Atlantic Calico Scallop (also known as Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole shell, fan shape
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan shape
Family
Pectinidae (Scallop family)
Size
Approximately 1 to 1.5 inches, which is average for this species. Adults typically range from 1 to 2.5 inches.
Color & Pattern
This particular specimen is sun-bleached and worn, presenting a uniform matte white color. In living or fresh specimens, the species typically exhibits a mottled or zig-zag pattern of reddish-brown, orange, purple, or yellow markings on a lighter background, resembling calico cloth.
Rarity
Common (frequently found washed up on beaches throughout its range, though well-preserved colored specimens require more searching).
Habitat
Shallow subtidal marine environments, typically found in sandy areas, seagrass beds, and offshore shoals from the low-tide line down to depths of 160 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea.
Description
A classic bivalve shell featuring a rounded, fan-like morphology with prominent radial ribs radiating outward from the umbo. The margins are scalloped, reflecting the internal ridges of the shell. The surface texture is somewhat chalky due to weathering, lacking its characteristic colorful markings.
Key Features
Nearly equilateral fan shape, prominent and evenly spaced radial ribs (typically around 18 to 22), and slightly unequal auricles (ears) at the hinge line.
Collector Value
Low to moderate collector value. While extremely popular among casual beachcombers and crafters, fully bleached single valves like this are very common and hold little monetary value.
Condition Notes
Fair condition. The shell is structurally intact as a single valve, but it is heavily sun-bleached with a complete loss of original coloration and minor surface wear along the margins.
Interesting Facts
Unlike many bivalves, calico scallops are capable of swimming short distances by rapidly clapping their valves together to expel water, allowing them to escape predators like starfish.
Ecological Role
Scallops serve as an important food source for numerous marine predators including rays, sea stars, crabs, and large fish. They are filter feeders, helping to maintain water clarity.
Similar Species
Bay Scallop (Argopecten irradians), which tends to be slightly larger with fewer and flatter ribs, and the Rough Scallop (Aequipecten muscosus), which has more prominent, scaly ribs.
Beach Finding Tips
Look along high-tide wrack lines on Atlantic and Gulf coast beaches, particularly after storms or heavy onshore winds. Early morning beachcombing often yields the best intact specimens.