Calico Scallop (also known as the Atlantic Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: A. 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 0.75 to 1 inch wide, which is slightly below average for an adult. Adults typically range from 1 to 2.5 inches.
Color & Pattern
Pale off-white or cream base color with faint brownish-pink mottling and radial markings near the umbo. Colors appear somewhat sun-bleached and worn from wave action, typical of a beach-cast specimen.
Rarity
Very Common, frequently found washed up on beaches throughout its range, particularly along the southeastern United States and Gulf Coast.
Habitat
Found in shallow marine waters, primarily in sandy or shell-gravel substrates, often in seagrass beds from the low intertidal zone down to depths of about 150 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through Florida, the Gulf of Mexico, and the Caribbean Sea down to South America.
Description
A small, fan-shaped bivalve with symmetrical or nearly symmetrical ears at the hinge. The exterior features well-defined radial ribs and fine growth lines. The margin is scalloped, and the surface displays a weathered, tumbled appearance typical of beach-worn specimens.
Key Features
Rounded, somewhat inflated fan shape with distinct radial ribs, roughly equal-sized auricles (ears) at the hinge line, and characteristic mottled coloration when fresh.
Collector Value
Low commercial or collector value due to their extreme abundance, though they are very popular among casual beachcombers and used heavily in shell crafts.
Condition Notes
Fair condition. The single valve is intact but shows significant surface weathering, minor edge chipping, and fading of the natural color pattern. Collectibility grade: Fair.
Interesting Facts
Scallops are unique among bivalves because they possess dozens of simple blue eyes along the edge of their mantle, allowing them to detect motion and shadows. They can also swim short distances by rapidly clapping their valves together to expel water.
Ecological Role
Serves as an important prey item for various marine predators including fish, crabs, and sea stars. They filter feed on phytoplankton, helping to maintain water clarity in coastal ecosystems.
Similar Species
Bay Scallop (Argopecten irradians), which tends to be slightly larger with flatter ribs and is typically found in shallower estuarine seagrass beds.
Beach Finding Tips
Look along high-tide lines on sandy beaches in Florida and the Gulf Coast, especially after storms or strong onshore winds.