Atlantic Calico Scallop (also known as 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 disc
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped disc
Family
Pectinidae (Scallop family)
Size
Approximately 1 to 1.5 inches in width, which is average for this species. Adults typically range from 1 to 2.5 inches.
Color & Pattern
Deep reddish-brown to burnt orange base coloration with fine, darker radiating ribs and subtle mottled or checkered patterns reminiscent of calico fabric. Colors appear entirely natural and well-preserved.
Rarity
Common, frequently found washed ashore along southeastern US and Gulf of Mexico beaches after storms or high tides.
Habitat
Found in marine environments in shallow to moderately deep subtidal waters, typically on sandy substrates and seagrass beds.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through Florida, the Gulf of Mexico, and the Caribbean down to South America.
Description
A charming and compact bivalve featuring a classic fan shape with prominent, rounded radial ribs extending from the umbo to the scalloped margin. The exterior showcases rich reddish-brown tones with fine textured ridges, while the symmetrical auricles (ears) frame the beak.
Key Features
Nearly equilateral and equivalve fan shape, distinguished by approximately 18 to 22 well-rounded radial ribs and unequal "ears" (auricles) at the hinge line typical of the Argopecten genus.
Collector Value
Low to moderate commercial value, highly popular among beginner and intermediate beachcombers and crafters due to their vibrant colors and symmetrical beauty. Typically sold in bulk at shell shops.
Condition Notes
The shell appears to be in Fine to Gem condition, intact with vibrant natural coloration, well-defined ribs, and no apparent major chips, cracks, or boring sponge holes.
Interesting Facts
Unlike many bivalves, calico scallops are capable of swimming short distances by rapidly clapping their valves together to expel water, and they possess dozens of tiny, bright blue eyes along the mantle edge that can detect light and shadow.
Ecological Role
Serves as an important prey species for various marine predators including fish, crabs, and sea stars. They are filter feeders that help maintain water clarity by consuming suspended phytoplankton.
Similar Species
Rough Scallop (Argopecten nucleus) and Atlantic Bay Scallop (Argopecten irradians). The Bay Scallop tends to be slightly larger with flatter ribs, while the Calico Scallop has more rounded ribs and is generally more convex.
Beach Finding Tips
Look along high tide wrack lines on white quartz sand beaches in Florida and the Gulf Coast, especially after strong onshore winds or tropical storms. Early morning hours before other beachcombers arrive yield the best finds.