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 in width, which is average for an adult specimen of this species. Adults typically range from 1 to 2 inches.
Color & Pattern
This particular specimen is pristine white, likely sun-bleached or naturally occurring as an all-white morph. Living specimens typically display vibrant mottled patterns of reddish-brown, purple, orange, or yellow on a white or cream base.
Rarity
Very Common. This is one of the most frequently found whole bivalves on many southeastern United States and Gulf Coast beaches.
Habitat
Found in shallow marine waters, typically ranging from intertidal zones down to depths of about 150 feet. They prefer sandy or shell-gravel substrates and often inhabit seagrass beds.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea.
Description
A classic, symmetrical fan-shaped bivalve with prominent, evenly spaced radial ribs extending from the umbo (beak) to the margin. The margins are scalloped and interlock tightly. The ears (auricles) near the hinge are relatively equal in size.
Key Features
Symmetrical, rounded fan shape, roughly 18-22 prominent radial ribs, and nearly equal auricles (ears) on either side of the beak, distinguishing it from related scallops.
Collector Value
Low to moderate individual value due to abundance, though collectors often seek out unique color morphs or flawless paired valves. Commonly used in shell crafts and sold in tourist shops.
Condition Notes
Gem to Fine condition. The shell appears completely intact with sharp, unchipped margins and well-defined ribs. It is uniformly white, showing minimal wear or marine encrustation.
Interesting Facts
Unlike many bivalves that burrow or cement themselves, Calico Scallops are capable of active swimming. By rapidly clapping their valves together, they expel water and propel themselves through the water column to escape predators.
Ecological Role
Serves as an important prey item for various marine predators including sea stars, fish, octopuses, and gulls. They are filter feeders, helping to clear organic particulate matter from the water column.
Similar Species
Bay Scallop (Argopecten irradians), which tends to be slightly larger with fewer ribs (usually 17 or fewer) and a more flattened profile.
Beach Finding Tips
Best found by beachcombing along high tide wrack lines on Gulf Coast or Florida beaches, especially after storms or winter cold fronts.