Calico Scallop (Atlantic Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: A. gibbus · Pectinidae (Scallop family) · Bivalve; single valve (left valve fragment); fan-shaped
Species
Argopecten gibbus
Shell Type
Bivalve; single valve (left valve fragment); fan-shaped
Family
Pectinidae (Scallop family)
Size
Approximately 1 to 1.5 inches in diameter. This is a common size for a juvenile or sub-adult of this species, which typically reaches 2 to 3 inches.
Color & Pattern
Vibrant and mottled pattern featuring alternating bands of creamy white, golden yellow, and deep purple-maroon. The radiating ribs show a 'calico' or checkered spotting typical of the species. Colors appear natural and well-preserved rather than bleached.
Rarity
Very Common. This is one of the most frequently found shells along the South Carolina coast, particularly at Myrtle Beach, though finding perfectly colorful specimens is always a treat.
Habitat
Subtidal marine environment, typically found at depths of 30 to 120 feet on sandy or shelly sea floors. They are not intertidal by nature but wash up frequently after storms.
Geographic Range
Western Atlantic, ranging from North Carolina south through the Gulf of Mexico, the Caribbean, and down to Brazil.
Description
A classic fan-shaped bivalve with roughly 17 to 23 radiating ribs. The exterior surfaces are covered in deep, blocky color patterns. The ribs are rounded and separated by deep grooves. This fragment showcases the robustness of the valve and the characteristic 'ears' (auricles) though they are partially worn in this specimen.
Key Features
Nearly circular (disk-like) shape when whole, roughly equal-sized auricles (the 'ears' at the hinge), and a distinctively mottled 'calico' color pattern that differentiates it from the Bay Scallop.
Collector Value
Low monetary value ($0.50 - $2.00) due to extreme abundance. However, they are highly desired by hobbyists for crafts and decorative collections because of their diverse and brilliant color variations. A 'set' of matched valves is more valuable than single beach-worn valves.
Condition Notes
Good beach condition. It is a single valve (common for beach finds) with some wear on the hinge area and the lower margin. The color saturation is excellent, suggesting it has not been exposed to the sun for long. Collectibility Grade: Good.
Interesting Facts
Unlike many bivalves, Calico Scallops can swim by rapidly snapping their valves together, creating a primitive form of jet propulsion. They also have a row of tiny, bright blue 'eyes' along the edge of their mantle that can detect light and movement.
Ecological Role
Active filter feeders that help clear the water of plankton and organic detritus. They serve as a vital food source for sea stars, octopuses, and various crab species. Commercial harvesting is regulated to prevent overfishing.
Similar Species
The Atlantic Bay Scallop (Argopecten irradians) which is usually drabber (gray/brown) and flatter, and the Lion's Paw (Nodipecten nodosus) which is much larger with large nodes or 'knobs' on the ribs.
Beach Finding Tips
In Myrtle Beach, look for these after a strong offshore storm or during low tide. They are often found in the 'shell hash' lines. Sifting through the debris at the water's edge is the most effective way to find bright specimens.
Notes
Myrtle Beach SC