Calico Scallop (also known as the Atlantic Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole shell, fan-shaped
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped
Family
Pectinidae (Scallop family)
Size
Approximately 1 to 1.5 inches, which is average for this species. Adults typically range between 1 and 2 inches in diameter.
Color & Pattern
Pale whitish or off-white base color with faint, faded pinkish mottling and hints of brownish patches. The colors appear slightly sun-bleached. The interior is partially obscured but typically white with a dark purple or brown hinge scar.
Rarity
Very Common, frequently encountered washed up on beaches throughout its native range, especially along the southeastern United States and Florida coastlines.
Habitat
Found in shallow marine waters, typically inhabiting sandy or shelly substrates in marine environments, often associated with seagrass beds from the intertidal zone down to depths of about 150 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina south through Florida, the Gulf of Mexico, and the Caribbean Sea.
Description
A charming, small, fan-shaped bivalve shell with numerous well-defined, rounded radial ribs radiating from the umbo to the ventral margin. The margins are slightly wavy, matching the exterior ribbing. A prominent circular predatory bore hole is visible near the top center of the valve.
Key Features
Symmetric, fan-shaped bivalve morphology, equal-sized auricles (ears) at the hinge, pronounced and uniform radial ribs numbering around 18-22, and a convex rounded profile.
Collector Value
Low to moderate value. Because calico scallops are extremely abundant, individual beach-worn specimens hold little monetary value (under $1), though matching pairs or live-taken gem specimens in vibrant color morphs are popular in shell crafts and beginner collections.
Condition Notes
Fair condition. The shell is intact and retains its basic structural form and ribbing, but it is somewhat sun-bleached and worn. Notably, it features a distinct predatory drill hole near the umbo, likely made by a carnivorous sea snail such as a murex or whelk. Collectibility grade: Fair.
Interesting Facts
Scallops are among the few bivalves that can swim actively by rapidly clapping their valves together to expel water, creating jet propulsion. They also possess dozens of simple blue eyes along the mantle edge that can detect light and shadow.
Ecological Role
Calico scallops serve as an important food source for numerous marine predators including fish, crabs, rays, and sea turtles. They are filter feeders, helping to clear suspended organic matter from the water column.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to be slightly larger with fewer, flatter ribs and a more northern distribution.
Beach Finding Tips
Look along high-tide wrack lines on sandy ocean-facing beaches in Florida and the Carolinas, particularly after storms or heavy winds. Low tide offers the best hunting ground.