Shellfish is a food source and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found in freshwater. In addition, a few species of land crabs are eaten, for example Cardisoma guanhumi in the Caribbean.

Despite the name, shellfish are not a kind of fish, but are simply water-dwelling animals. Many varieties of shellfish (crustaceans in particular) are actually closely related to insects and arachnids, making up one of the main classes of the phylum Arthropoda. Cephalopods (squids, octopuses, cuttlefish) and bivalves (clams, oysters) are molluscs, as are Gastropods (aquatic species such as whelks and winkles; also land species such as snails and slugs).

Shellfish used as a food source by humans include many species of clams, mussels, oysters, winkles, and scallops. Some crustaceans that are commonly eaten are shrimp, lobsters, crayfish, and crabs.[1] Echinoderms are not as frequently harvested for food as molluscs and crustaceans; however, sea urchin roe is quite popular in many parts of the world.[2][3]

Most shellfish eat a diet composed primarily of phytoplankton and zooplankton.[4]

Shellfish are among the most common food allergens.[5]

Oysters p1040741
Raw oysters, opened, and presented on a plate


Rheinische Muscheln
Cooked mussels

The term shellfish is used both broadly and specifically. In common parlance, as in having "shellfish" for dinner, it can refer to anything from clams and oysters to lobster and shrimp. For regulatory purposes it is often narrowly defined as filter-feeding molluscs such as clams, mussels, and oyster to the exclusion of crustaceans and all else.[6]

Although the term is primarily applied to marine species, edible freshwater invertebrates such as crayfish and river mussels are also sometimes grouped under the umbrella term "shellfish".

Although their shells may differ, all shellfish are invertebrates. As non-mammalian animals that spend their entire lives in water they are "fish" in an informal sense; however the term finfish is sometimes used to distinguish fish as animals defined by having vertebrae from shellfish in modern terminology.

The word "shellfish" is both singular and plural; the rarely used "shellfishes" is sometimes employed to distinguish among various types of shellfish.[7]

Shellfish in various cuisines

Archaeological finds have shown that humans have been making use of shellfish as a food item for hundreds of thousands of years. In the present, shellfish dishes are a feature of almost all the cuisines of the world, providing an important source of protein in many cuisines around the world, especially in the countries with coastal areas.

Sakura ebi
Sakura ebi

In Japan

In the Japanese cuisine, chefs often use shellfish and their roe in different dishes. Sushi (vinegared rice, topped with other ingredients, including shellfish, fish, meat and vegetables) features both raw and cooked shellfish. Sashimi primarily consists of very fresh raw seafood, sliced into thin pieces. Both sushi and sashimi are served with soy sauce and wasabi paste (a Japanese horseradish root, a spice with extremely strong, hot flavor), thinly sliced pickled ginger root, and a simple garnish such as shiso (a kitchen herb, member of the mint family) or finely shredded daikon radish, or both.

In the United States

Lobster in particular is a great delicacy in the United States, where families in the Northeast region make them into the centerpiece of a clam bake, usually for special occasions. Lobsters are eaten on much of the East Coast; the American lobster ranges from Newfoundland down to about the Carolinas, but is most often associated with Maine. A typical meal involves boiling the lobster with some slight seasoning and then serving it with drawn butter, baked potato, and corn on the cob.

Clamming is done both commercially and recreationally along the Northeast coastline of the US. Various type of clams are incorporated into the cuisine of New England. The soft-shelled clam is eaten either fried or steamed (and then called "steamers"). Many types of clams can be used for clam chowder, but the quahog, a hard shelled clam also known as a chowder clam, is often used because the long cooking time softens its tougher meat.

The Chesapeake Bay and Maryland region has generally been associated more with crabs, but in recent years the area has been trying to reduce its catch of blue crabs, as wild populations have been depleted. This has not, however, stemmed the demand: Maryland-style crabcakes are still a well known treat in crabhouses all over the bay, though the catch now comes from points farther south.

Scallop sandwich (1)
Scallop sandwich served in San Diego

In the Southeast, and particularly the gulf states, shrimping is an important industry. Copious amounts of shrimp are harvested each year in the Gulf of Mexico and the Atlantic Ocean to satisfy a national demand for shrimp. Locally, prawns and shrimp are often deep fried; in the Cajun and Creole kitchens of Louisiana, shrimp and prawns are a common addition to traditional recipes like jambalaya and certain stews. Crawfish[8] are a well known and much eaten delicacy there, often boiled in huge pots and heavily spiced.

In many major cities with active fishing ports, raw oyster bars are also a feature of shellfish consumption. When served freshly shucked (opened) and iced, one may find a liquid inside the shell, called the liquor. Some believe that oysters have the properties of an aphrodisiac.[9]

Inter-tidal herbivorous shellfish such as mussels and clams can help people reach a healthy balance of omega-3 and omega-6 fats in their diets, instead of the current Western diets.[10] For this reason, the eating of shellfish is often encouraged by dietitians. Shellfish are also a rich source of the amino acid taurine.

Around the world

Gambas in XXmiglia market
Large shrimp or prawns for sale in Italy
Cooked Snail Found In Rajang River
A dish of cooked freshwater nerites from the Rajang River, Sarawak, Malaysia

Shellfish is a common part of indigenous cuisines throughout the philippines.

Some popular dishes using shellfish:

Religious dietary restrictions

The Torah forbids the consumption of shellfish (i.e. the only permitted seafood is fish with fins and scales), in the books of Leviticus and Deuteronomy.[11] Jews (of all religious traditions) who fully observe the dietary laws thus do not eat shellfish. Neither do Seventh-day Adventists, who follow Jewish dietary law because the Torah is part of their Old Testament. Islamic dietary laws are divided on the question. Most Muslim traditions consider some or all shellfish to be halal while some others classify all shellfish as haram.


While estimates vary from shellfish, approximately 1% of the population is estimated to suffer from seafood allergy, which is more common in teenage and adult life than very early childhood. An estimated 20% will grow out of their allergy with time.

Toxic content

Some shellfish, such as whelk, contain arsenic. A sample of whelk was found to have a total content of arsenic at 15.42 mg/kg of which 1% is inorganic arsenic.[12]

Shellfish caught in Alaska can lead to Paralytic Shellfish Poisoning (PSP).[13] PSP is caused by toxins released by dinoflagellate, a type of algae, which are extremely poisonous (1000 times more potent than cyanide) and can lead to death by paralyzing the breathing muscles. Due to warming oceans algae blooms have become more widespread,[14] thereby increasing the likelihood of intoxications of various types.

See also



  1. ^ "Shellfish climbs up the popularity ladder; the category is gaining chefs' attention for one-of-a-kind signature menu items". HighBeam Research. Archived from the original on 2012-11-05. Retrieved 2009-08-25.
  2. ^ Fabricant, Florence (1998). "Sea urchin makes waves, popularity increases on American menus". Nation's Restaurant News via BNET. Archived from the original on 2012-05-24. Retrieved 2009-08-25.
  3. ^ "The sea urchin market in Japan". Marine Fisheries Review via BNET. 1989. Archived from the original on 2012-05-24. Retrieved 2009-08-25.
  4. ^ "Manual on the Production and Use of Live Food for Aquaculture". Food and Agriculture Organization of the United Nations. Retrieved 2009-08-25.
  5. ^ "Shellfish Alergies". Cleveland Clinic. Retrieved 2009-08-25.
  6. ^ Maryland Shellfish Harvesting Areas Archived 11 October 2006 at the Wayback Machine, Maryland Department of the Environment
  7. ^ Festing, Sally (1999). Fishermen: A Community living from the Sea (Revised ed.). Stamford: Shaun Tyas. p. 119. ISBN 978-1-900289-22-1.
  8. ^ "Crawfish Nutritional Facts"
  9. ^ O'Connor, Anahad (2005-05-10). "The Claim: Oysters Are Aphrodisiacs". The New York Times. ISSN 0362-4331. Retrieved 2018-01-31.
  10. ^ Robson, Anthony (2006). "Shellfish view of omega-3 and sustainable fisheries". Nature. 444 (7122): 1002. doi:10.1038/4441002d.
  11. ^ Leviticus 11:9-12
  12. ^ "82/05 October 2005 Arsenic in fish and shellfish" (PDF). 2010-09-08. Retrieved 2013-04-06.
  13. ^
  14. ^


External links

Algal bloom

An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems, and is recognized by the discoloration in the water from their pigments. Cyanobacteria were mistaken for algae in the past, so cyanobacterial blooms are sometimes also called algal blooms. Blooms which can injure animals or the ecology are called "harmful algal blooms" (HAB), and can lead to fish die-offs, cities cutting off water to residents, or states having to close fisheries. Also, a bloom can block out the sunlight from other organisms, and deplete oxygen levels in the water. Also, some algae secrete poisons into the water.

Amnesic shellfish poisoning

Amnesic shellfish poisoning (ASP) is an illness caused by consumption of the marine biotoxin called domoic acid. In mammals, including humans, domoic acid acts as a neurotoxin, causing permanent short-term memory loss, brain damage, and death in severe cases.

This toxin is produced naturally by marine diatoms belonging to the genus Pseudo-nitzschia and the species Nitzschia navis-varingica. When accumulated in high concentrations by shellfish during filter feeding, domoic acid can then be passed on to birds, marine mammals, and humans by consumption of the contaminated shellfish.Although human illness due to domoic acid has only been associated with shellfish, the toxin can bioaccumulate in many marine organisms that consume phytoplankton, such as anchovies and sardines. Intoxication by domoic acid in nonhuman organisms is frequently referred to as domoic acid poisoning.

Andalusian cuisine

Andalusian cuisine is the cuisine of Andalusia, Spain. Notable dishes include gazpacho, fried fish (often called pescaíto frito in the local vernacular), the jamones of Jabugo, Valle de los Pedroches and Trevélez, and the wines of Jerez, particularly sherry.


Azaspiracids (AZA) are a group of polycyclic ether marine algal toxins produced by the small dinoflagellate Azadinium spinosum that can accumulate in shellfish and thereby cause illness in humans.Azaspiracid was first identified in the 1990s following an outbreak of human illness in the Netherlands that was associated with ingestion of contaminated shellfish originating from Killary Harbour, Ireland.

To date, over 20 AZA analogues have been identified in phytoplankton and shellfish. Over the last 15 years, AZAs have been reported in shellfish from many coastal regions of western Europe, Northern Africa, South America, and North America. In addition, AZAs have been found in Japanese sponges and Scandinavian crabs. Not surprisingly, the global distribution of AZAs appears to correspond to the apparent wide spread occurrence of Azadinium. Empircal evidence is now available that unambiguously demonstrates the accumulation of AZAs in shellfish via direct feeding on AZA-producing A. spinosum.

Diarrhetic shellfish poisoning

Diarrhetic shellfish poisoning (DSP) is one of the four recognized symptom types of shellfish poisoning, the others being paralytic shellfish poisoning, neurotoxic shellfish poisoning and amnesic shellfish poisoning.

As the name suggests, this syndrome manifests itself as intense diarrhea and severe abdominal pains. Nausea and vomiting may sometimes occur too.

DSP and its symptoms usually set in within about half an hour of ingesting infected shellfish, and last for about one day. A recent case in France, though, with 20 people consuming oysters manifested itself after 36 hours. The causative poison is okadaic acid, which inhibits intestinal cellular de-phosphorylation. This causes the cells to become very permeable to water and causes profuse, intense diarrhea with a high risk of dehydration. As no life-threatening symptoms generally emerge from this, no fatalities from DSP have ever been recorded.

Domoic acid

Domoic acid (DA) is a kainic acid analog neurotoxin that causes amnesic shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, sardines, and anchovies. When sea lions, otters, cetaceans, humans, and other predators eat contaminated animals, poisoning may result. Exposure to this compound affects the brain, causing seizures, and possibly death.

Fish as food

Many species of fish are consumed as food in virtually all regions around the world. Fish has been an important source of protein and other nutrients for humans from time immemorial.

In culinary and fishery contexts, fish may include shellfish, such as molluscs, crustaceans and echinoderms. English does not distinguish between fish as an animal and the food prepared from it, as it does with pig vs. pork or cow vs. beef. Some other languages do, as in the Spanish peces versus pescado. The modern English word for fish comes from the Old English word fisc (plural: fiscas) which was pronounced as it is today. English also has the term seafood, which covers fish found in the seas and oceans as well as other marine life used as food.

Gathering seafood by hand

Gathering seafood by hand can be as easy as picking shellfish or kelp up off the beach, or doing some digging for clams or crabs, or perhaps diving under the water for abalone or lobsters.

Shellfish can be collected from intertidal areas using a spade or rake and put through a sieve to extract the ones of marketable size.

Seafood can be found in coastal zones as well as rivers and lakes around the world. Seafood suitable for gathering by hand includes aquatic invertebrates such as molluscs, crustaceans, and echinoderms, as well as aquatic plants. Some molluscs (shellfish) commonly gathered are oysters, clams, scallops, and cockles. Some crustaceans commonly gathered are lobster, crayfish, and crabs. A common plant gathered is kelp. Echinoderms are not gathered as much as mollusks and crustaceans. In Asia, sea cucumbers and sea urchins are gathered. In parts of the United States, mainly the South, catfish, primarily of the flathead species, are occasionally caught by hand in a technique most often known as noodling.

Very little or no specialized equipment is required to gather many of these sea foods. Evidence for shellfish consumption in prehistory should be apparent, since the discarded shell can remain for long periods. In fact, the earliest evidence for shellfish consumption dates to a 300,000-year-old site in France called Terra Amata. This is a hominid site, as modern Homo sapiens did not appear until around 50,000 years ago. The importance of shellfish in prehistoric diet has been the source of much debate in archaeology. Sometimes they are referred to as a famine food and their nutritional value is played down at the expense of terrestrial or non-marine food sources.Some shellfish are gathered by diving. Pearl diving is the practice of hunting for oysters by free-diving to depths to 30 m. Abalone are also gathered by diving. Divers can also catch lobsters by hand.


Gumbo (French: Gombo) is Creole dish popular in the U.S. state of Louisiana, and is the official state dish. Gumbo consists primarily of a strongly-flavored stock, meat or shellfish, a thickener, and what Louisianians call the "Holy Trinity" of vegetables, namely celery, bell peppers, and onions. Gumbo is often categorized by the type of thickener used, whether roux, okra or filé powder (dried and ground sassafras leaves). The dish derived its name from Africa meaning okra, which may have derived the name from a source such as the Choctaw word for filé (kombo).

Gumbo can be made with or without okra or filé powder. The preferred method in the historical New Orleans variation is with a French dark roux. The flavor of the dish has its origins in many cultures. Creole gumbo generally contains shellfish, and a dark roux, filé, or both. Tomatoes are traditionally found in Creole gumbo and frequently appear in New Orleans cuisine. Cajun gumbo is generally based on a dark roux and is made with shellfish or fowl. Sausage or ham is often added to gumbos of either variety. After the base is prepared, vegetables are cooked down, and then meat is added. The dish simmers for a minimum of three hours, with shellfish and some spices added near the end. If desired, filé powder is added after the pot is removed from heat. Gumbo is traditionally served over rice. A third, lesser-known variety, the meatless gumbo z'herbes, is essentially a gumbo of slow-cooked greens.

The dish combines ingredients and culinary practices of several cultures, including African, French, Spanish, German, and Choctaw. Gumbo may have been based on traditional native dishes, or may be a derivation of the French dish bouillabaisse, or Choctaw stew, but most likely all of these dishes contributed to the original recipe. It was first described in 1802, and was listed in various cookbooks in the latter half of the 19th century. The dish gained more widespread popularity in the 1970s, after the United States Senate dining room added it to the menu in honor of Louisiana Senator Allen Ellender. The popularity of chef Paul Prudhomme in the 1980s spurred further interest in the dish.

List of Statutory Instruments of Scotland, 2000

This is an incomplete list of Scottish Statutory Instruments in 2000.

List of types of seafood

The following is a list of types of seafood. Seafood is any form of sea life regarded as food by humans. It prominently includes fish, shellfish, and roe. Shellfish include various species of molluscs, crustaceans, and echinoderms. Historically, sea mammals such as whales and dolphins have been consumed as food, though that happens to a lesser extent in modern times. Edible sea plants, such as some seaweeds and microalgae, are widely eaten as seafood around the world, especially in Asia (see the category of sea vegetables). In North America, although not generally in the United Kingdom, the term "seafood" is extended to fresh water organisms eaten by humans, so any edible aquatic life may be broadly referred to as seafood.

Neurotoxic shellfish poisoning

Neurotoxic shellfish poisoning is caused by the consumption of shellfish contaminated by breve-toxins or brevetoxin analogs.Symptoms in humans include vomiting and nausea and a variety of neurological symptoms such as slurred speech. No fatalities have been reported but there are a number of cases which led to hospitalization.

Paralytic shellfish poisoning

Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks (such as mussels, clams, oysters and scallops). These shellfish are filter feeders and accumulate neurotoxins, chiefly saxitoxin, produced by microscopic algae, such as dinoflagellates, diatoms, and cyanobacteria. Dinoflagellates of the genus Alexandrium are the most numerous and widespread saxitoxin producers and are responsible for PSP blooms in subarctic, temperate, and tropical locations. The majority of toxic blooms have been caused by the morphospecies Alexandrium catenella, Alexandrium tamarense, and Alexandrium fundyense, which together comprise the A. tamarense species complex. In Asia, PSP is mostly associated with the occurrence of the species Pyrodinium bahamense.Also some pufferfish, including chamaeleon puffer, contain saxitoxin, making their consumption hazardous.

Red tide

Red tide is a common name for algal blooms, which are large concentrations of aquatic microorganisms, such as protozoans and unicellular algae (e.g. dinoflagellates and diatoms). The upwelling of nutrients from the sea floor, often following massive storms, provides for the algae and triggers bloom events. Harmful algal blooms can occur worldwide, and natural cycles can vary regionally.The growth and persistence of an algal bloom depends on wind direction and strength, temperature, nutrients, and salinity. Red tide species can be found in oceans, bays, and estuaries, but they cannot thrive in freshwater environments. Certain species of phytoplankton and dinoflagellates found in red tides contain photosynthetic pigments that vary in color from brown to red. When the algae are present in high concentrations, the water may appear to be discolored or murky. The most conspicuous effects of red tides are the associated wildlife mortalities and harmful human exposure. The production of natural toxins such as brevetoxins and ichthyotoxins are harmful to marine life.


Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin (PST). Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic shellfish poisoning (PSP).

The term saxitoxin originates from the genus name of the butter clam (Saxidomus) from which it was first isolated. But the term saxitoxin can also refer to the entire suite of more than 50 structurally related neurotoxins (known collectively as "saxitoxins") produced by algae and cyanobacteria which includes saxitoxin itself (STX), neosaxitoxin (NSTX), gonyautoxins (GTX) and decarbamoylsaxitoxin (dcSTX).

Saxitoxin has a large environmental and economic impact, as its presence in bivalve shellfish such as mussels, clams, oysters and scallops frequently leads to bans on commercial and recreational shellfish harvesting in many temperate coastal waters around the world including northeastern and western United States, western Europe, east Asia, Australia, New Zealand and South Africa. In the United States, paralytic shellfish poisoning has occurred in California, Oregon, Washington, Alaska, and New England.

Scraper (kitchen)

A kitchen scraper is a kitchen implement made of metal, plastics (such as polyethylene, nylon, or polypropylene), wood, rubber or silicone rubber. In practice, one type of scraper is often interchanged with another or with a spatula (thus scrapers are often called spatulas) for some of the various uses.


Seafood is any form of sea life regarded as food by humans. Seafood prominently includes fish and shellfish.

Shellfish include various species of molluscs, crustaceans, and echinoderms. Historically, sea mammals such as whales and dolphins have been consumed as food, though that happens to a lesser extent in modern times. Edible sea plants, such as some seaweeds and microalgae, are widely eaten as seafood around the world, especially in Asia (see the category of sea vegetables). In North America, although not generally in the United Kingdom, the term "seafood" is extended to fresh water organisms eaten by humans, so all edible aquatic life may be referred to as seafood. For the sake of completeness, this article includes all edible aquatic life.

The harvesting of wild seafood is usually known as fishing or hunting, and the cultivation and farming of seafood is known as aquaculture, or fish farming in the case of fish. Seafood is often distinguished from meat, although it is still animal and is excluded in a vegetarian diet. Seafood is an important source of protein in many diets around the world, especially in coastal areas.

Most of the seafood harvest is consumed by humans, but a significant proportion is used as fish food to farm other fish or rear farm animals. Some seafoods (kelp) are used as food for other plants (fertilizer). In these ways, seafoods are indirectly used to produce further food for human consumption. Products, such as oil and spirulina tablets, are also extracted from seafoods. Some seafood is fed to aquarium fish, or used to feed domestic pets, such as cats. A small proportion is used in medicine, or is used industrially for non-food purposes (leather).

Shellfish poisoning

Shellfish poisoning includes four (4) syndromes that share some common features and are primarily associated with bivalve molluscs (such as mussels, clams, oysters and scallops.) These shellfish are filter feeders and, therefore, accumulate toxins produced by microscopic algae, such as cyanobacteria, diatoms and dinoflagellates.


A toxin is a poisonous substance produced within living cells or organisms; synthetic toxicants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived from the word toxic.Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their toxicity, ranging from usually minor (such as a bee sting) to almost immediately deadly (such as botulinum toxin).

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