Jhenaidah ( Bengali : ঝিনাইদহ ) is a city in the Khulna Division of south-western Bangladesh . Jhenaidah is the headquarters of Jhenaidah Sadar Upazila and Jhenaidah District . The city has a population of about 140,000, making it the 19th largest city in Bangladesh. It is the fourth largest city in the Khulna division , after Khulna , Kushtia , and Jessore .
79-404: This area was once very popular for trading oysters . In the past, people of this area used to collect a huge quantity of oysters from the river bed Nabaganga and the adjacent khaals and beels . It is believed that the name of the aea might have derived from Jhinuk. Jhenaidah the largest city of Jhenaidah District came into existence probably in the middle of 18th century. Previously, it
158-465: A bed and reaching sexual maturity within a year. Oysters are filter feeders , drawing water in over their gills through the beating of cilia . Suspended plankton and non-food particles are trapped in the mucus of a gill, and from there are transported to the mouth, where they are eaten, digested, and expelled as feces or pseudofeces that fall to the bottom and remain out of the water column. Oysters feed most actively at temperatures ranging from
237-447: A cream roux . In the case of Oysters Rockefeller , preparation can be very elaborate. They are sometimes served on edible seaweed, such as brown algae . Genus Genus ( / ˈ dʒ iː n ə s / ; pl. : genera / ˈ dʒ ɛ n ər ə / ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses . In binomial nomenclature ,
316-442: A distinct family, the feathered oysters ( Pteriidae ). Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels , also yield pearls of commercial value. The largest pearl-bearing oyster is the marine Pinctada maxima , which is roughly the size of a dinner plate. Not all individual oysters produce pearls. In nature, pearl oysters produce pearls by covering
395-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as
474-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,
553-419: A minute invasive object with nacre . Over the years, the irritating object is covered with enough layers of nacre to become a pearl. The many different types, colours and shapes of pearls depend on the natural pigment of the nacre, and the shape of the original irritant. Pearl farmers can culture a pearl by placing a nucleus, usually a piece of polished mussel shell, inside the oyster. In three to seven years,
632-541: A popular treat celebrated in oyster festivals in many cities and towns. It was once assumed that oysters were only safe to eat in months with the letter 'r' in their English and French names. This myth is based in truth, in that in the Northern Hemisphere, oysters are much more likely to spoil in the warmer months of May, June, July, and August. In recent years , pathogens such as Vibrio parahaemolyticus have caused outbreaks in several harvesting areas of
711-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for
790-483: A resting state, even when they are permanently submersed. Their behaviour follows very strict circatidal and circadian rhythms according to the relative moon and sun positions. During neap tides, they exhibit much longer closing periods than during the spring tide. Some tropical oysters, such as the mangrove oyster in the family Ostreidae , grow best on mangrove roots. Low tide can expose them, making them easy to collect. The largest oyster-producing body of water in
869-449: A result of global change are also negatively impacting oysters around the world, with many impacts affecting molecular, physiological, and behavioral processes in species including Magallana gigas. Recycled oyster shells can help restore oyster reefs to provide marine life habitat that reduces flooding, and protects shorelines from storms. Shell-recycling non-profits retrieve shells from restaurants, wash and dry them, and set them in
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#1732783856241948-605: A sex ratio of 959 females per 1000 males. The city consists of a paurashava which is further divided into 9 wards and 34 Mahalla Wards & included mahallas are Jhenaidah is the road transport hub of its district. It is on the Daulatdia–Mongla Highway (N7). The stretch that runs east to Magura , about 27 kilometres (17 mi) away, was the second deadliest in Bangladesh as of 2004. The length that runs south to Jessore , about 45 kilometres (28 mi) away,
1027-583: A site where pollution was affecting beach tourism. Currently, for the installation cost of $ 3000, roughly 4.8 million liters of water are being filtered daily. In New Jersey, however, the Department of Environmental Protection refused to allow oysters as a filtering system in Sandy Hook Bay and the Raritan Bay, citing worries that commercial shellfish growers would be at risk and that members of
1106-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;
1185-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and
1264-501: Is believed to be the last-built Connecticut oyster sloop, completed in 1948. Oysters can also be collected by divers . In any case, when the oysters are collected, they are sorted to eliminate dead animals, bycatch (unwanted catch), and debris. Then they are taken to market, where they are either canned or sold live. Oysters have been cultured since at least the days of the Roman Empire . The Pacific oyster ( Magallana gigas )
1343-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms
1422-436: Is dominated by the larger Pacific oyster and Rock oyster species which are farmed year-round. Oysters are harvested by simply gathering them from their beds. In very shallow waters, they can be gathered by hand or with small rakes . In somewhat deeper water, long-handled rakes or oyster tongs are used to reach the beds. Patent tongs can be lowered on a line to reach beds that are too deep to reach directly. In all cases,
1501-746: Is estimated that one acre (0.40 ha) can produce nearly 750,000 oysters, which could filter between 57,000 to 150,000 m (2.0–5.3 million cu ft) of water daily. Also see nutrient pollution for an extended explanation of nutrient remediation . As an ecosystem engineer , oysters provide supporting ecosystem services , along with provisioning, regulating and cultural services. Oysters influence nutrient cycling , water filtration , habitat structure, biodiversity , and food web dynamics. Oyster reef habitats have been recognized as green infrastructure for shoreline protection. Assimilation of nitrogen and phosphorus into shellfish tissues provides an opportunity to remove these nutrients from
1580-543: Is held in September. In fact, in Victorian England, it was quite common for people to go to the pub and enjoy their favorite beer with some oysters. They quickly realized that the "rich, sweet, malty stouts" were great with the "briny, creamy oyster". Then brewers found that oyster shells naturally clarify a beer and they started putting crushed oyster shells into their brews. The first known brewery to start this
1659-518: Is presently the most widely grown bivalve around the world. Two methods are commonly used, release and bagging. In both cases, oysters are cultivated onshore to the size of spat, when they can attach themselves to a substrate. They may be allowed to mature further to form "seed oysters". In either case, they are then placed in the water to mature. The release technique involves distributing the spat throughout existing oyster beds, allowing them to mature naturally to be collected like wild oysters. Bagging has
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#17327838562411738-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,
1817-409: Is technically possible for an oyster to fertilize its own eggs. The gonads surround the digestive organs, and are made up of sex cells, branching tubules, and connective tissue. Once her millions of eggs are fertilized, the female discharges them into the water. The larvae develop in about six hours and exist suspended in the water column as veliger larvae for two to three weeks before settling on
1896-444: Is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified , and many are somewhat irregular in shape. Many, but not all oysters, are in the superfamily Ostreoidea . Some species of oyster are commonly consumed and are regarded as a delicacy in some localities. Some types of pearl oysters are harvested for
1975-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with
2054-695: Is the busiest segment of the highway. To the west it is connected by regional highway R745 to Chuadanga , 36 kilometres (22 mi) away. National highway N704 splits off the N7 north to Kushtia , 47 kilometres (29 mi) distant. The literacy rate (age 7 years and above) is 67.2%. Jhenaidah is known as important educational city of Khulna division . Educational institutions of Jhenaidah city are Aside from these, there are Jhenaidah Government Veterinary College , Sheikh Kamal Textile Engineering College, and Islamic University Bangladesh outside Jhenaidah municipality. Oyster All other members of: Oyster
2133-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to
2212-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;
2291-476: The Philippines , a local thorny oyster species known as Tikod amo is a favorite seafood source in the southern part of the country. Because of its good flavor, it commands high prices. Oysters breathe primarily via gills . In addition to their gills, oysters can exchange gases across their mantles , which are lined with many small, thin-walled blood vessels . A small, three-chambered heart , lying under
2370-696: The United States is the Chesapeake Bay , although these beds have decreased in number due to overfishing and pollution. Other large oyster farming areas in the US include the bays and estuaries along the coast of the Gulf of Mexico from Apalachicola, Florida , in the east to Galveston, Texas , in the west. Large beds of edible oysters are also found in Japan and Australia. In 2005, China accounted for 80% of
2449-469: The adductor muscle , pumps colorless blood to all parts of the body. At the same time, two kidneys , located on the underside of the muscle, remove waste products from the blood. Their nervous system includes two pairs of nerve cords and three pairs of ganglia . There is no evidence that oysters have a brain. While some oysters have two sexes ( European oyster and Olympia oyster ), their reproductive organs contain both eggs and sperm. Because of this, it
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2528-587: The eastern oyster ( Crassostrea virginica ) was introduced to California waters in 1875, while the Pacific oyster was introduced there in 1929. Proposals for further such introductions remain controversial. The Pacific oyster prospered in Pendrell Sound , where the surface water is typically warm enough for spawning in the summer. Over the following years, spat spread out sporadically and populated adjacent areas. Eventually, possibly following adaptation to
2607-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,
2686-655: The pearl produced within the mantle . Others, such as the translucent Windowpane oysters , are harvested for their shells. The word oyster comes from Old French oistre , and first appeared in English during the 14th century. The French derived from the Latin ostrea , the feminine form of ostreum , which is the latinisation of the Ancient Greek ὄστρεον ( ostreon ) 'oyster'. Compare ὀστέον ( osteon ) 'bone'. True oysters are members of
2765-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,
2844-526: The tides . He was so famous for this, the Romans used to say he could breed oysters on the roof of his house. In the early 19th century, oysters were cheap and mainly eaten by the working class . Throughout the 19th century, oyster beds in New York Harbor became the largest source of oysters worldwide. On any day in the late 19th century, six million oysters could be found on barges tied up along
2923-529: The United Kingdom, the town of Whitstable is noted for oyster farming from beds on the Kentish Flats that have been used since Roman times. The borough of Colchester holds an annual Oyster Feast each October, at which "Colchester Natives" (the native oyster, Ostrea edulis ) are consumed. The United Kingdom hosts several other annual oyster festivals; for example, Woburn Oyster Festival
3002-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of
3081-435: The beds by the early 20th century. Oysters' popularity has put ever-increasing demands on wild oyster stocks. This scarcity increased prices, converting them from their original role as working-class food to their current status as an expensive delicacy. In Britain, the native species ( European flat oyster ) has five years to mature and is protected by the people during their May-to-August spawning season. The current market
3160-409: The capacity to dramatically alter nitrogen levels in estuaries. In the U.S., Delaware is the only East Coast state without aquaculture, but making aquaculture a state-controlled industry of leasing water by the acre for commercial harvesting of shellfish is being considered. Supporters of Delaware's legislation to allow oyster aquaculture cite revenue, job creation, and nutrient cycling benefits. It
3239-541: The city's waterfront. They were naturally quite popular in New York City , and helped initiate the city's restaurant trade. New York's oystermen became skilled cultivators of their beds, which provided employment for hundreds of workers and nutritious food for thousands. Eventually, rising demand exhausted many of the beds. To increase production, they introduced foreign species, which brought disease; effluent and increasing sedimentation from erosion destroyed most of
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3318-549: The cultivator putting spat in racks or bags and keeping them above the bottom. Harvesting involves simply lifting the bags or rack to the surface and removing the mature oysters. The latter method prevents losses to some predators, but is more expensive. The Pacific oyster has been grown in the outflow of mariculture ponds. When fish or prawns are grown in ponds, it takes typically 10 kg (22 lb) of feed to produce 1 kg ( 2 + 1 ⁄ 4 lb) of product ( dry-dry basis). The other 9 kg (20 lb) goes into
3397-444: The eastern United States during the summer months, lending further credence to this belief. Oysters can be eaten on the half shell, raw, smoked , boiled , baked , fried , roasted , stewed , canned , pickled , steamed , or broiled , or used in a variety of drinks. Eating can be as simple as opening the shell and eating the contents, including juice. Butter and salt are often added. Poached oysters can be served on toast with
3476-807: The family Ostreidae . This family includes the edible oysters, which mainly belong to the genera Ostrea , Crassostrea , Magallana , and Saccostrea . Examples include the European flat oyster , eastern oyster , Olympia oyster , Pacific oyster , and the Sydney rock oyster . Ostreidae evolved in the Early Triassic epoch : The genus Liostrea grew on the shells of living ammonoids . Almost all shell-bearing mollusks can secrete pearls, yet most are not very valuable. Pearls can form in both saltwater and freshwater environments. Pearl oysters are not closely related to true oysters, being members of
3555-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this
3634-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,
3713-528: The genus name forms the first part of the binomial species name for each species within the genus. The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of
3792-412: The global oyster harvest. In Europe, France remained the industry leader. Common oyster predators include crabs , seabirds , starfish , and humans . Some oysters contain crabs, known as oyster crabs . Bivalves , including oysters, are effective filter feeders and can have large effects on the water columns in which they occur. As filter feeders, oysters remove plankton and organic particles from
3871-419: The high 60s to the high 70s (20–26 °C). Under ideal laboratory conditions, an oyster can filter up to 190 L (50 US gal) of water per day. Under average conditions, mature oysters filter 11–45 L (3–12 U.S. gal). Chesapeake Bay 's once-flourishing oyster population historically filtered excess nutrients from the estuary's entire water volume every three to four days. As of 2008 it
3950-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,
4029-521: The late 1880s, when the bay's population was in the billions, and watermen harvested about 910,000 m (25 million imp bsh) annually. The 2009 harvest was less than 7,300 m (200,000 imp bsh). Researchers claim the keys to the project were: The "oyster-tecture" movement promotes the use of oyster reefs for water purification and wave attenuation. An oyster-tecture project has been implemented at Withers Estuary, Withers Swash, South Carolina, by Neil Chambers-led volunteers, at
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#17327838562414108-540: The local conditions, the Pacific oyster spread up and down the coast and now is the basis of the North American west coast oyster industry. Pendrell Sound is now a reserve that supplies spat for cultivation. Near the mouth of the Great Wicomico River in the Chesapeake Bay , five-year-old artificial reefs now harbor more than 180 million native Crassostrea virginica . That is far lower than in
4187-666: The loss of half of California's Olympia oysters . Oyster reefs occupy a small fraction of their distribution prior to mass harvesting during the last three centuries. In October 2017, it was reported that underwater noise pollution can affect oysters as they close their shells when exposed to low frequencies of sounds in experimental conditions. Oysters rely on hearing waves and currents to regulate their circadian rhythms , and perception of weather events—such as rain —may induce spawning . Cargo ships , pile drivers , and explosions conducted underwater produce low frequencies that may be detected by oysters. Environmental stressors as
4266-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus
4345-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this
4424-425: The next two or three years and develop greater energy reserves, they spawn as females by releasing eggs . Bay oysters usually spawn from the end of June until mid-August. An increase in water temperature prompts a few oysters to spawn. This triggers spawning in the rest, clouding the water with millions of eggs and sperm. A single female oyster can produce up to 100 million eggs annually. The eggs become fertilized in
4503-489: The oyster can produce a perfect pearl. Since the beginning of the 20th century, when several researchers discovered how to produce artificial pearls, the cultured pearl market has far outgrown the natural pearl market. A number of bivalve molluscs (other than true oysters and pearl oysters) also have common names that include the word "oyster", usually because they either taste like or look somewhat like true oysters, or because they yield noticeable pearls. Examples include: In
4582-463: The pond and after mineralization, provides food for phytoplankton, which in turn feeds the oyster. To prevent spawning, sterile oysters are now cultured by crossbreeding tetraploid and diploid oysters. The resulting triploid oyster cannot propagate, which prevents introduced oysters from spreading into unwanted habitats. In many areas, non-native oysters have been introduced in attempts to prop up failing harvests of native varieties. For example,
4661-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for
4740-430: The public might disregard warnings and consume tainted oysters. New Jersey Baykeepers responded by changing their strategy for utilizing oysters to clean up the waterway, by collaborating with Naval Weapons Station Earle. The Navy station is under 24/7 security and therefore eliminates any poaching and associated human health risk. Oyster-tecture projects have been proposed to protect coastal cities, such as New York, from
4819-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or
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#17327838562414898-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in
4977-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,
5056-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being
5135-569: The sun for up to a year to kill bacteria. Some states encourage shell recycling by offering tax incentives. Jonathan Swift is quoted as having said, "He was a bold man that first ate an oyster". Evidence of oyster consumption goes back into prehistory, evidenced by oyster middens found worldwide. Oysters were an important food source in all coastal areas where they could be found, and oyster fisheries were an important industry where they were plentiful. Overfishing and pressure from diseases and pollution have sharply reduced supplies, but they remain
5214-424: The surface area of a flat bottom 50-fold. An oyster's mature shape often depends on the type of bottom to which it is originally attached, but it always orients itself with its outer, flared shell tilted upward. One valve is cupped and the other is flat. Oysters usually reach maturity in one year. They are protandric ; during their first year, they spawn as males by releasing sperm into the water. As they grow over
5293-529: The task is the same: the oysterman scrapes oysters into a pile, and then scoops them up with the rake or tongs. In some areas, a scallop dredge is used. This is a toothed bar attached to a chain bag. The dredge is towed through an oyster bed by a boat, picking up the oysters in its path. While dredges collect oysters more quickly, they heavily damage the beds, and their use is highly restricted. Until 1965, Maryland limited dredging to sailboats , and even since then motor boats can be used only on certain days of
5372-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for
5451-484: The threat of rising sea levels due to climate change . Additionally Oyster reef restoration has shown to increase the population of oyster beds within the oceans while also conserving the biolife within the oyster reefs. The accidental or intentional introduction of species by humans has the potential to negatively impact native oyster populations. For example, non-native species in Tomales Bay have resulted in
5530-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up
5609-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in
5688-503: The water and develop into larvae, which eventually find suitable sites, such as another oyster's shell, on which to settle. Attached oyster larvae are called spat. Spat are oysters less than 25 mm (1 in) long. Many species of bivalves, oysters included, seem to be stimulated to settle near adult conspecifics . Oysters filter large amounts of water to feed and breathe (exchange O 2 and CO 2 with water) but they are not permanently open. They regularly shut their valves to enter
5767-548: The water column. In California's Tomales Bay , native oyster presence is associated with higher species diversity of benthic invertebrates. As the ecological and economic importance of oyster reefs has become more acknowledged, restoration efforts have increased. Middens testify to the prehistoric importance of oysters as food, with some middens in New South Wales , Australia, dated at ten thousand years. They have been cultivated in Japan from at least 2000 BC. In
5846-416: The water column. Multiple studies have shown individual oysters are capable of filtering up to 190 litres (42 imp gal; 50 US gal) of water per day, and thus oyster reefs can significantly improve water quality and clarity. Oysters consume nitrogen-containing compounds ( nitrates and ammonia ), phosphates , plankton, detritus, bacteria, and dissolved organic matter, removing them from
5925-490: The water. What is not used for animal growth is then expelled as solid waste pellets, which eventually decompose into the atmosphere as nitrogen. In Maryland , the Chesapeake Bay Program had implemented a plan to use oysters to reduce the amount of nitrogen compounds entering the Chesapeake Bay by 8,600 t (9,500 short tons) per year by 2010. Several studies have shown that oysters and mussels have
6004-480: The week. These regulations prompted the development of specialized sailboats (the bugeye and later the skipjack ) for dredging. Similar laws were enacted in Connecticut before World War I and lasted until 1969. The laws restricted the harvesting of oysters in state-owned beds to vessels under sail. These laws prompted the construction of the oyster sloop-style vessel to last well into the 20th century. Hope
6083-420: Was a part of Greater Kushtia , itself once a part of Greater Nadia . According to the 2022 Bangladesh census , Jhenaidah city had a population of 140,256. According to the 2011 Bangladesh census , Jhenaidah city had 25,286 households and a population of 107,834. 18,813 (17.45%) were under 10 years of age. Jhenaidah had a literacy rate (age 7 and over) of 68.09%, compared to the national average of 51.8%, and
6162-679: Was estimated that a complete cycle would take nearly a year. A group of oysters is commonly called a bed or oyster reef . As a keystone species , oysters provide habitat for many marine species. Crassostrea and Saccostrea live mainly in the intertidal zone , while Ostrea is subtidal . The hard surfaces of oyster shells and the nooks between the shells provide places where a host of small animals can live. Hundreds of animals, such as sea anemones , barnacles , and hooked mussels , inhabit oyster reefs . Many of these animals are prey to larger animals, including fish, such as striped bass , black drum and croakers . An oyster reef can increase
6241-698: Was in 1938 at the Hammerton Brewery in London. That is where the oyster stout was first started. The French seaside resort of Cancale in Brittany is noted for its oysters, which also date from Roman times. Sergius Orata of the Roman Republic is considered the first major merchant and cultivator of oysters. Using his considerable knowledge of hydraulics , he built a sophisticated cultivation system, including channels and locks, to control
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