.
Pecten maximus, common names the great scallop, king scallop, St James shell or escallop, is a northeast Atlantic species of scallop, an edible saltwater clam, a marine bivalve mollusc in the family Pectinidae. This is the type species of the genus. This species may be conspecific with Pecten jacobaeus, the pilgrim's scallop, which has a much more restricted distribution.
Euvola ziczac, or the zigzag scallop, is a species of bivalve mollusc in the family Pectinidae. It can be found along the Atlantic coast of North America, ranging from North Carolina to the West Indies and Bermuda.
Talochlamys multistriata, the dwarf fan shell, is a species of bivalve scallop. It is a marine mollusc in the family Pectinidae.
Chlamys hastata, the spear scallop, spiny scallop or swimming scallop, is a species of bivalve mollusc in the family Pectinidae found on the west coast of North America from the Gulf of Alaska to San Diego, California. A limited number of these scallops are harvested by divers or by narrow trawls off the west coast of Canada.
Annachlamys flabellata is a species of scallop, a marine bivalve mollusc in the family Pectinidae. It is found in the sublittoral zone of the continental shelf north of Australia.
The Antarctic scallop is a species of bivalve mollusc in the large family of scallops, the Pectinidae. It was thought to be the only species in the genus Adamussium until an extinct Pliocene species was described in 2016. Its exact relationship to other members of the Pectinidae is unclear. It is found in the ice-cold seas surrounding Antarctica, sometimes at great depths.
Crassadoma is a genus of rock scallops, marine bivalve molluscs in the family Pectinidae. It is monotypic, the only species being Crassadoma gigantea, the rock scallop, giant rock scallop or purple-hinge rock scallop. Although the small juveniles are free-swimming, they soon become sessile, and are cemented to the substrate. These scallops occur in the eastern Pacific Ocean.
A hinge ligament is a crucial part of the anatomical structure of a bivalve shell, i.e. the shell of a bivalve mollusk. The shell of a bivalve has two valves and these are joined by the ligament at the dorsal edge of the shell. The ligament is made of a strong, flexible and elastic, fibrous, proteinaceous material which is usually pale brown, dark brown or black in color.
The adductor muscles are the main muscular system in bivalve mollusks. In many parts of the world, when people eat scallops, the adductor muscles are the only part of the animal which is eaten. Adductor muscles leave noticeable scars or marks on the interior of the shell's valves. Those marks are often used by scientists who are in the process of identifying empty shells to determine their correct taxonomic placement.
Swiftopecten swifti, common name Swift's scallop, is a species of bivalve mollusc in the family Pectinidae. It occurs in the northern Pacific Ocean.
Mimachlamys is a genus of scallops, marine bivalve molluscs in the taxonomic family Pectinidae. There are at least 11 living species, including the glory scallop Mimachlamys gloriosa, and the Mimachlamys asperrima.
