Scallop
An edge-on view of a live scallop with the valves open, showing the mantle edges, the small blue pallial eyes and the pallial tentacles
Two scallop valves from Galicia (Spain), showing exterior and interior
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Ostreoida
Suborder:	Pectinina
Superfamily:	Pectinoidea
Family:	Pectinidae Rafinesque, 1815
Genera
See Pectinidae

A scallop (/ˈskɒləp/ or /ˈskæləp/; from Old French escalope, meaning "shell"^[1]) is a common name applied to many species of marine bivalve mollusks in the family Pectinidae, the scallops. Scallops are a cosmopolitan family, found in all of the world's oceans.

Many scallops are highly prized as a food source; the name "scallop" is also applied to the meat of these animals when it is used as seafood. The brightly colored, fan-shaped shells of some scallops, with their radiating fluted pattern, are valued by shell collectors, and have been used since ancient times as motifs in art and design.

Anatomy[edit]

Anatomical diagram of a typical hermaphroditic scallop. The interior of the shell is shown in black only to serve as a contrast.

A live opened scallop showing the internal anatomy. The pale orange circular part is the adductor muscle; the darker orange curved part is the "coral", a seafood name for the ovary.

Muscular system[edit]

Like the true oysters (family Ostreidae), scallops have a central adductor muscle, and thus the inside of their shells has a characteristic central scar, marking the point of attachment for this muscle. The adductor muscle of scallops is larger and more developed than that of oysters, because they are active swimmers; some species of scallops are known to move en masse from one area to another. In scallops the shell shape tends to be highly regular, and is commonly used as an archetypal form of a seashell.

Eyes[edit]

Scallops have up to 100 simple brilliantly blue eyes arranged around the edges of each of their two mantles like strings of beads. They are reflector eyes, about one millimeter in diameter, with a retina that is more complex than those of other bivalves. Their eyes contain two retina types, one responding to light and the other to abrupt darkness, such as the shadow of a nearby predator. They cannot resolve shapes, but can detect changing patterns of light and motion.^[2][3]

Reflector eyes are an alternative to those with a lens, where the inside of the eye is lined with mirrors which reflect the image to focus at a central point.^[4] The nature of these eyes means that if one were to peer into the pupil of an eye, one would see the same image that the organism would see, reflected back out.^[4] The scallop Pecten has up to 100 millimeter-scale reflector eyes fringing the edge of its shell. It detects moving objects as they pass successive eyes.^[4]

Digestive system[edit]

Most scallops are filter feeders, and eat plankton. Incidentally, the plankton can include scallop larvae. They lack siphons. Water moves over a filtering structure, where food becomes trapped in mucus. Next, the cilia on the structure move the food toward the mouth. Then, the food is digested in the digestive gland, an organ sometimes misleadingly referred to as the "liver" but which envelops part of the esophagus, intestine, and the entire stomach. Waste is passed on through the intestine (which, near its terminus, enters and leaves the scallop's heart) and exits via the anus.

Nervous system[edit]

Like all bivalves, scallops lack an actual brain. Instead, the nervous system is controlled by three paired ganglia located at various points throughout its anatomy. These are termed the cerebral ganglia, the pedal ganglia, and the visceral ganglia. All are yellowish in color; the visceral ganglia are by far the largest and most extensive of the three.

Reproduction[edit]

The scallop family is unusual in that some members of the family are dioecious (males and females are separate), while other are simultaneous hermaphrodites (both sexes in the same individual) and a few are protoandrous hermaphrodites (males when young then switching to female). Red roe is that of a female, and white, that of a male. Spermatozoa and ova are released freely into the water during mating season and fertilized ova sink to the bottom. After several weeks, the immature scallop hatches and the larvae, miniature transparent versions of the adults, drift in the plankton until settling to the bottom again to grow, usually attaching by means of byssal threads. Some scallops, such as the Atlantic bay scallop Argopecten irradians, are short lived, while others can live 20 years or more. Age can often be inferred from annuli, the concentric rings of their shells.

Life habits[edit]

Most scallops are free-living, but some species can attach to a substrate by a structure called a byssus, or even be cemented to their substrate as adults (e.g. Hinnites spp.). Other scallops can extend a "foot" from between their valves (shell). By then contracting the foot, they can burrow themselves deeper into sand. A free-living scallop can swim by rapidly opening and closing its shell. This method of locomotion is also a defensive technique, protecting it from threatening predators. So-called Singing Scallops can make an audible soft popping sound as they flap their shells underwater.

Seafood industry[edit]

Wild fisheries[edit]

By far the largest wild scallop fishery is for the Atlantic sea scallop (Placopecten magellanicus) found 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).

Scallops are most commonly harvested using scallop dredges or bottom trawls. Recently, scallops harvested by divers, hand-caught on the ocean floor, have entered the marketplace. In contrast to scallops captured by a dredge across the sea floor, diver scallops tend to be less gritty. They are also more ecologically friendly, as the harvesting method does not cause damage to undersea flora or fauna. In addition, dredge-harvesting methods often result in delays of up to two weeks before the scallops arrive at market^{[citation needed]}, which can cause the flesh to break down, and results in a much shorter shelf life.

Aquaculture[edit]

In 2005, China accounted for 80 percent of the global scallop and pecten catch, according to an FAO study.^[5] Outside of China, Russia remained the industry leader.

Sustainability[edit]

New Zealand[edit]

The Tasman Bay area was closed to commercial scallop harvesting from 2009 to 2011 due to a decline in the numbers. In 2011, industry-funded research was conducted into scallop harvesting patterns. Forest and Bird list scallops as "Worst Choice" in their Best Fish Guide for sustainable seafood species.^[6]

United States[edit]

On the east coast of the United States, over the last 100 years, the populations of bay scallops have greatly diminished. This decrease is due to several factors, but probably is mostly due to reduction in sea grasses (to which bay scallop spat attach) due to increased coastal development and concomitant nutrient runoff. Another possible factor is reduction of sharks from overfishing. A variety of sharks used to feed on rays, which are a main predator of bay scallops. With the shark population reduced — in some places almost eliminated — the rays have been free to dine on scallops to the point of greatly decreasing their numbers. By contrast, the Atlantic sea scallop (Placopecten magellanicus) is at historically high levels of abundance after recovery from overfishing.

As food[edit]

Wikimedia Commons has media related to: Scallop dishes

Scallops are characterized by having two types of meat in one shell: the adductor muscle, called "scallop", which is white and meaty, and the roe, called "coral", which is red or white and soft.

Sometimes, markets sell scallops already prepared in the shell, with only the adductor muscle intact. Outside the U.S. the scallop is often sold whole. In Galician cuisine, scallops are baked with bread crumbs, ham, and onions.

Scallops that are without any additives are called "dry packed", while scallops that are treated with sodium tripolyphosphate (STPP) are called "wet packed". STPP causes the scallops to absorb moisture prior to the freezing process, thereby getting a better price per unit of weight. The freezing process takes about two days.

In Japanese cuisine, scallops may be served in soup or prepared as sashimi or sushi. Dried scallop is known in Cantonese Chinese cuisine as conpoy (乾瑤柱, 乾貝, 干貝).

In a sushi bar, hotategai (帆立貝, 海扇) is the traditional scallop on rice, and while kaibashira (貝柱) may be called scallops, it is actually the adductor muscle of any kind of shellfish, e.g. mussels, oysters, or clams.

Scallops have lent their name to the culinary term scalloped, which originally referred to seafood creamed and served hot in the shell (Rombauer 1964). Today it means a creamed casserole dish such as scalloped potatoes, which contains no seafood at all.

• 

  Adductor muscle meat of the giant scallop

• 

  Dried scallops, also known as conpoy

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  Taiwanese steamed scallops

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  A scallop being grilled next to sausages in Japan

Symbolism[edit]

Portrait by Carlo Crivelli, c. 1480

Shell of Saint James[edit]

The scallop shell is the traditional emblem of James, son of Zebedee, and is popular with pilgrims on the Way of St James to the apostle's shrine at Santiago de Compostela in Galicia (Spain). Medieval Christians making the pilgrimage to his shrine often wore a scallop shell symbol on their hat or clothes. The pilgrim also carried a scallop shell with him, and would present himself at churches, castles, abbeys etc., where he could expect to be given as much sustenance as he could pick up with one scoop. Probably he would be given oats, barley, and perhaps beer or wine. Thus even the poorest household could give charity without being overburdened. The association of Saint James with the scallop can most likely be traced to the legend that the apostle once rescued a knight covered in scallops. An alternative version of the legend holds that while St. James' remains were being transported to Galicia (Spain) from Jerusalem, the horse of a knight fell into the water, and emerged covered in the shells.^{[citation needed]} Indeed, in French the animal (as well as a popular preparation of it in cream sauce) is called Coquille St. Jacques. In German they are "Jakobsmuscheln"—literally "James mussels."

Wikimedia Commons has media related to: Shell of Saint James

Fertility symbol[edit]

Aphrodite in a sea shell, from Amisos, now in the Louvre

Throughout antiquity, scallops and other hinged shells have symbolized the feminine principle.^[7] Outwardly the shell can symbolize the protective and nurturing principle, and inwardly the "life-force slumbering within the Earth",^[8] an emblem of the vulva.^[9][10]

Many paintings of Venus, the Roman goddess of love and fertility, included a scallop shell in the painting to identify her. This is evident in Botticelli's classically inspired The Birth of Venus (also known as Venus on the half-shell^[11]).

One legend of the Way of St. James holds that the route was seen as a sort of fertility pilgrimage, undertaken when a young couple desired to bear offspring. The scallop shell is believed to have originally been carried therefore by pagans as a symbol of fertility.^[12][13]

Alternatively, the scallop resembles the setting sun, which was the focus of the pre-Christian Celtic rituals of the area. To wit, the pre-Christian roots of the Way of St. James was a Celtic death journey westwards towards the setting sun, terminating at the End of the World (Finisterra) on the "Coast of Death" (Costa da Morte) and the "Sea of Darkness" (i.e., the Abyss of Death, the Mare Tenebrosum, Latin for the Atlantic Ocean, itself named after the Dying Civilization of Atlantis).^[14] The reference to St. James rescuing a "knight covered in scallops" is therefore a reference to St. James healing, or resurrecting, a dying (setting sun) knight. Similarly, the notion of the "Sea of Darkness" (Atlantic Ocean) disgorging St. James' body, so that his relics are (allegedly) buried at Santiago de Compostella on the coast, is itself a metaphor for "rising up out of Death", that is, resurrection.^[15]

Heraldry[edit]

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

The scallop shell symbol found its way into heraldry as a badge of those who had been on the pilgrimage to Compostela, although later it became a symbol of pilgrimage in general. Winston Churchill and Diana, Princess of Wales' family, the Spencer family coat of arms includes a scallop, as well as both of Diana's sons Prince William, Duke of Cambridge and Prince Harry of Wales' personal coat of arms; also pope Benedict XVI's personal coat of arms includes a scallop; another example is the surname Wilmot and also John Wesley's (which as a result the scallop shell is used as an emblem of Methodism). However, charges in heraldry do not always have an unvarying symbolic meaning, and there are cases of arms in which no family member went on a pilgrimage and the occurrence of the scallop is simply a pun on the name of the armiger (as in the case of Jacques Coeur), or for other reasons.

Logos used by the Shell Oil Company between 1900 and 1999

State shell of New York[edit]

The state of New York in the United States made the bay scallop (Argopecten irradians) its state shell in 1988.^[16]

Design[edit]

In design, scalloped edges or ridges refers to a wavy pattern reminiscent of the edge of a scallop's shell.

Corporate logo[edit]

The energy corporation Royal Dutch Shell derives its highly recognizable logo from the scallop species pecten maximus.

Britten Memorial[edit]

On the beach at Aldeburgh, Suffolk, England, is Maggie Hambling's metal sculpture, The Scallop, erected in 2003 as a memorial to the composer Benjamin Britten, who had a long association with the town. See Aldeburgh.

References[edit]

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (February 2008)

• 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.

External links[edit]

Look up scallop in Wiktionary, the free dictionary.

Wikispecies has information related to: Pectinidae

• Alaska Department of Fish and Game - scallop page
• NOAA Fisheries: Northeast Fisheries Science Center - Research on Bay Scallop Aquaculture and Enhancement
• Delaware Sea Grant, University of Delaware - scallop page
• Classification of Pectinoidea (Propeamussiidae and Pectinidae) - includes partly different genera, with subfamilies and tribes.
• "Too Few Jaws: Shark declines let rays overgraze scallops", Science News, March 31, 2007

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