Atlantic Calico Scallop (also known simply 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
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches in diameter, which is typical for an adult Calico Scallop. Adults generally range between 1.5 and 2.5 inches.
Color & Pattern
Base color is predominantly off-white or cream with faint traces of orange-brown mottled patches or banding. The colors appear slightly sun-bleached, masking the typically more vibrant calico patterns of purples, reds, and oranges commonly seen in fresh specimens.
Rarity
Very Common. This is a species that washes ashore regularly along many southeastern United States and Gulf Coast beaches.
Habitat
Shallow marine waters, typically found in sandy or shelly substrates, often associated with seagrass beds from the low intertidal zone down to depths of about 160 feet (50 meters).
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea to South America.
Description
A classic fan-shaped bivalve featuring approximately 18 to 21 prominent, rounded radial ribs running symmetrically from the umbo (beak) to the gently scalloped ventral margin. The exterior surface is finely textured with microscopic concentric growth lines. The auricles (ears) at the hinge are somewhat asymmetrical, which is characteristic of the genus.
Key Features
Rounded, prominent radial ribs (usually 18-21), inequilateral ears at the hinge line with the anterior ear being slightly larger, and a distinctly convex or inflated right valve compared to the flatter left valve.
Collector Value
Low to moderate value. While extremely popular among casual beachcombers and crafters, they are too common for specialized advanced collections unless they possess exceptional, flawless color morphs. Typically valued at a few cents to a dollar individually.
Condition Notes
The shell is intact as a single valve, exhibiting mild weathering and sun-bleaching with reduced coloration. No major chips or predator bore holes are visible. Overall collectibility grade is Good.
Interesting Facts
Unlike most bivalves that burrow or remain sessile, calico scallops are capable of swimming actively by rapidly snapping their valves together to expel water, allowing them to escape predators like starfish.
Ecological Role
Calico scallops serve as an important food source for numerous marine predators including fish, rays, sea turtles, and crabs. They are filter feeders that help maintain water clarity by consuming suspended phytoplankton.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to be slightly larger with flatter ribs and is found in shallower estuarine seagrass beds rather than deeper offshore waters.
Beach Finding Tips
Look along high-tide wrack lines on sandy ocean-facing beaches, especially after storms or heavy onshore winds in Florida and North Carolina.