Calico Scallop (Also known as Chlamys gibba)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), fan-shaped, whole individual valve
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), fan-shaped, whole individual valve
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 inches in width and height, which is a standard adult size for this species. Typical adults range from 1 to 2 inches.
Color & Pattern
Mottled and splashed with vibrant shades of reddish-pink, orange, white, and subtle grayish-brown patches, giving it a calico appearance. Colors are natural and retain good brightness.
Rarity
Common, frequently found washed ashore by beachcombers along the southeastern United States and Gulf coasts.
Habitat
Shallow marine waters, predominantly found on sandy or shelly substrates in seagrass beds and offshore banks, ranging from the intertidal zone down to moderate depths.
Geographic Range
Western Atlantic Ocean, extending from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea.
Description
An attractive, roughly symmetrical fan-shaped bivalve shell featuring prominent radiating ribs and distinct, winged auricles (ears) at the hinge line. The margins are scalloped to match the external ribs, creating a classic fluted scallop profile.
Key Features
Equivalve to slightly inequivalve rounded fan shape, approximately 18 to 22 radiating ribs, and asymmetrical ears at the hinge with the anterior ear slightly larger than the posterior.
Collector Value
Low to moderate commercial and collector value. Highly popular among casual beachcombers and beginner crafters, but common enough that individual specimens have nominal monetary value (usually sold cheaply in bulk).
Condition Notes
Good beach-worn condition. Intact single valve with minor surf wear on the margins, but maintaining most of its original color pattern and structural integrity. Grade: Good.
Interesting Facts
Unlike many bivalves that burrow or remain sedentary, calico scallops can swim short distances by rapidly clapping their valves together to expel water, using a series of simple blue eyes along their mantle edge to detect light and shadow.
Ecological Role
Serves as an important prey item for various marine carnivores including sea stars, rays, and carnivorous gastropods. They also act as filter feeders, helping to maintain water clarity.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to be slightly more rounded with flatter ribs, and the Rough Scallop (Aequipecten muscosus), which features more pronounced scale-like projections on the ribs.
Beach Finding Tips
Look along high-tide shell lines on sandy beaches following storms or heavy onshore winds, particularly in Florida and North Carolina.