Hard clam

Thehard clam(Mercenaria mercenaria), also known as theround clam,hard-shell(orhard-shelled)clam, or thequahog,is an ediblemarinebivalvemolluskthat is native to the eastern shores ofNorth AmericaandCentral AmericafromPrince Edward Islandto theYucatán Peninsula. It is one of many unrelated edible bivalves that in the United States are frequently referred to simply asclams. Older literature sources may use the systematic nameVenus mercenaria; this species is in the familyVeneridae, the venus clams.
Confusingly, the "ocean quahog" is a different species,Arctica islandica, which, although superficially similar in shape, is in a different family of bivalves: it is rounder than the hard clam, usually has a blackperiostracum, and there is nopallial sinusin the interior of the shell.
The hard clam has many alternativecommon names. It is also known as the Northern quahog, round clam, or chowder clam.
In fish markets, there are specialist names for different sizes of this species of clam. The smallest legally harvestable clams are calledcountnecksorpeanuts, next size up arelittlenecks, thentopnecks. Above that are thecherrystones, and the largest are calledquahogsorchowder clams.
The most distinctive of these names isquahog(/ˈkoʊhɒɡ/KOH-hog,/ˈkwɔːhɒɡ/KWAW-hog, or/kwəˈhɒɡ/kwə-HOG, also speltquahaug,quohogorcohog).The word comes from theNarragansettword "poquauhock", which is similar inWampanoagand some otherAlgonquian languages; it is first attested in North American English in 1794.Native polities on the eastern Atlantic seaboard made valuable beads calledwampumfrom the shells, especially those colored purple; the species namemercenariais related to theLatinword for commerce. Today people living in coastal New England still use Algonquian words for the clam, as they have done for thousands of years.
In many areas whereaquacultureis important, clam farmers have bred specialized versions of these clams with distinctions needed for them to be distinguished in the marketplace. These are quite similar to common "wild type"Mercenariaclams, except that their shells bear distinctive markings. These are known as thenotatastrain of quahogs, which occur naturally in low numbers wherever quahogs are found.
Hard clams are quite common throughoutNew England, north intoCanada, and all down theEastern seaboardof theUnited StatestoFlorida; but they are particularly abundant betweenCape CodandNew Jersey, where seeding and harvesting them is an important commercial form ofaquaculture. For example, the species is an important member of the suspension-feeding,benthicfauna of the lowerChesapeake Bay.
Rhode Islandis situated right in the middle of "quahog country" and has supplied a quarter of the U.S.'s total annual commercial quahog catch. The quahog is theofficial shellfishof the U.S. state ofRhode Island. The species has also beenintroducedand is farmed on thePacificcoast of North America and inGreat Britainand continentalEurope. It reproduces sexually by females and males sheddinggametesinto the water.
Quahog parasite unknown (QPX)is aparasitethat affects the hard shell clamMercenaria mercenaria. While little is known about the disease, research is currently under way in several laboratories.This research is fueled by the need to informaquaculturists, who suffer financially because of the mortality rates in clams that QPX inflicts and the ensuing years in which runs must be leftfallowto clear the disease. It was discovered along the coast ofCape Cod, Massachusetts in 1995.
Quahog parasite X (or quahog parasite unknown [QPX]) disease of the hard clamMercenaria mercenariais caused by a poorly known protistan parasite. Its DNA sequence analysis places the QPX parasite among thethraustochytridstramenopiles. The QPX parasite is unicellular and possesses at least one flagellum, like most other stramenopile organisms. Thraustochytrids are common protists in marine sediments and the water column, but only a few thraustochytrids are known as parasites of marine animals. Although QPX disease was first recorded on the Atlantic coast of Canada in the early 1960s, it did not become a major economic problem until its appearance in cultured clams at Prince Edward Island, Massachusetts in 1992, and Virginia in 1997. Infected clams are characterized by the presence of blisters or pustules in the mantle and later by gaping and death.
In coastal areas of the New England states, Long Island, and New Jersey, restaurants known asraw barsor clam bars specialize in serving littlenecks and topnecks raw on an opened half-shell, usually with acocktail saucewithhorseradish, and often withlemon. Sometimes littlenecks are steamed and dipped in butter, though not as commonly as theirsoft-shelled clamcousin the "steamer". Littlenecks are often found in-the-shell in sauces, soups, stews, andclams casino, or substituted for European varieties such as thecocklein southern European seafood dishes. The largest clams are quahogs or chowders and cherrystones; they have the toughest meat and are used in such dishes asclam chowder,clam cakes, andstuffed clams, or are minced and mixed into dishes that use the smaller, more tender clams.
Historically,Native Americansused the quahog as a component inwampum, the shell beads exchanged in theNorth American fur trade.TheNarragansettsused the hard clam for food and ornaments.
A population of hard clams exists inSouthampton WaterinHampshire,England. Originally bred in the warm water outflows atSouthampton Power Stationfor use as eel bait, the population became self-sustaining and can now be found in Southampton Water and has also spread toPortsmouth HarbourandLangstone Harbour.
The term "red tide" refers to an accumulation of a toxin, such assaxitoxin, produced by marine algae.Filter-feeding shellfish are affected, such as clams, oysters, and mussels.As they filter microorganisms, clams ingestK. brevisalgae. This algae accumulates in the clams' tissues and is toxic to humans when they are consumed. The toxin affects the humancentral nervous system.Eating contaminated shellfish, raw or cooked, can be fatal.Some other kinds of algal blooms make the seawater appear red, but red tide blooms do not always discolor the water, nor are they related to tides.