Scallop

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Scallop
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Ostreoida
Suborder: Pectinina
Superfamily: Pectinoidea
Family: Pectinidae
Rafinesque, 1815
Genera

See Pectinidae

A scallop is a marine bivalve mollusc of the family Pectinidae. Scallops live in all of the world's oceans. They have a good reputation as a food source.[1] As bivalves they have two shells. The lower shell is usually white (about 95% of scallops have white lower shells). It can also be orange (4%) or Lemon Yellow (1%).[1] Shell collectors often collect the coloured fan-shaped shells.[1]

The name "scallop" comes from the Old French escalope, which means "shell".[2] Their shells can be up to 15 centimetres (6 inches) wide.[3]

There are more than 300 types of scallop.[3]

Description[change | change source]

Scallops have over 100 blue eyes

Scallops have a central adductor muscle.[4] This is the same as true oysters (family Ostreidae). The inside of their shell has a scar in the middle.[4] This shows where this muscle attaches to the shell.[4] The adductor muscle of scallops is larger and more developed than the adductor muscle of oysters. This is because they swim a lot. Some fishermen and scientists think that scallops migrate.[5] However, there is not much evidence to support this.[5] Their shell shape is quite regular. It is an archetypal form of a seashell. The scallop shell is a common decorative motif.

Scallops have over 100 blue eyes.[3] It is common for them to grow more, so the number changes often.[3] When they are injured, scallops can grow their eyes again.[3] When they lose all their eyes, scallops can grow them back within two months.[3] The eyes are around the edges of their mantles. They are reflector eyes, about one millimetre in diameter. Their retinae are more complex than other bivalves' retinae. Their eyes have two retina types.[3] One responds to light and the other responds to darkness, such as the shadow of a close predator. They cannot resolve shapes. However, they can see patterns of light and motion that change.[6][7]

Reflector eyes are similar to a lens. It is as if mirrors formed the inside of the eye. These mirrors then reflect the image to focus at a central point.[8] This means, if someone looked into the pupil of one of these eyes, he would see the same image that the organism would see.[8] The scallop Pecten has up to 100 millimetre-scale reflector eyes on the edge of its shell. It detects moving objects when they pass each lens.[8]

Food and digestion[change | change source]

Most scallops are filter feeders.[3] They eat plankton.[3] The plankton sometimes has scallop larvae in it. Siphons bring water over a filtering structure. Mucus then traps the food. Next, the cilia on the structure moves the food to the mouth. Then, the scallop digests the food in the stomach and digestive gland. Waste goes through the intestine and exits through the anus.

Life habits[change | change source]

Most scallops live freely.[3] However, some species attach to a substrate by a structure called a byssus.[3] Some cement to their substrate as adults (such as the Hinnites Giganteus).[3] Other scallops can extend a "foot" from their shell.[3] When they contract the foot, they can go deeper into the sand. A free-living scallop swims by opening and closing its shell very fast. The scallop can defend itself in this way. It protects the scallop from threatening predators. "Singing Scallops" can make a small popping sound when they open and close their shells underwater.[9]

Life cycle[change | change source]

Some scallops, such as the Atlantic bay scallop Argopecten irradians do not live for a long time. Others can live 20 years or more.[3] One can estimate their age from the annuli, the concentric rings on their shells.[10]

The scallop family is unusual because of the variety in arrangements for sexual reproduction. In some members of the family, one scallop has only one sex. They are either male or female. However others are simultaneous hermaphrodites so a single scallop has both male and female reproductive organs at the same time.[3][11] A few scallops even change sexes. They are male when they are young and they become female when they grow older.[11]

Red roe comes from female scallops. White roe comes from males. Scallops release Spermatozoa and ova freely into the water during the mating season. Fertilized ova sink to the bottom.[3] The immature scallop hatches after a few weeks. The larvae drift in the plankton until they go to the bottom again to grow. They usually attach by means of byssal threads.

Seafood industry[change | change source]

Wild fisheries and aquaculture[change | change source]

The largest wild scallop fishery is for the Atlantic sea scallop (Placopecten magellanicus) off northeastern United States and eastern Canada. Most of the rest of the world's production of scallops is from Japan (wild, enhanced, and aquaculture), and China (mostly cultured Atlantic bay scallops).[12] In 2005, China accounted for 80% of the global scallop and pecten catch, according to a Food and Agriculture Organization (FAO) study.[13]

Scallops are most often harvested using scallop dredges or bottom trawls.[14] Recently, fishmongers have started selling scallops harvested by divers.[15] They catch them by hand on the ocean floor.[15] They are often less gritty than scallops collected by dredges. They may also be more ecologically friendly.[15] This is because the harvesting method does not damage the undersea plants or animals.[15] Also, dredge-harvesting methods sometimes delay the arrival of the scallops at the market. This can cause the flesh to deteriorate, and it results in a much shorter shelf life.

Sustainability[change | change source]

New Zealand

In New Zealand numbers of scallops have fallen.[16] Therefore the Tasman Bay area has been closed to commercial scallop harvesting for the past two years.[16][17] Scientists are conducting research funded by the industry to study harvesting patterns. Forest and Bird list scallops as "Worst Choice" in their Best Fish Guide for sustainable seafood species.[18]

United States

Over the last 100 years, on the east coast of the United States, the numbers of bay scallops have fallen a lot.[1] This is because of several things. The main factor is the reduction in sea grasses because of the development on the coast.[1] Bay scallop spat attach to these grasses. Another possible factor is the reduction of shark numbers.[19] They are often fished too much. This variety of shark feeds on rays. Rays are the main predator of bay scallops.[19] With fewer sharks, rays can freely eat scallops. This is greatly decreasing their numbers.[19] By contrast, the Atlantic sea scallop is very abundant after recovery from overfishing.[20]

As food[change | change source]

Scallops are popular in both Eastern and Western cooking. They have two types of meat in one shell. The adductor muscle is white and meaty.[21] The roe, called "coral", is red, orange or white and soft.[21]

In Western cuisine, scallops are often sautéed in butter, or breaded and deep fried.[22] The byssus (also called the beard)[23] is often tough. It is usually discarded or used later on for stock.[24] Sometimes, markets sell scallops already prepared in the shell, with only the adductor muscle.[25] Outside the U.S. the scallop is often sold whole, and people eat the adductor muscle and roe.[25]

"Dry packed" scallops have no additives in them.[26] "Wet packed" scallops have sodium tripolyphosphate (STPP) put in them.[26] STPP makes the scallops absorb moisture before the freezing process.[26] This way, fishermen get a better price per unit of weight.

In Japanese cuisine, scallops may be served in soup or prepared as sashimi or sushi.

In a sushi bar, hotategai (帆立貝, 海扇) is the traditional scallop on rice.[27] Kaibashira (貝柱) might be scallop, but it can also be the adductor muscle of any kind of shellfish, such as mussels, oysters, or clams.[28] In Cantonese Chinese cuisine dried scallop is called conpoy (乾瑤柱, 乾貝, 干貝).

Scallops have given their name to the culinary term scalloped. It originally referred to seafood creamed and served hot in the shell.[29] Today it means a creamed casserole dish such as scalloped potatoes, which contains no seafood at all.[30]

Symbolism[change | change source]

A pilgrim with a scallop shell

Shell of Saint James[change | change source]

The scallop shell is the traditional emblem of James, son of Zebedee.[9] It is popular with pilgrims on the Way of St James to the apostle's shrine at Santiago de Compostela in Spain. Medieval Christians making the pilgrimage to his shrine often wore a scallop shell symbol on their hat or clothes.[9] The pilgrim also carried a scallop shell with him.[9] He would go to churches, castles, abbeys, etc. Here he would get as much food as he could pick up with the shell.[9] He would probably get oats or barley to eat, and maybe beer or wine to drink. This way, even the poorest household could give charity without it being too expensive for them. Saint James' association with the scallop probably comes from a legend. This legend says that the apostle once rescued a knight covered in scallops.[31]

Fertility symbol[change | change source]

Aphrodite in a sea shell, now in the Louvre

Throughout antiquity, scallops and other hinged shells have symbolized the feminine principle (the feminine aspect of God).[32]

Many paintings of Venus, the Roman goddess of love and fertility, have a scallop shell in the painting to identify her.[14] For example, Botticelli's painted one in The Birth of Venus (also known as Venus on the half-shell).[33]

One legend of the Way of St. James says that the route is a kind of fertility pilgrimage. It could be made when a young couple desire to have children. Historians believe the pagans first used the scallop shell as a symbol of fertility.[34][35]

Heraldry[change | change source]

A scallop shell as a heraldic device on a German coat of arms

Heraldry included the scallop shell symbol as a badge for people who had made the pilgrimage to Compostela.[36] Later it became a symbol of pilgrimage in general. Winston Churchill's family coat of arms includes scallops.[37] However, symbols in heraldry do not always have the same meaning. Sometimes no family member has been on a pilgrimage but there are still scallops on the coat of arms.

Over 45 communes of France have one or more scallop shells on their coat of arms.[38]

Other uses[change | change source]

The U.S. state of New York has had the Atlantic bay scallop as its state shell since 1988.[39] In design, scalloped edges or ridges means a wavy pattern which reminds people of the edge of a scallop's shell.[30] Shell petroleum company has had a logo with a scallop shell on it since 1904.[40]

References[change | change source]

  1. 1.0 1.1 1.2 1.3 1.4 FSU Coastal & Marine Laboratory. "Article about Scallops". http://www.marinelab.fsu.edu/faculty/scallop.html. Retrieved 2011-08-15.
  2. "Origin of the word "Scallop"". http://www.etymonline.com/index.php?term=scallop. Retrieved 2011-08-14.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 Burton, Maurice; Robert Burton (2002). International Wildlife Encyclopedia. Marshall Cavendish Corporation. pp. 2248-2249. ISBN 978-0761472827. http://books.google.com/books?id=4QQCfJnu_6oC&pg=PA2249&dq=scallop+eyes&hl=en&ei=a0JJTqL4OY6d-wbnreSZBw&sa=X&oi=book_result&ct=result&resnum=2&ved=0CC4Q6AEwAQ#v=onepage&q=scallop%20eyes&f=false. Retrieved 2011-08-15.
  4. 4.0 4.1 4.2 National Museum Wales, Department of Biodiversity & Systematic Biology. "Bivalve Shell Structures". http://naturalhistory.museumwales.ac.uk/britishbivalves/Morphology.php. Retrieved 2011-08-15.
  5. 5.0 5.1 Scallops: Biology, Ecology and Aquaculture, Volume 35, Second Edition (Developments in Aquaculture and Fisheries Science). Elsevier Science. 2006. pp. 709. ISBN 978-0444504821. http://books.google.com/books?id=1qvoa2ULLD4C&pg=PA709&lpg=PA709&dq=scallop+migrate&source=bl&ots=BfK9x9e5HU&sig=4F4XsjPcrDRjcQR5XZZip0v-dGY&hl=en&ei=ejZJTqGrLcfbsgbOz4GsAg&sa=X&oi=book_result&ct=result&resnum=5&ved=0CDQQ6AEwBA#v=onepage&q=scallop%20migrate&f=false. Retrieved 2011-08-15.
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  7. Land MF and Fernald RD (1992) "The evolution of eyes" Annual review of neuroscience, 15: 1–29.
  8. 8.0 8.1 8.2 Land, M F; Fernald, R D (1992). "The Evolution of Eyes". Annual Review of Neuroscience 15: 1–29. doi:10.1146/annurev.ne.15.030192.000245. PMID 1575438.
  9. 9.0 9.1 9.2 9.3 9.4 Le Cordon Bleu Cuisine Foundations. Delmar Cengage Learning. 2010. pp. 300. ISBN 978-1435481374. http://books.google.com/books?id=8Wf-NFH5ZuoC&pg=PA300&dq=scallop+singing&hl=en&ei=wlBJTqnOCoij-gaOzY2UDg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CC8Q6AEwAQ#v=onepage&q=scallop%20singing&f=false. Retrieved 2011-08-15.
  10. Journal of the Fisheries Research Board of Canada. Canada: University of Toronto Press. 1971. pp. 1335-1337. http://books.google.com/books?ei=Kk5JTrneNc6A-waHpKzXCw&ct=result&id=vUkqAQAAIAAJ&dq=scallop+annuli&q=annuli#search_anchor. Retrieved 2011-08-15.
  11. 11.0 11.1 Jennings, Simon; Michel J. Kaiser, John D. Reynolds (2001). Marine fisheries ecology. Wiley-Blackwell. pp. 56. ISBN 978-0632050987. http://books.google.com/books?id=oTVyeNQyoiMC&pg=PA56&dq=dioecious+hermaphrodite+scallop&hl=en&ei=-kxJTtK8Nsqd-wasmLS3Dg&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q&f=false. Retrieved 2011-08-15.
  12. "Production of scallops". http://docs.google.com/viewer?a=v&q=cache:7KhmKJf7AKAJ:www.montereybayaquarium.org/cr/cr_seafoodwatch/content/media/MBA_SeafoodWatch_FarmedScallopsReport.pdf+scallops+production+china&hl=en&pid=bl&srcid=ADGEEShG-SJOa_C98I8NoZFkFzA0ObQjDu60q7PmsLL_70CeVyAGP8pxEO0t0t-inWbiSb20Jf1jwnguWi3tAqE2dBTDWkVSAVCq4C08iaVYL3PLyKljcv1uQfkeHmHn5rPFXqD-3k6q&sig=AHIEtbTwg06207ffZoDRX64CfGk0sG5Ktg. Retrieved 2011-08-15.
  13. "China catches 1m tonnes of scallops and pectens in 2005". http://www.fao.org/figis/servlet/SQServlet?file=/usr/local/tomcat/FI/5.5.23/figis/webapps/figis/temp/hqp_30407.xml&outtype=html. Retrieved 2011-08-14.
  14. 14.0 14.1 "Scallop facts". http://seagrant.gso.uri.edu/factsheets/scallop.html. Retrieved 2011-08-15.
  15. 15.0 15.1 15.2 15.3 "Harvesting of Scallops". http://findarticles.com/p/articles/mi_m0FDG/is_4_103/ai_n15893509/. Retrieved 2011-08-15.
  16. 16.0 16.1 Arnold, Naomi (2010-01-20). "Tasman Bay Mystery". New Zealand: The Nelson Mail. http://www.stuff.co.nz/nelson-mail/3246181/Dora-to-explore-Tasman-Bays-depths. Retrieved 2011-08-15.
  17. "Tasman Bay closed to Fishermen". http://www.landcareresearch.co.nz/publications/casestudies/case_details.asp?Highlight_ID=7. Retrieved 2011-08-15.
  18. "Forest and Bird Best Fish Guide for sustainable seafood species". http://www.forestandbird.org.nz/what-we-do/publications/-best-fish-guide-/scallops. Retrieved 2011-08-14.
  19. 19.0 19.1 19.2 Trophic Cascades: Predators, Prey, and the Changing Dynamics of Nature. Island Press. 2010. pp. 42-45. ISBN 978-1597264877. http://books.google.com/books?id=tjOT8KJ6mF8C&pg=PA44&dq=scallop+ray&hl=en&ei=o1NJTqLyMoaM-wbi34SYBw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CDcQ6AEwAw#v=onepage&q=scallop%20ray&f=false. Retrieved 2011-08-15.
  20. Proceedings of the North Pacific Aquaculture Symposium. Alaska, USA: Alaska Sea Grant College Program, University of Alaska. 1982. pp. 301. http://books.google.com/books?ei=-lRJTvfbC4X0-gbNnPGEBw&ct=result&id=yFARAAAAYAAJ&dq=scallop+atlantic+sea+abundant&q=abundant+scallop#search_anchor. Retrieved 2011-08-15.
  21. 21.0 21.1 "Dive Planet NZ recipe". http://www.diveplanet.co.nz/RECIPES/SHELLFISH+RECIPES/Scallop+Fettuccine.html. Retrieved 2011-08-15.
  22. Livingston, A.D. (1998). Shellfish Cookbook. Stackpole Books. pp. 158-168. ISBN 978-0811729239.
  23. "Other name of the byssus". http://www.epicurious.com/tools/fooddictionary/search?query=beard. Retrieved 2011-08-14.
  24. Larousse Gastronomique, Clarkson Potter/Publishers, 2001, p. 1062
  25. 25.0 25.1 "Delia's page about scallops". http://www.deliaonline.com/ingredients/ingredients-a-z/ingredients-s-u/Scallops.html. Retrieved 2011-08-15.
  26. 26.0 26.1 26.2 "About dry packed and wet packed scallops". http://www.cookthink.com/reference/708/What_are_dry-packed_scallops. Retrieved 2011-08-15.
  27. "A to Z of Sushi". http://www.sushisushi.co.uk/store/gbu0-display/atoz_h.html. Retrieved 2011-08-15.
  28. "Sushi terminology". http://www.sushifaq.com/terminology.htm. Retrieved 2011-08-15.
  29. Rombauer, Irma (1964). Joy of Cooking. The Bobbs Merrill Company.
  30. 30.0 30.1 "Definition of scalloped". http://www.thefreedictionary.com/scalloped. Retrieved 2011-08-15.
  31. "About Saint James". http://www.spanish-fiestas.com/spanish-festivals/feast-of-saint-james.htm. Retrieved 2011-08-15.
  32. Salisbury JE (2001) Women in the ancient world, p. 11. ABC-CLIO, ISBN 9781576070925.
  33. Porter D and Prince D (2009) Frommer's Italy 2010, p. 273. Frommer's, ISBN 9780470470695.
  34. Slavin S (2003) "Walking as Spiritual Practice: The Pilgrimage to Santiago de Compostela" Body and Society 9(1):18. doi 10.1177/1357034X030093001
  35. Gauding M (2009) The Signs and Symbols Bible: The Definitive Guide to Mysterious Markings, Page 169. Sterling Publishing Company. ISBN 9781402770043
  36. Resurgence, Issue 146. The University of Michigan. 1991. pp. 24.
  37. "Churchill Coat of Arms". http://www.winstonchurchill.org/learn/reference/armorial-bearings-of-wsc. Retrieved 2011-08-15.
  38. "Scallop shells on coats of arms in France". http://www.saint-jacques.info/dechiffrer/blasons.html. Retrieved 2011-08-14. (French)
  39. "New York State emblems". http://www.nysl.nysed.gov/reference/emblems.htm. Retrieved 2011-08-15.
  40. "R.D. Shell Logo". http://www.shell.co.uk/home/content/gbr/aboutshell/who_we_are_tpkg/our_history/history_logo/. Retrieved 2011-08-19.

Further reading[change | change source]

  • Barucca M, Olmo E, Schiaparelli S, Canapa A (2004) Molecular phylogeny of the family Pectinidae (Mollusca: Bivalvia)
  • Rombauer, Irma S. and Marion Rombauer Becker (1931 [1964]) The Joy of Cooking, p 369. Indianapolis: Bobbs-Merrill. ISBN 0-452-25665-8.

Other websites[change | change source]