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 with asymmetrical auricles (ears)
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped with asymmetrical auricles (ears)
Family
Pectinidae (Scallop family)
Size
Approximately 1.25 inches in width and height, which is typical for an adult Atlantic Calico Scallop. Adults generally range from 1 to 2 inches.
Color & Pattern
Displays a mottled pattern of purplish-brown, reddish-brown, and white flecks on a pale background, creating the characteristic 'calico' appearance. The colors are entirely natural and vivid. The exterior features well-defined radial ribs, while the interior shows faint purple shading.
Rarity
Common to Very Common. Frequently washed up on beaches throughout its range, especially following storms or rough sea conditions.
Habitat
Found in shallow marine waters, typically in sandy substrates, seagrass beds, or offshore shell gravel beds. Generally inhabits depths from the low intertidal zone down to about 160 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, the Caribbean, and south to Bermuda and parts of South America.
Description
A charming and classic fan-shaped bivalve with roughly 18 to 22 prominent, rounded radial ribs. The shell exhibits slightly unequal 'ears' (auricles) at the hinge line, a classic hallmark of the scallop family. The margins are scalloped to match the external ribbing, and the surface has a fine, granular texture.
Key Features
Distinguished by its roughly circular-to-fan shape, strongly convex valves, equal or nearly equal radial ribs, and the distinct mottled calico coloration pattern of reddish-brown and white.
Collector Value
Low to Moderate commercial and collector value. While extremely popular for crafts, jewelry, and beginner collections due to their abundance and pretty patterns, individual specimens hold little monetary value, typically worth a few cents to a dollar.
Condition Notes
Good to Fine condition. The shell is fully intact with sharp marginal ridges and well-preserved natural coloration. Minimal wear along the edges, making it a very nice representative specimen for a casual collection.
Interesting Facts
Unlike many bivalves that burrow and stay put, calico scallops are capable of swimming. By rapidly clapping their valves together, they expel water to jet-propel themselves away from predators like starfish. They also possess dozens of tiny, bright blue eyes along their mantle edge that can detect light and motion.
Ecological Role
Calico scallops serve as an important prey item for various marine predators, including sea stars, crabs, fish, and gulls. They are filter feeders that help clear particulate matter from the water column, contributing to water quality.
Similar Species
Bay Scallop (Argopecten irradians), which tends to have slightly flatter shells, fewer ribs (usually 17), and is typically found in shallower inshore grass flats rather than offshore beds.
Beach Finding Tips
Look along high tide lines on Atlantic and Gulf beaches in the southeastern United States, particularly after windy weather or winter storms. Scallop shells wash ashore easily due to their lightweight, buoyant shape.