Crassadoma | |
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A young rock scallop | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Bivalvia |
Order: | Pectinida |
Family: | Pectinidae |
Genus: | Crassadoma Bernard, 1986 [1] |
Species: | C. gigantea |
Binomial name | |
Crassadoma gigantea | |
Synonyms | |
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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.
Adults of Crassadoma gigantea have one valve (the right valve) fixed to a base, often a vertical rock face. This valve often becomes deformed to fit the contours of the rock. The left valve is roughly circular but irregular in outline, thick and heavy, with deep radial ribs. Every third or fourth rib is clad with blunt spines that overhang each other. These often get abraded and worn smooth as the scallop ages. There are flaps of shell known as auricles on either side of the straight hinge. The general colour is brown with the inside of the shell being glossy white with a purple patch at the hinge and a large, central adductor muscle scar. Crassadoma gigantea grows to a diameter of 15 centimetres (5.9 in) in the intertidal zone and 25 centimetres (9.8 in) in the subtidal zone. Between the valves, the margin of the orange mantle can be seen, with a row of tiny blue eyes and a sparse fringe of short tentacles. [3] [4]
Crassadoma gigantea is found on the Pacific Coast of North America, from British Columbia south to Baja California and Mexico. [3] It does not move around as an adult but lives on the sea floor. Its favoured habitats include inside crevices and under boulders, or cemented to rock surfaces, corals or man-made structures such as harbour pilings. [4] It is found at depths down to about 80 metres (260 ft). [5]
Like other scallops, Crassadoma gigantea is a filter feeder, filtering phytoplankton from water as it passes over the gills. The particles are moved by cilia along grooves to the mouth where edible matter is separated from sediment particles. The waste is incorporated into mucous balls which are removed from the mantle cavity periodically by a clapping of the valves. [6]
Crassadoma gigantea is cryptic and difficult to detect because of the sponges, sea anemones, hydroids, barnacles, bryozoans, worms and algae which tend to grow on the shell. The parasitic boring sponge Cliona celata damages the shell by making hollows in it. Additional shell material is laid down by the mantle tissue to compensate for this. Other sponges, such as the yellow boring sponge (Cliona californiana) [7] that grow on the shell may be considered mutualistic, granting some protection against predators such as the sunflower starfish (Pycnopodia helianthoides) and purple sea star (Pisaster ochraceus). [5] It has been found experimentally that rock scallops grow at a faster rate when living in deep rather than shallow water, perhaps because they are then less hindered by these fouling organisms. [6]
The sexes are separate in Crassadoma gigantea and spawning takes place in the summer. The veliger larvae that develop from the eggs form part of the zooplankton for about 40 days before settling, undergoing metamorphosis and beginning to form a shell. Juveniles are free living, are able to swim and can attach themselves temporarily to the substrate by byssus threads. By the time they have grown to 4.5 centimetres (1.8 in) in diameter they have usually cemented themselves to a hard surface and become sessile. Rock scallops can live for at least 20 years [4] but by about halfway through their adult life, growth slows, and energy is concentrated into gamete production. [8]
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.
Cliona californiana, the yellow boring sponge, boring sponge or sulphur sponge, is a species of demosponge belonging to the family Clionaidae. It is native to the north-eastern Pacific Ocean and burrows into the shell valves of bivalve molluscs.
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.
Chlamys varia, also called Mimachlamys varia common name the variegated 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 northeastern Atlantic Ocean and the Red Sea.
Flexopecten felipponei is a species of saltwater scallop, a marine bivalve mollusk in the family Pectinidae, the scallops.
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.
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.
Serpula vermicularis, known by common names including the calcareous tubeworm, fan worm, plume worm or red tube worm, is a species of segmented marine polychaete worm in the family Serpulidae. It is the type species of the genus Serpula and was first described by Carl Linnaeus in his 1767 12th edition of Systema Naturae. It lives in a tube into which it can retract.
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.
Enigmonia is a genus of saltwater clams, a marine bivalve mollusc in the family Anomiidae, the jingle shells. Enigmonia aenigmatica, the mangrove jingle shell clam, is the only species in this monotypic genus. It is found living on mangroves in the Indo-Pacific Ocean.
Venerupis corrugata, the pullet carpet shell, is a species of bivalve mollusc in the family Veneridae. It is found buried in the sediment on the sea bed in shallow parts of the eastern Atlantic Ocean. It is harvested for human consumption in Spain and other parts of Western Europe.
Chlamys rubida 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 prodissoconch is an embryonic or larval shell which is present in the larva of a bivalve mollusk. The prodissoconch is often but not always smooth, and has no growth lines. It is sometimes still present and visible in the adult shell, if there has been no erosion of the shell in that area.
Saxidomus gigantea is a large, edible saltwater clam, a marine bivalve mollusk in the family Veneridae, the venus clams. It can be found along the western coast of North America, ranging from the Aleutian Islands to San Francisco Bay. Common names for this clam include butter clam, Washington clam, smooth Washington clam and money shell.
Chlamys australis, common name the "austral scallop", is a species of scallop, a marine bivalve mollusc in the family Pectinidae, the scallops.
Chlamys swifti, common name Swift's scallop, is a species of bivalve mollusc in the family Pectinidae.
Pinctada margaritifera, commonly known as the black-lip pearl oyster, is a species of pearl oyster, a saltwater mollusk, a marine bivalve mollusk in the family Pteriidae. This species is common in the Indo-Pacific within tropical coral reefs.
Hinnites is a genus of rock scallops, marine bivalve mollusks in the family Pectinidae, the scallops.
Mycale adhaerens, the purple scallop sponge, is a species of marine demosponge in the family Mycalidae. Mycale is a large genus and this species is placed in the subgenus Aegogropila making its full name, Mycale (Aegogropila) adhaerens. It grows symbiotically on the valves of scallop shells and is native to the west coast of North America.