Atlantic Calico Scallop (also known as Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole individual valve (single valve shown, fan-shaped)
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole individual valve (single valve shown, fan-shaped)
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches in width, which is average for an adult specimen of this species. Adults typically range from 1.5 to 2.5 inches.
Color & Pattern
Rich reddish-pink base coloration with subtle mottled or zigzag patterns of lighter pink and white patches. The color appears natural though slightly faded in worn spots where the outer layer is chipped away, revealing the white calcium carbonate beneath.
Rarity
Very Common. This is a frequently encountered species washed up on beaches throughout its native range, particularly along the southeastern United States and Gulf Coast.
Habitat
Shallow marine waters, typically found in sandy areas, shell gravel, or seagrass beds from the low intertidal zone down to depths of about 150 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, the Caribbean, and south to the West Indies and Brazil.
Description
A classic, attractive bivalve featuring a symmetrical fan shape with distinct, rounded radial ribs extending from the pointed umbo at the hinge to the scalloped margin. The exterior surface shows well-defined corrugated ridges and natural growth lines, giving it a pleasing textured feel.
Key Features
Nearly equilateral, rounded fan shape; prominent, evenly spaced radial ribs (typically around 18-22 ribs); unequal auricles (ears) at the hinge line; and characteristic mottled red/pink coloration.
Collector Value
Low to Moderate monetary value due to its abundance, but highly prized by casual beachcombers and crafters for creating shell art, jewelry, and coastal displays. Specimens with exceptional vibrant purple or deep orange colors command higher interest.
Condition Notes
Fair to Good condition. The single valve is structurally intact with a clear margin and distinct ribs, but shows some minor surface chips and peeling on the outer layer where white patches are exposed, typical of a beach-worn specimen.
Interesting Facts
Unlike many bivalves that burrow and remain stationary, Calico Scallops are capable of swimming short distances by rapidly clapping their valves together to expel water, allowing them to escape predators like sea stars and predatory snails.
Ecological Role
Calico scallops serve as an important food source for numerous marine predators including fish, rays, sea turtles, and whelks. As filter feeders, they also help maintain water clarity by consuming suspended phytoplankton and organic particles.
Similar Species
Rough Scallop (Argopecten nucleus) and Bay Scallop (Argopecten irradians). Bay scallops tend to be slightly larger with flatter ribs and inhabit shallower grass flats, while Calico scallops prefer deeper water and have more rounded ribs.
Beach Finding Tips
Look along high-tide wrack lines on Atlantic and Gulf Coast beaches, especially after storms or heavy winds. Calm mornings following an incoming high tide often yield the best assortment of whole valves.