Atlantic Calico Scallop (also known simply as the Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled clam), whole shell valve, fan-shaped with radiating ribs
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled clam), whole shell valve, fan-shaped with radiating ribs
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 inches in diameter, which is typical for an adult Calico Scallop. Adults generally range from 1 to 2.5 inches.
Color & Pattern
Mottled pattern featuring shades of purplish-brown, reddish-brown, and white arranged in irregular patches and dashes resembling calico fabric. The coloration is natural and shows good pigment retention, typical of a shell found freshly on the beach.
Rarity
Common to Very Common, especially in specific regions like Sanibel Island, Florida, where tidal currents deposit thousands of shells along the shore.
Habitat
Shallow marine waters, typically found living on sandy or shelly bottoms, seagrass beds, and offshore shoals from the low intertidal zone down to depths of about 150 feet.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina south through Florida, the Gulf of Mexico, the Caribbean, and down to the West Indies and South America.
Description
An attractive, roughly symmetrical fan-shaped bivalve with distinctly convex valves. The exterior features numerous prominent radiating ribs (typically around 18 to 22) crossed by fine concentric growth lines. The auricles (ears) at the hinge line are unequal in size, a classic trait of scallops.
Key Features
Rounded fan shape, convex valves, asymmetrical hinge ears, and the characteristic mottled reddish-purple 'calico' pattern on a whitish background.
Collector Value
Low to Moderate commercial value due to abundance, but highly prized by amateur beachcombers and crafters. Specimens with exceptional, vibrant colors or pristine condition command more interest.
Condition Notes
Good to Fine condition. The shell appears intact with well-defined ribs and minimal edge wear, retaining a large portion of its natural color pattern with only slight fading from sun exposure.
Interesting Facts
Unlike many bivalves that burrow or cement themselves to surfaces, Calico Scallops are capable of active swimming. By rapidly clapping their valves together, they expel water to jet-propel themselves away from predators like starfish.
Ecological Role
Calico scallops serve as an important prey species for numerous marine animals including fish, rays, sea turtles, and crabs. They are filter feeders, helping to maintain water clarity by consuming phytoplankton and organic particulates.
Similar Species
Rough Scallop (Argopecten nucleus) and Atlantic Bay Scallop (Argopecten irradians). The Bay Scallop is typically larger with flatter ribs and is found in shallower estuarine grass beds, while the Calico Scallop has more rounded and convex valves.
Beach Finding Tips
Look along high-tide wrack lines on Gulf coast beaches, particularly after storms or heavy offshore winds. Sanibel Island and Captiva Island in Florida are legendary hotspots for finding these shells.
Notes
Sanibel