Mollusks Of The Deep Sea
According to a report on the journal Science, the unusual mollusks of oceanic cold sweeps – -strange clams, mussels, and sea snails – – that thrive on the sulfur and methane rich environments – – are on average older than marine mollusk rich community as a whole. Cold sweeps may have been safer harbors for the mollusks. It protects them from mass extinction. Due to the hydrogen sulfide and methane leak through the ocean floor, a unique chemical environment is created where the hardy bacteria process the sulfide and methane.
Clam, common name for many species of bivalve mollusks that burrow wholly or partly into sand or mud by means of a hatchet-shaped muscular foot. Clams are eaten throughout the world. Those commonly preferred for consumption in the are the round, or hard, clam and the long, or soft, clam.
The hard clam, which has a thick, heavy, vaguely heart-shaped shell, was named the quahog by the Native Americans. The quahog is native to coastal waters from the Gulf of Saint Lawrence to as far south as the Gulf of Mexico. Because this species does not burrow deeply, it may be obtained by raking the ocean bottom beyond the low-tide mark. Small and medium-sized quahogs are marketed as littlenecks and cherrystones, respectively, and they are usually eaten raw. Mature quahogs are used for chowder.
The soft-shell clam has a comparatively thin, elongated shell. It is found buried in the sand between tidemarks along the northern Atlantic coast from Labrador to as far south as North Carolina. When disturbed, it ejects a spurt of water and withdraws to safer depths in the sand. This clam-also called the steamer, or the steamer clam-is obtained by digging in the sand at low tide and is eaten steamed, fried, and in chowders.
Other edible clams in North America include the surf, or hen, clam, which is found from Nova Scotia to South Carolina, and the ocean quahog, found in deep waters from Newfoundland south to CapeHatteras. The Pacific razor clam abounds on the PacificCoast. The giant clam, found on the coral reefs of the Indian and Pacific oceans to great depths, is second in size only to the giant squid among the extant mollusks. It may weigh as much as 227 kg (500 lb), including the shell and it may yield about 9 kg (about 20 lb) of edible flesh.
Scientific classification: Clams belong to the class Bivalvia, phylum Mollusca. The hard clam is known as Mercenaria mercenaria, the soft-shell clam as Mya arenaria, the surf clam as Spisula solidissima, the ocean quahog as Arctica islandica, the Pacific razor clam as Siliqua patula, and the giant clam as Tridacna gigas.
Mussel, common name for any marine or freshwater bivalve mollusk closely related to oysters and scallops. Mussels are called filibranchiates, which means that the filaments, or branches, of their gills have interlocking bunches of hair like cilia.
The common sea mussel, found attached to rocks on the shores of Europe and , is widely used as food and fishing bait. Of the freshwater mussels, which are found in rivers and streams of North America, Europe, and Asia, about 60 commercially important species are found in the . Their shells are used in button making. The mussels themselves readily secrete pearls; most mussel pearls are of low quality and are used in making inexpensive jewelry. Studies of mussels show that they are severely affected by chemical pollutants. Some species, however, have become pests; since the mid-1980s the zebra mussel, native to the Caspian Sea, has invaded the Great Lakes and adjacent waterways in large numbers, threatening the region’s environment and economy.
Scientific classification: Mussels belong to the class Bivalvia, phylum Mollusca. The common sea mussel is classified as Mytilus edulis. The zebra mussel is known as Dreissena polymorpha.
Snail, any of as many as 50,000 marine, freshwater, and terrestrial species of mollusk. Gastropods (literally, belly-footed animals) have been able to adapt their singular means of locomotion to a wide range of water and land habitats, from the depths and shorelines of oceans to all bodies of fresh water, and from tropical areas to mountains and deserts.
Snails move by means of a wavelike series of muscular contractions along the bottom of the foot. This motion is often aided by cilia and, in land snails, by a track of laid-down slime. Snails feed mainly on algae and decaying matter and are important members of the food web, being a source of food to fish and waterfowl. A snail browses by means of a radula, a ribbon like tongue often containing many thousands of denticles, or teeth, which are projected from the mouth opening and drawn along rocks or leaves. Some carnivorous snails have radulae that bore holes through the shells of other mollusks to reach the soft flesh. Many species of snails are hermaphroditic and capable of self-fertilization.
Snails have prominent tentacles on which, in many species, the eyes are often located. Many snails are as small as 0.1 cm (0.04 in) long; others, such as conchs and the African land snail, are as long as 20 cm (8 in). The spiral shell into which the snail withdraws serves mainly as protection against predators and desiccation. Land snails are particularly well adapted to changes in moisture; some desert species are able to remain sealed within their thick shells for two or more years. Land snail species of more moist habitats usually have thinner shells; slugs, which live in very moist places and are often considered snails, have only vestigial shells.
Escargots, the snails of French cuisine, come from the cultivated land snail. Other edible snails are the abalone of California and , the periwinkle of Europe and , and the queen conch of the West Indies.
Scientific classification: Snails belong to the class Gastropoda. The African land snail is classified as Achatina fulica, and the cultivated land snail as Helix pomatia. Abalones are classified in the genus Haliotis and periwinkles in the genus Littorina. The queen conch is classified as Strombus gigas.
