Shellfish is a
culinaryand fisheriesterm for those aquatic invertebrateanimals that are used as food: various species of molluscs, crustaceans, and echinoderms. Although the word is primarily used as a term for marine species, freshwateredible invertebrates (such as crayfishand river musselsetc) are also sometimes grouped with the marine species under the umbrella concept of "shellfish".
Almost all shellfish have a hard exterior or
exoskeleton, known as a shell, hence the first part of the word. The second word fragment "fish", is here used in the archaic sense, to mean an animal that lives its whole life in water. However, these invertebrate animals are not " fish" in the modern sense of the word, and therefore the term "finfish" or "fin fish" is sometimes used to distinguish ordinary ( vertebrate) fishfrom shellfish.
The word "shellfish" is used as singular and plural, but the less common plural "shellfishes" is sometimes used when referring to various "types of shellfish". [p119, "Fishermen, a community living from the sea", by Sally Festing,
Shaun Tyas, Stamford, 1999, ISBN 1 9000289 22 9]
Molluscs commonly used as food include many
speciesof clams, mussels, oysters, winkles, and scallops. Some crustaceans commonly eaten are various species of shrimp, prawn, lobster, crayfish, and crabs. Echinoderms are not as frequently eaten as molluscs and crustaceans, but the roeof sea urchins is quite popular in many parts of the world, and in Asia, sea cucumbers (echinoderms which have no shell) are gathered as a food item.
Other edible mollusks such as shell-less
cephalopods( squid octopusand cuttlefish) and terrestrial snails which do have a shell such as escargot, are sometimes considered to be "shellfish" and sometimes not.
On occasion, the word is used to refer only to edible marine molluscs, and then shrimp, crab, or lobster are not included in the category. [ [http://textonly.mde.state.md.us/CitizensInfoCenter/FishandShellfish/harvesting_notices/index.asp Maryland Shellfish Harvesting Areas] , Maryland Department of the Environment]
Shellfish are among the most common food allergens.  Some interpretations of
Islamic dietary lawsforbid eating shellfish.
Seventh-day Adventists do not eat shellfish.A rational basis is the tendency of some shellfish to feed on waste or accumulate toxins or heavy metals in their tissues, or that some of these dishes are consumed raw and spoiled shellfish have the potential to cause
shellfish poisoning, and that some people suffer from allergies to shellfish.
* [http://www.bbc.co.uk/food/back_to_basics/shellfish.shtml BBC Guide to Preparing and Eating Shellfish]
* [http://www.cefas.co.uk/Publications/shellfishnews/default.htm Shellfish News]
* [http://www.hsrl.rutgers.edu/ Haskin Shellfish Research Laboratory] at Rutgers University
* [http://www.shellfish.org.uk/shellfish_gallery.htm Shellfish Gallery] from the
Shellfish Association of Great Britain (SAGB)
* [http://www.ocean.udel.edu/MAS/seafood/shellfish.html Shellfish Facts]
*University of Washington Libraries Digital Collections -- [http://content.lib.washington.edu/cgi-bin/queryresults.exe?CISOOP=adv&CISORESTMP=%2Fsite-templates%2Fsearch_results-sub.html&CISOVIEWTMP=%2Fsite-templates%2Fitem_viewer.html&CISOMODE=thumb&CISOGRID=thumbnail%2CA%2C1%3Btitle%2CA%2C1%3Bsubjec%2CA%2C0%3Bdescri%2C200%2C0%3B0%2CA%2C0%3B10&CISOBIB=title%2CA%2C1%2CN%3Bsubjec%2CA%2C0%2CN%3Bdescri%2CK%2C0%2CN%3B0%2CA%2C0%2CN%3B0%2CA%2C0%2CN%3B10&CISOTHUMB=3%2C5&CISOTITLE=10&CISOPARM=%2Ffishimages%3Asubjec%3Ashellfish&x=25&y=6 Freshwater and Marine Image Bank -- Shellfish] An ongoing digital collection of images related to shellfish.
* [http://www.healthaliciousness.com/nutritionfacts/nutrition-comparison.php?o=90240&t=15169&h=15159&s=100&e=100&r=100 Nutrition Facts for Various Shellfish]
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