Atlantic Calico Scallop (also known as the Calico Scallop)
Kingdom: Animalia, Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (single valve shown, fan-shaped pectinid)
Species
Argopecten gibbus (Confidence level: High)
Shell Type
Bivalve (single valve shown, fan-shaped pectinid)
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 1.75 inches (38-45 mm) in height, based on comparison with human fingers in hand. Adults typically measure between 1 and 3 inches.
Color & Pattern
Mottled pattern featuring patches of purplish-red, maroon, grey, and off-white set against a pale background. Exterior shows moderate sun-bleaching and beach wear, with fine concentric growth lines crossing prominent radial ribs.
Rarity
Common to Very Common along the southeastern US coast, especially along North Carolina beaches like Oak Island.
Habitat
Subtidal marine environments from shallow waters down to 300 feet (90 meters), preferring sandy, muddy, or gravelly bottoms and eelgrass beds.
Geographic Range
Western Atlantic from North Carolina down through Florida, the Gulf of Mexico, and into the Caribbean Islands.
Description
A classic fan-shaped single valve of an Atlantic Calico Scallop. Features approximately 19-21 strong, rounded radial ribs extending from the umbo to the fluted outer margin. The shell displays characteristic calico mottled coloration with reddish-purple speckling over a greyish-white base.
Key Features
Sub-equal auricles ('ears') at the hinge line, approximately 19-21 rounded radial ribs, and distinct calico-like blotchy mottling on the exterior surface.
Collector Value
Low monetary value ($1 - $5) due to its abundance, but highly cherished by beachcombers for its beautiful variation in colors and patterns.
Condition Notes
Fair to Good beach-found condition. The valve is complete without major chips or cracks, though the surface shows typical surf erosion, slight color fading from sun exposure, and minor marine encrustation near the hinge.
Interesting Facts
Calico scallops have dozens of tiny, bright blue eyes situated along the edge of their mantle that can detect motion and shadow. Unlike many stationary bivalves, they can swim through the water column by rapidly clapping their valves together.
Ecological Role
Serves as an important filter feeder, clearing plankton and particulate matter from the water column, while providing a food source for starfish, gulls, rays, and predatory marine gastropods.
Similar Species
Bay Scallop (Argopecten irradians), which usually has less colorful exterior mottling and deeper grayish-brown tones, and Rough Scallop (Aequipecten muscosus), which features small spinous scales on its ribs.
Beach Finding Tips
Look along the wrack line at low tide following winter storms or strong offshore winds on North Carolina barrier islands like Oak Island and Holdens Beach.
Notes
Oak Island NC