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{{Taxobox
| name = Pectinoidea<br />Pectinidae
| image = Annachlamys flabellata 003.jpg
| image_width = 250px
| regnum = [[Animal]]ia
| phylum = [[Mollusk|Mollusca]]
| classis = [[Bivalvia]]
| ordo = [[Ostreoida]]
| subordo = [[Pectinina]]
| superfamilia = '''Pectinoidea'''
| familia = '''Pectinidae'''
| familia_authority = [[Rafinesque]], 1815
}}
[[File:Argopecten irradians.jpg|thumb|right|250px|''Argopecten irradians'', the Atlantic Bay scallop]]
[[File:Scallop eyes2.jpg|thumb|250px|Macro photo of a scallop showing some of its 110+ bright blue eyes]]

A '''scallop''' is a [[Ocean|marine]] [[bivalve]] [[mollusc]] of the [[Family (biology)|family]] '''Pectinidae'''. Scallops live in all the [[World Ocean|world's oceans]].

This is one of the largest families of living bivalves. There are over 300 living species of scallop.<ref name=IWE/> Their main [[adaptation]] is the ability to [[swim]] by clapping their valves together. In this way they escape from most of their [[predators]].<ref name=Morton>Morton J.E. 1964. ''Molluscs''. 3rd ed, London: Hutchinson, p55.</ref>

They have a good [[reputation]] as a [[food]] source.<ref name=Marine_Lab/> As bivalves they have one hinged shell; each half is known as a valve. The lower valve is usually white (about 95[[Percent|%]]). It can also be [[Orange (color)|orange]] (4%) or [[Yellow|Lemon Yellow]] (1%).<ref name=Marine_Lab>{{cite web|url=http://www.marinelab.fsu.edu/faculty/scallop.html|title=Article about Scallops|author=FSU Coastal & Marine Laboratory|accessdate=2011-08-15|archive-date=2011-07-13|archive-url=https://web.archive.org/web/20110713090438/http://www.marinelab.fsu.edu/faculty/scallop.html|url-status=dead}}</ref>

The name "scallop" comes from the [[Old French]] ''escalope'', which means "shell".<ref>{{cite web|url=http://www.etymonline.com/index.php?term=scallop|title=Origin of the word "Scallop"|accessdate=2011-08-14}}</ref> Their shells can be up to 15 [[centimetre]]s (6 [[inches]]) across.<ref name=IWE/>

== Main features ==
1. Their ability to swim.<ref name=Morton/> However, a few species attach to rocks as adults by a filament. Most species lie on sandy beds, and swim off when touched by a [[starfish]] or other predator.

2. They have eyes round the edges of their [[mantle (mollusc)|mantle]]. Their eyes cannot see shapes, but they can detect  changing patterns of light and motion.<ref name=IWE>{{cite book |title=International Wildlife Encyclopedia |last=Burton |first=Maurice |author2= Robert Burton |year=2002 |publisher=Marshall Cavendish Corporation |location= |isbn=978-0761472827 |pages=2248–2249 |url=https://books.google.com/books?id=4QQCfJnu_6oC&dq=scallop+eyes&pg=PA2249 |accessdate=2011-08-15 }}</ref>
<ref>[http://www.asknature.org/strategy/1e779a45a88aef5c45448073f1e77216 Eyes detect changing movement patterns: queen scallop - Ask Nature - the Biomimicry Design Portal: biomimetics, architecture, biology, innovation inspired by nature, industria...]</ref><ref name=Land1992>Land M.F. and Fernald R.D. 1992. [http://redwood.berkeley.edu/vs265/landfernald92.pdf The evolution of eyes] {{Webarchive|url=https://web.archive.org/web/20180109063904/http://redwood.berkeley.edu/vs265/landfernald92.pdf |date=2018-01-09 }} ''Annual review of neuroscience,'' '''15''': 1–29.</ref>  The scallop eyes fringing the edge of its shell detect moving objects as they pass successive eyes.

3. Semi-circular ridged shape to the shell. The valves are similar, and fit closely together to make a tight-fitting shell.

4. At some stage in their lives, all scallops all have a ridge of tiny teeth near the notch where the [[byssus]] comes out in other [[bivalves]]. This is called the ''ctenolium''. Its importance is that only scallops have it, and it can be seen in fossils. So that tells palaeontologists when they have a fossil scallop.
[[File:Scallop Diagram2.svg|thumb|550px|center|Anatomical diagram of a typical [[hermaphrodite|hermaphroditic]] scallop with the left (upper) valve removed]]

== Muscles ==
Scallops have a central [[adduction|adductor]] [[muscle]].<ref name=Bivalve/> This is the same as true [[oyster]]s (family [[Ostreidae]]). The inside of their shell has a [[scar]] in the middle.<ref name=Bivalve>{{cite web|url=http://naturalhistory.museumwales.ac.uk/britishbivalves/Morphology.php|title=Bivalve shell structures|author=National Museum Wales, Department of Biodiversity & Systematic Biology|accessdate=2011-08-15}}</ref> This shows where this muscle [[wikt:attach|attaches]] to the shell.<ref name=Bivalve/> The adductor muscle of scallops is larger and more developed than the adductor muscle of oysters. This is because they swim.

== Food and digestion ==
Most scallops are [[filter feeder]]s.<ref name=IWE/> They eat [[plankton]].<ref name=IWE/> The plankton sometimes has scallop [[larvae]] in it. [[Siphon (mollusc)|Siphons]] bring water over a [[filter]]ing structure. [[Mucus]] then [[wikt:trap|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 [[digestion|digestive gland]]. Waste goes through the [[intestine]] and exits through the [[anus]].

== Life cycle ==
Some scallops, such as the Atlantic bay scallop ''Argopecten irradians'' do not live for a long time. Others can live 20 years or more.<ref name=IWE/>
One can [[Estimation|estimate]] their [[Ageing|age]] from the [[annulus (zoology)|annuli]], the [[concentric]] [[circle|ring]]s on their shells.<ref>{{cite book |title=Journal of the Fisheries Research Board of Canada |author= Fisheries Research Board of Canada, Biological Board of Canada |year=1971 |publisher=University of Toronto Press |location=Canada |isbn= |pages=1335–1337 |url=https://books.google.com/books?id=vUkqAQAAIAAJ&q=annuli |accessdate=2011-08-15}}</ref>

The scallop family is unusual because of the variety in arrangements for [[sexual reproduction]]. In some species, a scallop has only one sex. They are either male or female. Other species are [[hermaphrodite]]s so a single scallop has both male and female reproductive organs at the same time.<ref name=IWE/><ref name=MFE>{{cite book |title=Marine fisheries ecology |last=Jennings |first=Simon |author2=Michel J. Kaiser, and John D. Reynolds |year=2001 |publisher=Wiley-Blackwell |location= |isbn=978-0632050987 |pages=56 |url=https://books.google.com/books?id=oTVyeNQyoiMC&dq=dioecious+hermaphrodite+scallop&pg=PA56 |accessdate=2011-08-15}}</ref> A few scallops are male when they are young and they become female when they grow older.<ref name=MFE/>

Red [[roe]] comes from female scallops. White roe comes from males. Scallops release [[Spermatozoa]] and [[Ovum|ova]] freely into the water during the mating season. [[Fertilization|Fertilized]] ova sink to the bottom.<ref name=IWE/> The immature scallop hatches after a few weeks. The larvae drift in the plankton until they go to the bottom again to grow. They may attach by means of [[Byssus|byssal threads]].

== Fossil record ==
There are many Pectinidae species, living and [[fossil]]. True Pectinidae (ones with a ''ctenolium'') first appeared in the [[Upper Triassic|Upper]] or [[Middle Triassic]] over 200 million years ago (mya), and perhaps as early as 240 mya.<ref>''Treatise on invertebrate paleontology''. 1969. Geological Society of America, Kansas, Part N, Vol. I page N348.</ref><ref>Waller T.R. 1993. The evolution of ''Chlamys'' (Mollusca: Bivalvia: Pectinidae) in the tropical western Atlantic and eastern Pacific. American ''Malacological Bulletin'' '''10''' (2): 195-249.</ref>

The Pectinidae family had a large number of species in the [[Mesozoic]] [[era]], but they almost [[extinction|disappeared]] at the end of the [[Cretaceous period]]. The survivors evolved rapidly during the [[Tertiary]] period. There are nearly 7,000 species and subspecies for the fossil and recent Pectinidae.

== Evolution ==
The evolution of bivalves that swim is a consequence of the so-called "[[Mesozoic marine revolution]]".<ref name=Vermeij1977>{{cite journal| author = Vermeij G.J.| date =  1977 | title = The Mesozoic marine revolution; evidence from snails, predators and grazers| journal = Paleobiology| volume = 3| issue = 3 | pages = 245–258| doi = 10.1017/S0094837300005352 | jstor = 2400374 | s2cid = 54742050 | url = https://www.jstor.org/pss/2400374 | accessdate = 2008-05-13}}</ref><ref name=Stanley2008>{{cite journal| author = Stanley S.M.| year = 2008| title = Predation defeats competition on the seafloor| journal = Paleobiology| volume = 34| pages = 1–21| doi = 10.1666/07026.1| s2cid = 83713101}}</ref><ref>{{cite journal|author=Stanley SM |year=1974 |title=What has happened to the articulate brachiopods? |journal=GSA Abstracts with Programs |volume=8|pages=966–967}}</ref> In the [[Mesozoic]] era sea-floor predators evolved various new forms which fed on the abundant shellfish ([[brachiopod]]s and [[bivalves]]). These predators are still abundant today: they are mostly the [[starfish]],<ref>Blake D.B. 1981. The new Jurassic sea star ''Eokainaster'' and comments on life habit and the origins of modern Asteroidea. ''J. Paleont.'' '''55''', 33–46.</ref> the [[gastropods]], and the [[crabs]].

Each predator has its own methods. Crabs break the shells by force. Some gastropods make holes in the shell and put in a [[paralysis|paralysing]] or relaxing substance; others work on small cracks in the edge of the shell. Once they get their [[proboscis]] in, they eat the shellfish.

Starfish are the most common predators. The shells of brachiopods and bivalves are held together by strong muscles. What the starfish does is clamp hold of them on either side with its [[tube feet]], and apply a steady pull. The starfish, with its muscles and [[hydraulic]] system, can pull for much longer than any bivalve muscle can withstand. Apparently, ten minutes are usually enough to open the shell a bit. Then the starfish slips its stomach inside the shell. The stomach can get through a slot as narrow as 0.1mm.<ref>Vermeij G.J. 1987. ''Evolution and escalation: an ecological history of life''. Princeton N.J. p153</ref> The starfish then dissolves the [[mollusc]] where it lives, absorbing the [[nutrient]]s.

Consequently, there was a great reproductive advantage for any prey which had even the slightest defence to these predators. Many shellfish developed extra-tough shells. Some burrowed into the sand. Scallops must had had some elementary movement, which developed rapidly under [[natural selection|selection]].  They became extremely common in the Mesozoic. There are some other methods used by a few scallops. ''[[Chlamys]] hastata'' often carry [[sponge]]s on their shell. It is a kind of [[mutualism]]. The sponge makes it difficult for starfish to get their tube feet on,<ref>{{cite journal|last=Bloom|first=S.|title=The motile escape response of a sessile prey: a sponge-scallop mutualism|journal=Journal of Experimental Biology and Ecology|year=1975|volume=17|issue=3|pages=311–321|url=https://www.researchgate.net/publication/248246332|doi=10.1016/0022-0981(75)90006-4}}</ref><ref>{{cite journal|last=Pitcher|first=C.R.|author2=Butler A.J.|title=Predation by asteroids, escape response, and morphometrics of scallops with epizoic sponges|journal=Journal of Experimental Marine Biology and Ecology|year=1987|volume=112|issue=3|pages=233–249|url=https://dx.doi.org/10.1016/0022-0981%2887%2990071-2|doi=10.1016/0022-0981(87)90071-2}}</ref><ref>{{cite journal|last=Forester|first=A.J.|title=The association between the sponge ''Halichondria panicea'' (Pallas) and scallop ''Chlamys varia'' (L.): a commensal protective mutualism|journal=Journal of Experimental Marine Biology and Ecology|year=1979|volume=36|issue=1|pages=1–10|doi=10.1016/0022-0981(79)90096-0}}</ref> and camouflages ''Chlamys hastata'' from predators.<ref>{{cite journal|last=Pitcher|first=C.R.|author2=Butler, A.J.|title=Predation by asteroids, escape response, and morphometrics of scallops with epizoic sponges|journal=Journal of Experimental Marine Biology and Ecology|year=1987|volume=112|issue=3|pages=233–249|url=https://dx.doi.org/10.1016/0022-0981%2887%2990071-2|doi=10.1016/0022-0981(87)90071-2}}</ref>

When scallops move off the sand they are open to new predators such as [[rays]], which patrol just above the ocean floor. They may also be picked up by seabirds which open shells by dropping them on rock. Evidently the main advantage lies in getting away from the starfish, which are very numerous on [[inshore]] and [[continental shelf]] habitats.

=== Origins ===
Studies have shown the Pectinidae family is [[monophyletic]], developing from a single common ancestor. The direct ancestors of Pectinidae were scallop-like bivalves of the family Entoliidae.<ref>{{cite journal|last=Dijkstra|first=H.H.|author2=Maestrati P.|title=Pectinoidea (Mollusca, Bivalvia, Propeamussiidae, Cyclochlamydidae n. fam., Entoliidae and Pectinidae) from the Vanuatu Archipelago|journal=Zoosystema|year=2012|volume=34|issue=2|pages=389–408|url=http://dare.uva.nl/cgi/arno/show.cgi?fid=454509|doi=10.5252/z2012n2a12|s2cid=85935928}}</ref><ref>{{cite journal|last=Waller|first=T.R.|title=The ctenolium of scallop shells: functional morphology and evolution of a key family-level character in the Pectinacea (Mollusca: Bivalvia)|journal=Malacologia|year=1984|volume=25|issue=1|pages=203–219|url=http://pterioidea.myspecies.info/content/ctenolium-scallop-shells-functional-morphology-and-evolution-key-family-level-character-pect}}</ref>

== As food ==
=== Wild fisheries and aquaculture ===
The largest [[wikt:wild|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, [[wikt:enhance|enhanced]], and [[aquaculture]]), and [[China]] (mostly [[aquaculture|cultured]] Atlantic bay scallops).<ref>{{cite web|url=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|title=Production of scallops|accessdate=2011-08-15}}</ref> In 2005, China accounted for 80[[percent|%]] of the global scallop and pecten catch, according to a [[Food and Agriculture Organization]] (FAO) study.<ref>{{cite web|url=http://www.fao.org/figis/servlet/SQServlet?file=/usr/local/tomcat/FI/5.5.23/figis/webapps/figis/temp/hqp_30407.xml&outtype=html|title=China catches 1m tonnes of scallops and pectens in 2005|accessdate=2011-08-14|archive-date=2011-02-04|archive-url=https://web.archive.org/web/20110204073651/http://www.fao.org/figis/servlet/SQServlet?file=/usr/local/tomcat/FI/5.5.23/figis/webapps/figis/temp/hqp_30407.xml&outtype=html|url-status=dead}}</ref>

=== Cooking ===
Scallops are popular in both Eastern and Western [[cooking]]. They have two types of meat in one shell. The [[adduction|adductor muscle]] is [[white]] and [[wikt:meaty|meaty]].<ref name=DPNZ>{{cite web|url=http://www.diveplanet.co.nz/RECIPES/SHELLFISH+RECIPES/Scallop+Fettuccine.html|title=Dive Planet NZ recipe|accessdate=2011-08-15}}{{Dead link|date=January 2021 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The [[roe]], called "coral", is [[red]], [[orange (colour)|orange]] or white and soft.<ref name=DPNZ/>

In Western [[cuisine]], scallops are often served as an appetizer or starter. Some of the most common ways to cook them are [[Sautéing|sautéed]] in [[butter]] (especially with [[Garlic butter|garlic]]), or [[bread]]ed and [[deep frying|deep fried]].<ref>{{cite book|title=Shellfish Cookbook|last=Livingston|first=A.D.|date=1998|publisher=Stackpole Books|isbn=978-0811729239|pages=158–168}}</ref> They can also be added to [[pasta]],<ref>{{Cite web|last=Sprouts|first=Claire {{!}} Sprinkles and|date=2022-04-27|title=Creamy Scallop Pasta|url=https://www.sprinklesandsprouts.com/creamy-scallop-pasta/|access-date=2023-07-05|website=Sprinkles and Sprouts|language=en-AU}}</ref> and are often served as [[Valentine's Day|Valentine's day]] meals. 

The byssus (also called the beard)<ref>{{cite web|url=http://www.epicurious.com/tools/fooddictionary/search?query=beard|title=Other name of the byssus|accessdate=2011-08-14|archive-date=2012-03-30|archive-url=https://web.archive.org/web/20120330115750/http://www.epicurious.com/tools/fooddictionary/search?query=beard|url-status=dead}}</ref> is often [[wikt:tough|tough]]. It is usually [[waste|discarded]] or used later on for [[stock (food)|stock]].<ref>Larousse Gastronomique, Clarkson Potter/Publishers, 2001, p. 1062</ref> Sometimes, markets sell scallops already prepared in the shell, with only the adductor muscle.<ref name="Delia" /> Outside the U.S. the scallop is often sold whole, and people eat the adductor muscle and roe.<ref name="Delia">{{cite web|url=http://www.deliaonline.com/ingredients/ingredients-a-z/ingredients-s-u/Scallops.html|title=Delia's page about scallops|accessdate=2011-08-15}}</ref>

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.<ref>{{cite web|url=http://www.sushisushi.co.uk/store/gbu0-display/atoz_h.html|title=A to Z of Sushi|accessdate=2011-08-15|archive-date=2009-01-06|archive-url=https://web.archive.org/web/20090106191612/http://www.sushisushi.co.uk/store/gbu0-display/atoz_h.html|url-status=dead}}</ref> ''Kaibashira'' (貝柱) might be scallop, but it can also be the adductor muscle of any kind of shellfish, such as [[mussel]]s, oysters, or [[clam]]s.<ref>{{cite web|url=http://www.sushifaq.com/terminology.htm|title=Sushi terminology|accessdate=2011-08-15}}</ref>
In [[Guangzhou|Cantonese]] [[Chinese cuisine]] dried scallop is called [[conpoy]] (乾瑤柱, 乾貝, 干貝).

<gallery>
File:Large scallops.jpg|Adductor muscle meat of the giant scallop
File:BCfood17.JPG|Taiwanese steamed scallops
File:Scallop-Sausages-DSC2415.jpg|A scallop being grilled next to sausages in Japan
</gallery>

== Symbolism ==
[[File:Carlo Crivelli 064.jpg|thumb|upright|80px|left|A pilgrim with a scallop shell]]
=== Shell of Saint James ===
The scallop shell is the [[tradition]]al [[emblem]] of [[James, son of Zebedee]]. It is popular with [[pilgrims]] on the [[Way of St James]] to the [[Twelve Apostles|apostle]]'s [[shrine]] at [[Santiago de Compostela]] in [[Spain]].

=== Fertility symbol ===
[[File:Aphrodite Anadyomene Louvre CA2288.jpg|thumb|100px|Aphrodite in a sea shell, now in the [[Louvre]]]]

Throughout [[Ancient history|antiquity]], scallops and other [[Bivalvia|hinged shells]] have symbolized the feminine principle.<ref>Salisbury J.E. 2001. ''Women in the ancient world'', p. 11. ABC-CLIO, {{ISBN|9781576070925}}</ref> Many paintings of [[Venus]], the [[Roman mythology|Roman]] [[goddess]] of love and [[fertility]], included a scallop shell in the painting to identify her. This is clear in [[Botticelli]]'s classically inspired ''[[The Birth of Venus]]''

=== Use as a design ===
[[File:Wappen Bad Mingolfsheim.svg|thumb|100px|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.<ref>{{cite book|title=Resurgence, Issue 146|date=1991|publisher=The University of Michigan|pages=24}}</ref> Later it became a symbol of pilgrimage in general. [[Winston Churchill]]'s family [[coat of arms]] includes scallops.<ref>{{cite web|url=http://www.winstonchurchill.org/learn/reference/armorial-bearings-of-wsc|title=Churchill Coat of Arms|accessdate=2011-08-15|archive-date=2013-07-18|archive-url=https://web.archive.org/web/20130718222952/http://www.winstonchurchill.org/learn/reference/armorial-bearings-of-wsc|url-status=dead}}</ref> 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.<ref>{{cite web|url=http://www.saint-jacques.info/dechiffrer/blasons.html|title=Scallop shells on coats of arms in France|accessdate=2011-08-14}} {{in lang|fr}}</ref>

The U.S. state of [[New York]] has had the Atlantic bay scallop as its [[List of U.S. state shells|state shell]] since 1988.<ref>{{cite web|url=http://www.nysl.nysed.gov/reference/emblems.htm|title=New York State emblems|accessdate=2011-08-15}}</ref> In [[design]], ''scalloped edges'' or ''ridges'' means a [[wikt:wavy|wavy]] pattern which reminds people of the edge of a scallop's shell. [[Royal Dutch Shell|Shell]] [[oil|petroleum]] [[company]] has had a logo with a scallop shell on it since 1904.<ref>{{cite web|url=http://www.shell.co.uk/home/content/gbr/aboutshell/who_we_are_tpkg/our_history/history_logo/|title=R.D. Shell Logo|accessdate=2011-08-19|archive-date=2012-06-21|archive-url=https://web.archive.org/web/20120621015555/http://www.shell.co.uk/home/content/gbr/aboutshell/who_we_are_tpkg/our_history/history_logo/|url-status=dead}}</ref>

== References ==
{{Reflist|2}}

=== Further reading ===
* Barucca M. ''et al'' 2004. Molecular phylogeny of the family Pectinidae (Mollusca: Bivalvia)

== Other websites ==
{{wikispecies|Pectinidae}}
{{Spoken article|Simple en Scallop.ogg|2011-08-16}}
* [http://www.mi.nmfs.gov/scallops.html NOAA Fisheries: Northeast Fisheries Science Center] {{Webarchive|url=https://web.archive.org/web/20120726012547/http://www.mi.nmfs.gov/scallops.html |date=2012-07-26 }} - Research on Bay Scallop Aquaculture and Enhancement
* [http://home.planet.nl/~hdykstra/CLASSIFICATION.htm Classification of Pectinoidea] (Propeamussiidae and Pectinidae) - includes partly different genera, with subfamilies and tribes.
* [http://www.sciencenews.org/articles/20070331/fob5.asp "Too Few Jaws: Shark declines let rays overgraze scallops"] {{Webarchive|url=https://web.archive.org/web/20110524101232/http://www.sciencenews.org/articles/20070331/fob5.asp |date=2011-05-24 }}, ''Science News'', March 31, 2007

{{Meat}}

[[Category:Bivalves]]