Hard clam
Encyclopedia
The hard clam also known as a quahog (or quahaug), round clam, or hard-shell (or hard-shelled) clam, is an edible marine
bivalve mollusk which is native to the eastern shores of North America
, from Prince Edward Island
to the Yucatán Peninsula
. It is one of many unrelated edible bivalves which in the United States are frequently referred to simply as clam
s, as in the expression "clam digging
". Older literature sources may use the systematic name Venus mercenaria; this species is indeed in the family Veneridae
, 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 black periostracum
, and there is no pallial sinus in the interior of the shell.
s. 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 called countnecks, next size up are littlenecks, then topnecks. Above that are the cherrystones, and the largest are called quahogs or chowder clams.
Of all these names, the most distinctive is quahog (icon , ˈ , or k ). This name comes from the Narragansett
word "poquauhock" – the word is similar in Wampanoag and some other Algonquian languages
– and is first attested in North American English in 1794. As New England Indians made valuable beads called wampum
from the shells, especially those colored purple, the species name mercenaria is related to the Latin
word for commerce.
In many areas where aquaculture
is 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' Mercenaria clams, except that their shells bear distinctive markings; for example those from Wellfleet, Massachusetts
and elsewhere have pronounced wavy or zigzag chestnut-colored lines on their shells, reminiscent of a line of W's running across the shell. These are known as the notata strain of quahogs, which occur naturally in low numbers wherever quahogs are found.
Hard clams are quite common throughout New England
, north into Canada
, and all down the Eastern seaboard
of the United States
to Florida
, but are particularly abundant between Cape Cod
and New Jersey
, where seeding and harvesting them is an important commercial form of aquaculture
; for example, the species is an important member of the suspension-feeding, benthic fauna of the lower Chesapeake Bay
, while Rhode Island
, situated right in the middle of "quahog country," has supplied a quarter of the U.S.'s total annual commercial quahog catch. The quahog is the official shellfish of the U.S. state of Rhode Island
. The species has also been introduced
and is farmed on the Pacific coast of North America and in Great Britain
and continental Europe
. It reproduces sexually by females and males shedding gametes into the water.
In coastal areas of New England, New York, and New Jersey, restaurants known as raw bars or clam bars specialize in serving littlenecks and topnecks raw on an opened half-shell, usually with a cocktail sauce
with horseradish
, and often with lemon
. Sometimes, littlenecks are steamed and dipped in butter, though not as commonly as their soft-shelled clam
cousin, the "steamer." Littlenecks are often found in-the-shell in sauces, soups, stews, clams casino
or substituted for European varieties such as the cockle
in southern European seafood dishes. The largest clams, quahogs or chowders and cherrystones, which have the toughest meat, are used in such dishes as clam chowder
, clam cakes
and stuffed clam
s, or are minced and mixed into dishes that use the smaller, more tender clams.
" refers to an accumulation of a toxin produced by marine algae. Filter-feeding shellfish – such as clams, oysters, and mussels – are affected. The toxin affects the human central 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.
Clams bought from a market should always be safe, as commercial harvesters are extremely careful about red tides: they close beds that are even remotely threatened, and keep them closed for up to three or four weeks after they are clean of any red tide. Commercial clam fishers who are known to break these rules will receive a major fine in the first instance, and will most likely have their license to harvest or sell clams revoked; furthermore they are liable for any damages. Clam harvesters who violate the sanitary laws in New York face potential jail terms.
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
bivalve mollusk which is native to the eastern shores of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, from Prince Edward Island
Prince Edward Island
Prince Edward Island is a Canadian province consisting of an island of the same name, as well as other islands. The maritime province is the smallest in the nation in both land area and population...
to the Yucatán Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
. It is one of many unrelated edible bivalves which in the United States are frequently referred to simply as clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, as in the expression "clam digging
Clam digging
Clam digging is a common means of harvesting clams from below the surface of the tidal mud flats where they live. It is done both recreationally and commercially...
". Older literature sources may use the systematic name Venus mercenaria; this species is indeed in the family Veneridae
Veneridae
The Veneridae or venerids, also known as the Venus clams, are a very large family of minute to large, saltwater clams, marine bivalve molluscs. There are over 500 living species of venerid bivalves, most of which are edible, and many of which are exploited as a food source.Many of the most...
, the venus clams.
Confusingly, the "ocean quahog" is a different species, Arctica islandica
Arctica islandica
Arctica islandica, commonly known as the ocean quahog, is an edible marine bivalve mollusk native to the North Atlantic ocean, which is harvested commercially...
, which, although superficially similar in shape, is in a different family of bivalves: it is rounder than the hard clam, usually has black periostracum
Periostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
, and there is no pallial sinus in the interior of the shell.
Alternative names
The hard clam has many alternative common nameCommon name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s. 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 called countnecks, next size up are littlenecks, then topnecks. Above that are the cherrystones, and the largest are called quahogs or chowder clams.
Of all these names, the most distinctive is quahog (icon , ˈ , or k ). This name comes from the Narragansett
Narragansett language
Narragansett is an extinct Algonquian language formerly spoken in most of what is today Rhode Island by the Narragansett people. It was closely related to the other Algonquian languages of southern New England like Massachusett and Mohegan-Pequot...
word "poquauhock" – the word is similar in Wampanoag and some other Algonquian languages
Algonquian languages
The Algonquian languages also Algonkian) are a subfamily of Native American languages which includes most of the languages in the Algic language family. The name of the Algonquian language family is distinguished from the orthographically similar Algonquin dialect of the Ojibwe language, which is a...
– and is first attested in North American English in 1794. As New England Indians made valuable beads called wampum
Wampum
Wampum are traditional, sacred shell beads of the Eastern Woodlands tribes of the indigenous people of North America. Wampum include the white shell beads fashioned from the North Atlantic channeled whelk shell; and the white and purple beads made from the quahog, or Western North Atlantic...
from the shells, especially those colored purple, the species name mercenaria is related to the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word for commerce.
In many areas where aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
is 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' Mercenaria clams, except that their shells bear distinctive markings; for example those from Wellfleet, Massachusetts
Wellfleet, Massachusetts
Wellfleet is a New England town in Barnstable County, Massachusetts, United States. Located halfway between the "tip" and "elbow" of Cape Cod, Massachusetts, the town had a population of 2,749 at the 2000 census, which swells nearly sixfold during the summer...
and elsewhere have pronounced wavy or zigzag chestnut-colored lines on their shells, reminiscent of a line of W's running across the shell. These are known as the notata strain of quahogs, which occur naturally in low numbers wherever quahogs are found.
Distribution
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
, north into Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, and all down the Eastern seaboard
East Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, but are particularly abundant between Cape Cod
Cape Cod
Cape Cod, often referred to locally as simply the Cape, is a cape in the easternmost portion of the state of Massachusetts, in the Northeastern United States...
and New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, where seeding and harvesting them is an important commercial form of aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
; for example, the species is an important member of the suspension-feeding, benthic fauna of the lower Chesapeake Bay
Chesapeake Bay
The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...
, while Rhode Island
Rhode Island
The state of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...
, situated right in the middle of "quahog country," has supplied a quarter of the U.S.'s total annual commercial quahog catch. The quahog is the official shellfish of the U.S. state of Rhode Island
Rhode Island
The state of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...
. The species has also been introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
and is farmed on the Pacific coast of North America and in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
and continental Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. It reproduces sexually by females and males shedding gametes into the water.
QPX
Quahog Parasite Unknown (QPX) is a parasite that affects Mercenaria mercenaria. While little is known about the disease, research is currently under way in several laboratories. This research is fueled by the need to inform aquaculturists, who suffer financially because of the mortality rates in clams that QPX inflicts and the ensuing years in which runs must be left fallow to clear the disease.Culinary use
Cocktail sauce
Cocktail sauce is one of several types of cold or room temperature sauces often served as part of the dish referred to as seafood cocktail or as a condiment with other seafoods. In America it generally consists of ketchup mixed with prepared horseradish. Some restaurants use chili sauce, a spicier...
with horseradish
Horseradish
Horseradish is a perennial plant of the Brassicaceae family, which also includes mustard, wasabi, broccoli, and cabbages. The plant is probably native to south eastern Europe and the Arab World , but is popular around the world today...
, and often with lemon
Lemon
The lemon is both a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The fruit is used for culinary and non-culinary purposes throughout the world – primarily for its juice, though the pulp and rind are also used, mainly in cooking and baking...
. Sometimes, littlenecks are steamed and dipped in butter, though not as commonly as their soft-shelled clam
Soft-shell clam
Soft-shell clams, scientific name Mya arenaria, popularly called "steamers", "softshells", "longnecks", "piss clams", "Ipswich clams", or "Essex clams" are a species of edible saltwater clam, a marine bivalve mollusk in the family Myidae....
cousin, the "steamer." Littlenecks are often found in-the-shell in sauces, soups, stews, clams casino
Clams casino
Clams casino is a clam "on the halfshell" dish with breadcrumbs and bacon. It originated in Rhode Island in the United States. It is often served as an appetizer in New England and is served in variations nationally.-Ingredients:...
or substituted for European varieties such as the cockle
Cockle (bivalve)
Cockle is the common name for a group of small, edible, saltwater clams, marine bivalve molluscs in the family Cardiidae.Various species of cockles live in sandy sheltered beaches throughout the world....
in southern European seafood dishes. The largest clams, quahogs or chowders and cherrystones, which have the toughest meat, are used in such dishes as clam chowder
Clam chowder
Clam chowder is any of several chowders containing clams and broth. Along with the clams, diced potato is common, as are onions, which are occasionally sauteed in the drippings from salt pork or bacon. Celery is frequently used. Other vegetables are uncommon, but small carrot strips might...
, clam cakes
Clam cakes
Clam cakes are a New England food, most common in Rhode Island, Massachusetts and Maine. Each clam cake is a deep fried ball of dough with chopped clam and various other ingredients. The batter is made from flour, milk, clam juice, eggs and a leavening agent, typically baking powder...
and stuffed clam
Stuffed clam
Stuffed clams are also known as stuffies. They are popular in New England and consist of a breadcrumb and minced clam mixture that is baked on the half shell of a quahog hard shell clam. Other ingredients typically found in the basic breadcrumb mixture are: meat such as sausage, bacon or chorizo,...
s, or are minced and mixed into dishes that use the smaller, more tender clams.
Clams and red tide
The term "red tideRed tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...
" refers to an accumulation of a toxin produced by marine algae. Filter-feeding shellfish – such as clams, oysters, and mussels – are affected. The toxin affects the human central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. 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.
Clams bought from a market should always be safe, as commercial harvesters are extremely careful about red tides: they close beds that are even remotely threatened, and keep them closed for up to three or four weeks after they are clean of any red tide. Commercial clam fishers who are known to break these rules will receive a major fine in the first instance, and will most likely have their license to harvest or sell clams revoked; furthermore they are liable for any damages. Clam harvesters who violate the sanitary laws in New York face potential jail terms.
Further reading
- Kraeuter, J.N. and M. Castagna (eds)., 2001. The Biology of the Hard Clam. Elsevier Science, Amsterdam. 772 pp. ISBN 0444819088 Google Books
- Perrigault M., Tanguy A. & Allam B. 2009. Identification and expression of differentially expressed genes in the hard clam, Mercenaria mercenaria, in response to quahog parasite unknown (QPX). BMC Genomics 2009, 10:377.