Oyster farming is an aquaculture (or mariculture ) practice in which oysters are bred and raised mainly for their pearls , shells and inner organ tissue, which is eaten. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century.
105-448: Meretrix lusoria , the hamaguri , Asian hard clam or common Orient clam , is a species of saltwater clam, a marine bivalve mollusk in the family Veneridae , the Venus clams. This species is native to Asia, originally described around the waters of Japan . It is commercially exploited for sushi , and its shells are traditionally used to make white go stones. The hamaguri clam is
210-507: A stub . You can help Misplaced Pages by expanding it . Bivalve And see text Bivalvia ( / b aɪ ˈ v æ l v i ə / ) or bivalves , in previous centuries referred to as the Lamellibranchiata and Pelecypoda , is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half- shells known as valves . As
315-420: A different way, scraping detritus from the seabed, and this may be the original mode of feeding used by all bivalves before the gills became adapted for filter feeding. These primitive bivalves hold on to the bottom with a pair of tentacles at the edge of the mouth, each of which has a single palp , or flap. The tentacles are covered in mucus , which traps the food, and cilia, which transport the particles back to
420-528: A feature shared with two other major groups of marine invertebrates, the bryozoans and the phoronids . Some brachiopod shells are made of calcium phosphate but most are calcium carbonate in the form of the biomineral calcite , whereas bivalve shells are always composed entirely of calcium carbonate, often in the form of the biomineral aragonite . The Cambrian explosion took place around 540 to 520 million years ago (Mya). In this geologically brief period, most major animal phyla diverged including some of
525-403: A flexible ligament that, usually in conjunction with interlocking "teeth" on each of the valves, forms the hinge . This arrangement allows the shell to be opened and closed without the two halves detaching. The shell is typically bilaterally symmetrical , with the hinge lying in the sagittal plane . Adult shell sizes of bivalves vary from fractions of a millimetre to over a metre in length, but
630-408: A group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore . Their gills have evolved into ctenidia , specialised organs for feeding and breathing. Common bivalves include clams , oysters , cockles , mussels , scallops , and numerous other families that live in saltwater, as well as a number of families that live in freshwater. Majority of
735-460: A hinged shell in two parts. However, brachiopods evolved from a very different ancestral line, and the resemblance to bivalves only arose because they occupy similar ecological niches . The differences between the two groups are due to their separate ancestral origins. Different initial structures have been adapted to solve the same problems, a case of convergent evolution . In modern times, brachiopods are not as common as bivalves. Both groups have
840-586: A hole with its radula assisted by a shell-dissolving secretion. The dog whelk then inserts its extendible proboscis and sucks out the body contents of the victim, which is typically a blue mussel . Oyster farming Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula. With the Barbarian invasions the oyster farming in the Mediterranean and
945-455: A method to combat climate change, because the growth of the oyster shell sequesters atmospheric carbon dioxide in a form (calcium carbonate) that is stable over geologic time. In The United States, the cultivation of Pacific oysters in tidal areas not only improves water quality in the ocean but oyster cultivation also works to improve government policy. Oyster farming must obey federal regulations, maps, and models. Federal regulation monitors
1050-499: A pair of nephridia . Each of these consists of a long, looped, glandular tube, which opens into the pericardium , and a bladder to store urine. They also have pericardial glands either line the auricles of the heart or attach to the pericardium, and serve as extra filtration organs. Metabolic waste is voided from the bladders through a nephridiopore near the front of the upper part of the mantle cavity and excreted. The sexes are usually separate in bivalves but some hermaphroditism
1155-484: A relatively small dispersal potential before settling out. The common mussel ( Mytilus edulis ) produces 10 times as many eggs that hatch into larvae and soon need to feed to survive and grow. They can disperse more widely as they remain planktonic for a much longer time. Freshwater bivalves have different lifecycle. Sperm is drawn into a female's gills with the inhalant water and internal fertilization takes place. The eggs hatch into glochidia larvae that develop within
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#17327648188151260-644: A resting state, even when they are permanently submerged. In oysters, for example, their behaviour follows very strict circatidal and circadian rhythms according to the relative positions of the moon and sun. During neap tides, they exhibit much longer closing periods than during spring tides. Although many non-sessile bivalves use their muscular foot to move around, or to dig, members of the freshwater family Sphaeriidae are exceptional in that these small clams climb about quite nimbly on weeds using their long and flexible foot. The European fingernail clam ( Sphaerium corneum ), for example, climbs around on water weeds at
1365-424: A shadow falling over the animal. Bivalves have an open circulatory system that bathes the organs in blood ( hemolymph ). The heart has three chambers: two auricles receiving blood from the gills, and a single ventricle . The ventricle is muscular and pumps hemolymph into the aorta , and then to the rest of the body. Some bivalves have a single aorta, but most also have a second, usually smaller, aorta serving
1470-436: A shell consisting of two valves, but the organization of the shell is quite different in the two groups. In brachiopods, the two valves are positioned on the dorsal and ventral surfaces of the body, while in bivalves, the valves are on the left and right sides of the body, and are, in most cases, mirror images of one other. Brachiopods have a lophophore , a coiled, rigid cartilaginous internal apparatus adapted for filter feeding,
1575-417: A short window. All of the oysters in an area will spawn at the same time to increase the chances that their gametes meet and fertile larvae are produced. To ensure ripe oysters for spawning throughout the season, some growers choose to keep mature oysters in a separate system where the farmer can manipulate the temperature and food within the system. While a recirculating system can be used, a flow-through system
1680-424: A steady pull. Paired pedal protractor and retractor muscles operate the animal's foot. The sedentary habits of the bivalves have meant that in general the nervous system is less complex than in most other molluscs. The animals have no brain ; the nervous system consists of a nerve network and a series of paired ganglia . In all but the most primitive bivalves, two cerebropleural ganglia are on either side of
1785-481: A tray and rapidly heat and cool the water to induce spawning. It is important to have a large number of oysters, because it is impossible to tell if an oyster is male or female from its outer appearance. Once the oysters start to spawn they can be picked up and placed into their own separate containers until they have released all of their gametes. Eggs and sperm can then be mixed together to fertilize. Larvae tanks should be cleaned and disinfected before putting water in
1890-428: Is a disease that is carried by oysters and other shellfish and can make people sick, but is not harmful to the oyster itself. Vibrio can only be passed from oysters to humans if they are consumed raw. Vibrio is more common in warmer waters, and all commercial shellfish must be refrigerated before being served in an attempt to kill the vibrio bacterium. Polydorid polychaetes are known as pests of cultured oysters. In
1995-520: Is being considered. Recreational oyster harvesting is strictly prohibited to protect both the threatened oysters and to protect people from potential disease. Bycatch reduction devices are required and violation results in a small fine. Supporters of Delaware's legislation to allow aquaculture cite: revenue, job creation, and nutrient cycling as the benefits. For example, It is estimated that one acre can produce nearly 750,000 oysters, which could filter between 15 and 40 million gallons of water daily. This
2100-432: Is composed of two calcareous valves held together by a ligament. The valves are made of either calcite , as is the case in oysters, or both calcite and aragonite . Sometimes, the aragonite forms an inner, nacreous layer, as is the case in the order Pteriida . In other taxa , alternate layers of calcite and aragonite are laid down. The ligament and byssus, if calcified, are composed of aragonite. The outermost layer of
2205-417: Is encouraged for the ecosystem services they provide, including water quality maintenance, shoreline protection and sediment stabilization, nutrient cycling and sequestration, and habitat for other organisms. There has been a decline in oyster population due to extensive factors such as climate change and overharvesting of wild populations. Because of this, oyster reef restoration has been significant in
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#17327648188152310-477: Is extremely beneficial to the marine ecosystem because the oysters feed on particulate matter and nitrogen, often from anthropogenic sources. This, in turn, reduces the algae growth and leads to an overall cleaner marine environment. Other sources state that a single oyster can filter 24–96 liters a day (1–4 liters per hour). With 750,000 oysters in one acre, 18,000,000-72,000,000 liters of water can be filtered, removing most forms of particulate matter suspended in
2415-419: Is generally better because the natural diversity of phytoplankton is a better diet for conditioning oysters. By setting up this separate system, the farmer can mimic the transition from winter to summer quicker than real-time, and essentially convince the oyster that it is time to spawn whenever the farmer needs more larvae. When the farmer actually wants to spawn the oysters, they will put a batch of oysters in
2520-557: Is known. The gonads either open into the nephridia or through a separate pore into a chamber over the gills. The ripe gonads of males and females release sperm and eggs into the water column . Spawning may take place continually or be triggered by environmental factors such as day length, water temperature, or the presence of sperm in the water. Some species are "dribble spawners", releasing gametes during protracted period that can extend for weeks. Others are mass spawners and release their gametes in batches or all at once. Fertilization
2625-460: Is lethal to C. virginica . It is a single-celled protozoan with an unknown method of transmission between oysters. It does not appear to transfer from oyster-to-oyster like Dermo does. After an outbreak in 1997, a strain of MSX-resistant oysters were developed. MSX can be suppressed by low temperatures and low salinities, but once infected, oysters will die within a month. MSX and Dermo are both considered to be non-harmful to humans. Vibrio, however,
2730-453: Is possible to distinguish several species: There is one report in 2022 of M. lusoria appearing in Sarawak ( Malaysian Borneo ). The identification was confirmed by mtDNA phylogeny matching to Japanese M. lusoria . Interestingly, what appeared morphologically to be M. meretrix and M. lyrata at the same site gave very similar mtDNA results. This Veneridae -related article is
2835-408: Is secreted by the mantle edge, and the valves themselves thicken as more material is secreted from the general mantle surface. Calcareous matter comes from both its diet and the surrounding seawater. Concentric rings on the exterior of a valve are commonly used to age bivalves. For some groups, a more precise method for determining the age of a shell is by cutting a cross section through it and examining
2940-472: Is the ventral or underside region. The anterior or front of the shell is where the byssus (when present) and foot are located, and the posterior of the shell is where the siphons are located. With the hinge uppermost and with the anterior edge of the animal towards the viewer's left, the valve facing the viewer is the left valve and the opposing valve the right. Many bivalves such as clams, which appear upright, are evolutionarily lying on their side. The shell
3045-432: Is usually external. Typically, a short stage lasts a few hours or days before the eggs hatch into trochophore larvae. These later develop into veliger larvae which settle on the seabed and undergo metamorphosis into adults. In some species, such as those in the genus Lasaea , females draw water containing sperm in through their inhalant siphons and fertilization takes place inside the female. These species then brood
3150-629: Is usually full or ground up oyster shell because oysters are naturally attracted to other oyster shell to ensure their future reproductive success. After the larvae settle, they are considered "spat." Three methods of cultivation are commonly used. In each case oysters are cultivated to the size of "spat," the point at which they attach themselves to a substrate. The substrate is known as a " cultch " (also spelled "cutch" or "culch"). The loose spat may be allowed to mature further to form "seed" oysters with small shells. In either case (spat or seed stage), they are then set out to mature. The maturation technique
3255-411: Is where the cultivation method choice is made. In one method the spat or seed oysters are distributed over existing oyster beds and left to mature naturally. Such oysters will then be collected using the methods for fishing wild oysters , such as dredging . In the second method the spat or seed may be put in racks, bags, or cages (or they may be glued in threes to vertical ropes) which are held above
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3360-459: The C. gigas species of oyster. Pathogens of O. edulis oysters include Marteilia refringens and Bonamia ostreae . Dermo disease is caused by a protozoan parasite that infects the oyster's blood cells: Perkinsus marinus . It is spread when infective stages are released into the water column from an infected oyster and siphoned into a new host. It is most common in water above 77 °F. MSX stands for “Multinucleated Sphere Unknown” and
3465-558: The Chesapeake Bay . The Chesapeake Bay Foundation started working in conjunction with the Smithsonian Institution in 2022 to revive the oyster population that was disrupted due to the poor health of the water quality. In the U.S., Delaware is the only East Coast state without oyster aquaculture, but making aquaculture a state-controlled industry of leasing water by the acre for commercial harvesting of shellfish
3570-612: The Early Silurian , the gills were becoming adapted for filter feeding, and during the Devonian and Carboniferous periods, siphons first appeared, which, with the newly developed muscular foot, allowed the animals to bury themselves deep in the sediment. By the middle of the Paleozoic , around 400 Mya, the brachiopods were among the most abundant filter feeders in the ocean, and over 12,000 fossil species are recognized. By
3675-726: The Permian–Triassic extinction event 250 Mya, bivalves were undergoing a huge radiation of diversity. The bivalves were hard hit by this event, but re-established themselves and thrived during the Triassic period that followed. In contrast, the brachiopods lost 95% of their species diversity . The ability of some bivalves to burrow and thus avoid predators may have been a major factor in their success. Other new adaptations within various families allowed species to occupy previously unused evolutionary niches. These included increasing relative buoyancy in soft sediments by developing spines on
3780-587: The Veneridae , with more than 680 species and the Tellinidae and Lucinidae , each with over 500 species. The freshwater bivalves include seven families, the largest of which are the Unionidae , with about 700 species. The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves . More recently,
3885-408: The fossil record first in the early Cambrian more than 500 million years ago. The total number of known living species is about 9,200. These species are placed within 1,260 genera and 106 families. Marine bivalves (including brackish water and estuarine species) represent about 8,000 species, combined in four subclasses and 99 families with 1,100 genera. The largest recent marine families are
3990-597: The intertidal and sublittoral zones of the oceans. A sandy sea beach may superficially appear to be devoid of life, but often a very large number of bivalves and other invertebrates are living beneath the surface of the sand. On a large beach in South Wales , careful sampling produced an estimate of 1.44 million cockles ( Cerastoderma edule ) per acre of beach. Bivalves inhabit the tropics, as well as temperate and boreal waters. A number of species can survive and even flourish in extreme conditions. They are abundant in
4095-517: The oesophagus . The cerebral ganglia control the sensory organs, while the pleural ganglia supply nerves to the mantle cavity. The pedal ganglia, which control the foot, are at its base, and the visceral ganglia, which can be quite large in swimming bivalves, are under the posterior adductor muscle. These ganglia are both connected to the cerebropleural ganglia by nerve fibres . Bivalves with long siphons may also have siphonal ganglia to control them. The sensory organs of bivalves are largely located on
4200-400: The " crystalline style " projected into the stomach from an associated sac. Cilia in the sac cause the style to rotate, winding in a stream of food-containing mucus from the mouth, and churning the stomach contents. This constant motion propels food particles into a sorting region at the rear of the stomach, which distributes smaller particles into the digestive glands, and heavier particles into
4305-465: The 1880s, a powerboat called the Chesapeake Bay deadrise was also developed. Since 1977, several boat builders in Brittany have built specialized amphibious vehicles for use in the area's mussel and oyster farming industries. The boats are made of aluminium, are relatively flat-bottomed, and have three, four, or six wheels, depending on the size of the boat. When the tide is out the boats can run on
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4410-544: The 1st Century to approximately the 4th Century. They would export the oysters back to Rome and throughout the Roman Empire. On July 25, 1864, The Herne Bay Hampton and Recuiver Oyster Fishery Company moved into the area to start oyster farming. In the 1870s the oyster trade suffered from overfishing and sent the industry into a decline. This caused the government of the United Kingdom to pass the 1877 Act to solve
4515-458: The Arctic, about 140 species being known from that zone. The Antarctic scallop, Adamussium colbecki , lives under the sea ice at the other end of the globe, where the subzero temperatures mean that growth rates are very slow. The giant mussel, Bathymodiolus thermophilus , and the giant white clam, Calyptogena magnifica , both live clustered around hydrothermal vents at abyssal depths in
4620-543: The Atlantic came to an end. In fact, the Romans were the very first to cultivate Oysters. The Roman engineer Sergius Orata is known for his innovative ways of breeding and commercializing oysters. He did this by cultivating the mollusk with a system that could control the water levels. In 1852 Monsieur de Bon started to re-seed the oyster beds by collecting the oyster spawn using makeshift catchers. An important step to
4725-464: The Pacific Ocean. They have chemosymbiotic bacteria in their gills that oxidise hydrogen sulphide , and the molluscs absorb nutrients synthesized by these bacteria. Some species are found in the hadal zone , like Vesicomya sergeevi, which occurs at depths of 7600–9530 meters. The saddle oyster, Enigmonia aenigmatica , is a marine species that could be considered amphibious . It lives above
4830-676: The Romans started. The oysters would get shipped to Italy, where Roman Emperors would pay for them by their weight in gold. Commonly farmed food oysters include the Eastern oyster Crassostrea virginica , the Pacific oyster Crassostrea gigas , Belon oyster Ostrea edulis , the Sydney rock oyster Saccostrea glomerata , and the Southern mud oyster Ostrea angasi . Oysters naturally grow in estuarine bodies of brackish water . When farmed,
4935-418: The air, can gape the shell slightly and gas exchange can take place. Oysters, including the Pacific oyster ( Magallana gigas ), are recognized as having varying metabolic responses to environmental stress, with changes in respiration rate being frequently observed. Most bivalves are filter feeders , using their gills to capture particulate food such as phytoplankton from the water. Protobranchs feed in
5040-476: The bottom. Oysters cultivated in this manner may be harvested by lifting the bags or racks to the surface and removing mature oysters, or simply retrieving the larger oysters when the enclosure is exposed at low tide. The latter method may avoid losses to some predators, but is more expensive. In the third method the spat or seed are placed in a cultch within an artificial maturation tank. The maturation tank may be fed with water that has been especially prepared for
5145-588: The class are benthic filter feeders that 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 scallops and file shells , can swim . Shipworms bore into wood, clay, or stone and live inside these substances. The shell of a bivalve is composed of calcium carbonate , and consists of two, usually similar, parts called valves . These valves are for feeding and for disposal of waste. These are joined together along one edge (the hinge line ) by
5250-572: The class was known as Pelecypoda, meaning " axe -foot" (based on the shape of the foot of the animal when extended). The name "bivalve" is derived from the Latin bis , meaning 'two', and valvae , meaning 'leaves of a door'. ("Leaf" is an older word for the main, movable part of a door. We normally consider this the door itself.) Paired shells have evolved independently several times among animals that are not bivalves; other animals with paired valves include certain gastropods (small sea snails in
5355-422: The earth environment as they generate a significant amount of greenhouse gases. Oysters, however, produce little to no greenhouse gases, and the difference in emissions between wild oysters and farmed oysters is negligible. The oysters themselves do not produce any methane, one of the most potent greenhouse gases, and just a very minimal amount of nitrous oxide and carbon dioxide. Restoration of oyster populations
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#17327648188155460-436: The edges of lakes and ponds; this enables the clam to find the best position for filter feeding. The thick shell and rounded shape of bivalves make them awkward for potential predators to tackle. Nevertheless, a number of different creatures include them in their diet. Many species of demersal fish feed on them including the common carp ( Cyprinus carpio ), which is being used in the upper Mississippi River to try to control
5565-402: The family Juliidae ), members of the phylum Brachiopoda and the minute crustaceans known as ostracods and conchostracans . Bivalves have bilaterally symmetrical and laterally flattened bodies, with a blade-shaped foot, vestigial head and no radula . At the dorsal or back region of the shell is the hinge point or line, which contain the umbo and beak and the lower, curved margin
5670-421: The female's shell. Later they are released and attach themselves parasitically to the gills or fins of a fish host. After several weeks they drop off their host, undergo metamorphosis and develop into adults on the substrate . Some of the species in the freshwater mussel family, Unionidae , commonly known as pocketbook mussels, have evolved an unusual reproductive strategy. The female's mantle protrudes from
5775-434: The first creatures with mineralized skeletons. Brachiopods and bivalves made their appearance at this time, and left their fossilized remains behind in the rocks. Possible early bivalves include Pojetaia and Fordilla ; these probably lie in the stem rather than crown group. Watsonella and Anabarella are perceived to be (earlier) close relatives of these taxa. Only five genera of supposed Cambrian "bivalves" exist,
5880-434: The fish's gills, where they attach and trigger a tissue response that forms a small cyst around each larva. The larvae then feed by breaking down and digesting the tissue of the fish within the cysts. After a few weeks they release themselves from the cysts and fall to the stream bed as juvenile molluscs. Brachiopods are shelled marine organisms that superficially resemble bivalves in that they are of similar size and have
5985-467: The gills are also much longer than those in more primitive bivalves, and are folded over to create a groove through which food can be transported. The structure of the gills varies considerably, and can serve as a useful means for classifying bivalves into groups. A few bivalves, such as the granular poromya ( Poromya granulata ), are carnivorous , eating much larger prey than the tiny microalgae consumed by other bivalves. Muscles draw water in through
6090-595: The high tide mark in the tropical Indo-Pacific on the underside of mangrove leaves, on mangrove branches, and on sea walls in the splash zone . Some freshwater bivalves have very restricted ranges. For example, the Ouachita creekshell mussel, Villosa arkansasensis , is known only from the streams of the Ouachita Mountains in Arkansas and Oklahoma, and like several other freshwater mussel species from
6195-434: The hind parts of the animal. The hemolymph usually lacks any respiratory pigment. In the carnivorous genus Poromya , the hemolymph has red amoebocytes containing a haemoglobin pigment. The paired gills are located posteriorly and consist of hollow tube-like filaments with thin walls for gas exchange . The respiratory demands of bivalves are low, due to their relative inactivity. Some freshwater species, when exposed to
6300-399: The incremental growth bands. The shipworms , in the family Teredinidae have greatly elongated bodies, but their shell valves are much reduced and restricted to the anterior end of the body, where they function as scraping organs that permit the animal to dig tunnels through wood. The main muscular system in bivalves is the posterior and anterior adductor muscles. These muscles connect
6405-526: The inhalant siphon is surrounded by vibration-sensitive tentacles for detecting prey. Many bivalves have no eyes, but a few members of the Arcoidea, Limopsoidea, Mytiloidea, Anomioidea, Ostreoidea, and Limoidea have simple eyes on the margin of the mantle. These consist of a pit of photosensory cells and a lens . Scallops have more complex eyes with a lens, a two-layered retina , and a concave mirror. All bivalves have light-sensitive cells that can detect
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#17327648188156510-421: The inhalant siphon which is modified into a cowl-shaped organ, sucking in prey. The siphon can be retracted quickly and inverted, bringing the prey within reach of the mouth. The gut is modified so that large food particles can be digested. The unusual genus, Entovalva , is endosymbiotic , being found only in the oesophagus of sea cucumbers . It has mantle folds that completely surround its small valves. When
6615-443: The intestine. Waste material is consolidated in the rectum and voided as pellets into the exhalent water stream through an anal pore. Feeding and digestion are synchronized with diurnal and tidal cycles. Carnivorous bivalves generally have reduced crystalline styles and the stomach has thick, muscular walls, extensive cuticular linings and diminished sorting areas and gastric chamber sections. The excretory organs of bivalves are
6720-494: The invasive zebra mussel ( Dreissena polymorpha ). Birds such as the Eurasian oystercatcher ( Haematopus ostralegus ) have specially adapted beaks which can pry open their shells. The herring gull ( Larus argentatus ) sometimes drops heavy shells onto rocks in order to crack them open. Sea otters feed on a variety of bivalve species and have been observed to use stones balanced on their chests as anvils on which to crack open
6825-485: The largest living bivalve is the giant clam Tridacna gigas , which can grow to a length of 1,200 mm (47 in) and a weight of more than 200 kg (441 lb). The largest known extinct bivalve is a species of Platyceramus whose fossils measure up to 3,000 mm (118 in) in length. In his 2010 treatise, Compendium of Bivalves , Markus Huber gives the total number of living bivalve species as about 9,200 combined in 106 families. Huber states that
6930-443: The larvae, and their water quality stays pristine to encourage growth. This is the most fragile stage of an oyster's life history. After about two weeks an oyster will be ready to set. They will develop a small, round discoloration called an eyespot despite not being used for seeing. Their muscular foot will be visible under a microscope. At this point, the larvae can be put in a system with a variety of cultch options. The best cultch
7035-484: The least susceptible to predators and poaching, but is the most expensive to build and to operate. The Pacific oyster M. gigas is the species most commonly used with this type of farming. During the nineteenth century in the United States, various shallow draft sailboat designs were developed for oystering in Chesapeake Bay . These included the bugeye , log canoe , pungy , sharpie and skipjack . During
7140-780: The location and construction of the Claude Lewis Carlsbad Desalination Plant through the federal Clean Water Act on April 7, 2016, whose main focus was minimizing environmental impact in conjunction with Carlsbad Aquafarm. Applications and permits for aquaculture projects such as the Avalon Ocean Farm are made public and required to follow the same guidelines of the EPA and the CWA . Water Quality, Marine Mammals (including endangered species ), and forecasted environmental impact evaluations are listed in
7245-429: The majority of species do not exceed 10 cm (4 in). Bivalves have long been a part of the diet of coastal and riparian human populations. Oysters were cultured in ponds by the Romans, and mariculture has more recently become an important source of bivalves for food. Modern knowledge of molluscan reproductive cycles has led to the development of hatcheries and new culture techniques. A better understanding of
7350-418: The mantle lobes secrete the valves, and the mantle crest secretes the whole hinge mechanism consisting of ligament , byssus threads (where present), and teeth . The posterior mantle edge may have two elongated extensions known as siphons , through one of which water is inhaled, and the other expelled. The siphons retract into a cavity, known as the pallial sinus . The shell grows larger when more material
7455-452: The mantle though the valves. In sedentary or recumbent bivalves that lie on one valve, such as the oysters and scallops, the anterior adductor muscle has been lost and the posterior muscle is positioned centrally. In species that can swim by flapping their valves, a single, central adductor muscle occurs. These muscles are composed of two types of muscle fibres, striated muscle bundles for fast actions and smooth muscle bundles for maintaining
7560-678: The modern oyster farming was the oyster farm built by Hyacinthe Boeuf in the Ile de Ré . After obtaining the rights to a part of the coast he built a wall to make a reservoir and to break the strength of the current. Some time later the wall was covered with spat coming spontaneously from the sea which gave 2000 baby oysters per square metre. The Ancient Romans started farming the Thames Estuary in Hampton-On-Sea, or Kent, England from
7665-422: The number of 20,000 living species, often encountered in literature, could not be verified and presents the following table to illustrate the known diversity: The bivalves are a highly successful class of invertebrates found in aquatic habitats throughout the world. Most are infaunal and live buried in sediment on the seabed, or in the sediment in freshwater habitats. A large number of bivalve species are found in
7770-507: The others being Tuarangia , Camya and Arhouriella and potentially Buluniella . Bivalve fossils can be formed when the sediment in which the shells are buried hardens into rock. Often, the impression made by the valves remains as the fossil rather than the valves. During the Early Ordovician , a great increase in the diversity of bivalve species occurred, and the dysodont, heterodont, and taxodont dentitions evolved. By
7875-400: The palps. These then sort the particles, rejecting those that are unsuitable or too large to digest, and conveying others to the mouth. In more advanced bivalves, water is drawn into the shell from the posterior ventral surface of the animal, passes upwards through the gills, and doubles back to be expelled just above the intake. There may be two elongated, retractable siphons reaching up to
7980-585: The past decades, and a native Olympia oyster restoration project has been implemented in Liberty Bay , Washington. This project uses a "Habitat Sustainability Index (HSI)" to assess the ecological impacts of the restoration. The HSI also measures the benefit to the oyster population as well. Oyster farming in the Chesapeake Bay has minimal or even positive impacts on the surrounding environment, and numerous oyster restoration projects are underway in
8085-523: The period is before the larva first feeds, the larger the egg and yolk need to be. The reproductive cost of producing these energy-rich eggs is high and they are usually smaller in number. For example, the Baltic tellin ( Macoma balthica ) produces few, high-energy eggs. The larvae hatching out of these rely on the energy reserves and do not feed. After about four days, they become D-stage larvae, when they first develop hinged, D-shaped valves. These larvae have
8190-409: The posterior mantle margins. The organs are usually mechanoreceptors or chemoreceptors , in some cases located on short tentacles . The osphradium is a patch of sensory cells located below the posterior adductor muscle that may serve to taste the water or measure its turbidity . Statocysts within the organism help the bivalve to sense and correct its orientation. In the order Anomalodesmata ,
8295-425: The potential hazards of eating raw or undercooked shellfish has led to improved storage and processing. Pearl oysters (the common name of two very different families in salt water and fresh water) are the most common source of natural pearls . The shells of bivalves are used in craftwork, and the manufacture of jewellery and buttons. Bivalves have also been used in the biocontrol of pollution. Bivalves appear in
8400-501: The problem. This act prevented the sale of dredged oysters from the months of June through August, and freshwater pond oyster sales from between May and August. A couple of years later the company closed its doors and all the assets were sold by 1881, closing the oyster farming in the Thames Estuary area in England. Another place in England that is famous for its oyster fishing is Whistable. The area's “kentish flats” have been used since
8505-485: The project's description to minimize, manage, and mitigate its environmental impact. Oyster predators include starfish , oyster drill snails , stingrays , Florida stone crabs , birds, such as oystercatchers and gulls , and humans . Pathogens that can affect either farmed C. virginica or C. gigas oysters include Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX). However, C. virginica are much more susceptible to Dermo or MSX infections than are
8610-527: The prominence of modern bivalves over brachiopods seems due to chance disparities in their response to extinction events . The adult maximum size of living species of bivalve ranges from 0.52 mm (0.02 in) in Condylonucula maya , a nut clam, to a length of 1,532 millimetres (60.3 in) in Kuphus polythalamia , an elongated, burrowing shipworm. However, the species generally regarded as
8715-399: The purpose of accelerating the growth rate of the oysters. In particular the temperature and salinity of the water may be altered somewhat from nearby ocean water. The carbonate minerals calcite and aragonite in the water may help oysters develop their shells faster and may also be included in the water processing prior to introduction to the tanks. This latter cultivation technique may be
8820-530: The safety of the environment and the health effects on humans. For example, Carlsbad Aquafarm located in Southern California is cultivating Pacific oysters by using rafts and trays to utilize space to optimize production while operating near the newly opened Claude Lewis Carlsbad Desalination Plant . New adopted environmental impact regulations and policies were created and updated by The United States Environmental Protection Agency , which approved
8925-496: The sea cucumber sucks in sediment, the bivalve allows the water to pass over its gills and extracts fine organic particles. To prevent itself from being swept away, it attaches itself with byssal threads to the host 's throat. The sea cucumber is unharmed. The digestive tract of typical bivalves consists of an oesophagus , stomach , and intestine . Protobranch stomachs have a mere sac attached to them while filter-feeding bivalves have elongated rod of solidified mucus referred to as
9030-419: The seabed, one each for the inhalant and exhalant streams of water. The gills of filter-feeding bivalves are known as ctenidia and have become highly modified to increase their ability to capture food. For example, the cilia on the gills, which originally served to remove unwanted sediment, have become adapted to capture food particles, and transport them in a steady stream of mucus to the mouth. The filaments of
9135-427: The sediment at the bottom of waterways. To remove these contaminants from the sediment, species of seaweed can also be added to the aquaculture to take up some of these contaminants in their plant tissues. The seaweed can then be removed and taken to a contained area where the contamination is benign to the surrounding environment. More recently, large-scale cultivation of oysters and other shellfish has been proposed as
9240-469: The sediment remains damp even when the tide is out. When buried in the sediment, burrowing bivalves are protected from the pounding of waves, desiccation, and overheating during low tide, and variations in salinity caused by rainwater. They are also out of the reach of many predators. Their general strategy is to extend their siphons to the surface for feeding and respiration during high tide, but to descend to greater depths or keep their shell tightly shut when
9345-435: The shell and develops into an imitation small fish, complete with fish-like markings and false eyes. This decoy moves in the current and attracts the attention of real fish. Some fish see the decoy as prey, while others see a conspecific . They approach for a closer look and the mussel releases huge numbers of larvae from its gills, dousing the inquisitive fish with its tiny, parasitic young. These glochidia larvae are drawn into
9450-468: The shell is the periostracum , a thin layer composed of horny conchiolin . The periostracum is secreted by the outer mantle and is easily abraded. The outer surface of the valves is often sculpted, with clams often having concentric striations, scallops having radial ribs and oysters a latticework of irregular markings. In all molluscs, the mantle forms a thin membrane that covers the animal's body and extends out from it in flaps or lobes. In bivalves,
9555-571: The shell, gaining the ability to swim, and in a few cases, adopting predatory habits. For a long time, bivalves were thought to be better adapted to aquatic life than brachiopods were, outcompeting and relegating them to minor niches in later ages. These two taxa appeared in textbooks as an example of replacement by competition. Evidence given for this included the fact that bivalves needed less food to subsist because of their energetically efficient ligament-muscle system for opening and closing valves. All this has been broadly disproven, though; rather,
9660-420: The shells and open them more easily when they could tackle them from different angles. Octopuses either pull bivalves apart by force, or they bore a hole into the shell and insert a digestive fluid before sucking out the liquified contents. Certain carnivorous gastropod snails such as whelks ( Buccinidae ) and murex snails ( Muricidae ) feed on bivalves by boring into their shells. A dog whelk ( Nucella ) drills
9765-400: The shells with their pincers and starfish use their water vascular system to force the valves apart and then insert part of their stomach between the valves to digest the bivalve's body. It has been found experimentally that both crabs and starfish preferred molluscs that are attached by byssus threads to ones that are cemented to the substrate. This was probably because they could manipulate
9870-740: The shells. The Pacific walrus ( Odobenus rosmarus divergens ) is one of the main predators feeding on bivalves in Arctic waters. Shellfish have formed part of the human diet since prehistoric times, a fact evidenced by the remains of mollusc shells found in ancient middens. Examinations of these deposits in Peru has provided a means of dating long past El Niño events because of the disruption these caused to bivalve shell growth. Further changes in shell development due to environmental stress has also been suggested to cause increased mortality in oysters due to reduced shell strength. Invertebrate predators include crustaceans, starfish and octopuses. Crustaceans crack
9975-584: The southeastern US, it is in danger of extinction. In contrast, a few species of freshwater bivalves, including the golden mussel ( Limnoperna fortunei ), are dramatically increasing their ranges. The golden mussel has spread from Southeast Asia to Argentina, where it has become an invasive species . Another well-travelled freshwater bivalve, the zebra mussel ( Dreissena polymorpha ) originated in southeastern Russia, and has been accidentally introduced to inland waterways in North America and Europe, where
10080-416: The species damages water installations and disrupts local ecosystems . Most bivalves adopt a sedentary or even sessile lifestyle, often spending their whole lives in the area in which they first settled as juveniles. The majority of bivalves are infaunal, living under the seabed, buried in soft substrates such as sand, silt, mud, gravel, or coral fragments. Many of these live in the intertidal zone where
10185-473: The subject of a haiku by Matsuo Bashō . Meretrix lusoria is morphologically similar to a number of closely related species, making identification and reports of distribution quite confusing. Less precise sources may describe a large range in East Asia, in waters tropic to temperate. However, as Hsiao & Chuang (2023) demonstrated using molecular (nuclear + mtDNA) and multi-variate morphological means, it
10290-400: The tanks. Water quality should be tailored for the particular species, but most larvae will generally grow faster in warmer water. After the fertilized eggs and beginning-stage larvae have been added to the tank, they should be fed filtered or cultured algae daily, and have their water changed every-other day. This ensures no pathogens or foreign organisms enter the system and compete with or eat
10395-401: The temperature and salinity of the water are controlled (or at least monitored), so as to induce spawning and fertilization, as well as to speed the rate of maturation – which can take several years. The first step to cultivating oysters is conditioning broodstock. Broodstock are the "parent" oysters that will provide gametes for larvae. Oysters in the wild are only "ripe" with gametes for
10500-534: The tidal flats using their wheels. When the tide is in, they use a propeller to move themselves through the water. Oyster farmers in Jersey make use of similar boats. While oysters themselves can be very beneficial to their environment, the farming of oysters and other shellfish is not necessarily restorative environmentally. However, it does hold promise for relieving pressure on land-based protein sources. Production of land-based protein sources can be detrimental to
10605-590: The tide goes out. They use their muscular foot to dig into the substrate. To do this, the animal relaxes its adductor muscles and opens its shell wide to anchor itself in position while it extends its foot downwards into the substrate. Then it dilates the tip of its foot, retracts the adductor muscles to close the shell, shortens its foot and draws itself downwards. This series of actions is repeated to dig deeper. Other bivalves, such as mussels , attach themselves to hard surfaces using tough byssus threads made of collagen and elastin proteins. Some species, including
10710-558: The true oysters, the jewel boxes , the jingle shells , the thorny oysters and the kitten's paws , cement themselves to stones, rock or larger dead shells. In oysters, the lower valve may be almost flat while the upper valve develops layer upon layer of thin horny material reinforced with calcium carbonate. Oysters sometimes occur in dense beds in the neritic zone and, like most bivalves, are filter feeders. Bivalves filter large amounts of water to feed and breathe but they are not permanently open. They regularly shut their valves to enter
10815-402: The two valves and contract to close the shell. The valves are also joined dorsally by the hinge ligament , which is an extension of the periostracum. The ligament is responsible for opening the shell, and works against the adductor muscles when the animal opens and closes. Retractor muscles connect the mantle to the edge of the shell, along a line known as the pallial line . These muscles pull
10920-452: The water column. The particulate matter oysters remove are sand, clay, silt, detritus, and phytoplankton . These particulates all could possibly contain harmful contamination that originates from anthropogenic sources (the land or directly flowing into the body of water). Instead of becoming ingested by other filter feeders that are then digested by bigger organisms, oysters can sequester these possibly harmful pollutants, and excrete them into
11025-417: The young inside their mantle cavity, eventually releasing them into the water column as veliger larvae or as crawl-away juveniles. Most of the bivalve larvae that hatch from eggs in the water column feed on diatoms or other phytoplankton. In temperate regions, about 25% of species are lecithotrophic , depending on nutrients stored in the yolk of the egg where the main energy source is lipids . The longer
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