''Argopecten gibbus'', the Atlantic calico scallop, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of medium-sized edible marine

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family

Pectinidae Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...

, the scallops. This species was once the basis of an important fishery, but in recent years catches have been low.Atlantic calico scallop in Smithsonian museum
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Description

This species grows up to three inches in maximum width, and is similar in shape and sculpturing to the

Atlantic bay scallop ''Argopecten irradians'', formerly classified as ''Aequipecten irradians'', common names Atlantic bay scallop or bay scallop, is a species of scallop in the family Pectinidae. An edible saltwater clam, it is native to the northwest Atlantic fr ...

. Both valves of the shell are cupped. The shell near the hinge is extended into "ears", as is the case in all scallops. The shell of the Atlantic calico scallop has about 20 radial ribs, which are sometimes roughened by growth lines. The exterior coloration of the upper (left) valve of this species is most typically a mottled pattern of purple on a cream background. The lower (right) valve of this scallop is usually whitish with small reddish or purple spotting on the sides. The interior of the shell is white, often with some beige coloration on the "ears" and top edge. The eye-catching color of the shell of this species gave rise to its popular name; in the US, "calico" was for many years an inexpensive but colorful fabric printed with small flower patterns. The name is no longer in practice within the US.

Habitat

The Atlantic calico scallop ranges from

Delaware Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, and is still sometimes fished commercially. It is not found in bays; instead it lives in open water up to 100-foot depths. The shells are commonly found washed up on ocean beaches. Valve color and shell morphometry distinguish calico scallops from related species. In the

Indian River Lagoon The Indian River Lagoon is a grouping of three lagoons: the Mosquito Lagoon, the Banana River, and the Indian River, on the Atlantic Coast of Florida; one of the most biodiverse estuaries in the Northern Hemisphere and is home to more than 4,30 ...

in Florida, two other scallops occur: the bay scallop, ''( Argopecten irradians''), which generally has a uniform gray to gray-brown coloration with distinct convexity of the right (lower) valve. The other is the rough scallop, (''Aequipecten muscosus''), which has unequal 'ears' and has sharp scales on the lower surface of the ribs. The color of the rough scallop is yellow, orange, red or brownish.

References

The superfamily Pectinacea and scallops
*
North Calorina Sea Grant

External links

The Evolution of the Argopecten gibbus Stock (Mollusca: Bivalvia), with Emphasis on the Tertiary and Quaternary Species of Eastern North America
{{Taxonbar, from=Q3017111 gibbus Molluscs described in 1767 Taxa named by Carl Linnaeus