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 shells, fan-shaped disc
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shells, fan-shaped disc
Family
Pectinidae (Scallop family)
Size
Approximately 1 to 1.5 inches in diameter, which is typical for this species. Adults generally range from 1 to 2 inches.
Color & Pattern
Highly variable mottled or zigzag patterns of reddish-brown, orange, purple, and yellow on a whitish or cream background, creating a calico fabric-like appearance. Colors are natural and bright. The interior is often white with a dark purple blotch near the hinge.
Rarity
Common to Very Common, frequently found washed ashore in large numbers along southeastern US and Gulf Coast beaches.
Habitat
Shallow subtidal waters to moderate depths, typically found on sandy bottoms, shell gravel, and seagrass beds in marine environments.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, the Caribbean, and south to Brazil.
Description
These small, attractive bivalves feature roughly symmetrical, rounded fan-shaped discs with distinctive radiating ribs (usually 18 to 21 ribs). The ears (auricles) at the hinge are somewhat unequal in size. The exterior displays a delightful mottled pattern resembling calico cloth, while the margins are finely scalloped and interlocking.
Key Features
Rounded, nearly equilateral fan shape with 18-21 prominent, rounded radial ribs, unequal auricles at the hinge, and characteristic colorful calico mottling.
Collector Value
Low to moderate commercial and collector value due to abundance, though well-matched pairs or unusual color morphs are popular in shell craft and starter collections, valued at a few cents to a dollar per specimen.
Condition Notes
The shells appear to be in good to fine collection condition, mostly intact single valves or matched pairs, displaying vivid natural coloration with minimal wear or bleaching.
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 sea stars.
Ecological Role
Calico scallops serve as an important food source for numerous marine predators including fish, rays, sea turtles, and octopuses. They are filter feeders that help maintain water quality.
Similar Species
Bay Scallop (Argopecten irradians), which tends to be slightly larger with flatter ribs and is typically found in shallower grass flats rather than deeper offshore waters.
Beach Finding Tips
Look along high tide lines on Gulf Coast and Florida beaches after stormy weather or strong offshore winds, particularly where commercial shrimping or dredging discards shell debris.