Atlantic Calico Scallop (Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve, whole single valve (left valve), fan-shaped disc
Species
Argopecten gibbus
Shell Type
Bivalve, whole single valve (left valve), fan-shaped disc
Family
Pectinidae (Scallop family)
Size
Approximately 1.25 inches in width and height, which is average for an adult specimen of this species. Adults typically range from 1 to 2 inches.
Color & Pattern
The exterior exhibits a creamy white or pale yellowish background overlaid with distinctive reddish-brown mottled patterns and streaks radiating from the umbo toward the outer margin. The colors appear natural and fairly well-preserved with distinct pattern definition.
Rarity
Very Common, frequently found washed up on beaches throughout the southeastern United States, especially after storms.
Habitat
Shallow subtidal marine environments, typically found on sandy bottoms, shell hash, and seagrass beds in waters ranging 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, and the Caribbean Sea.
Description
An attractive, nearly symmetrical bivalve shell featuring a classic rounded fan shape with prominent, evenly spaced radial ribs. The surface is textured with numerous rounded ribs extending from the beak to the crenulated margin, creating a scalloped edge. The hinge area possesses small, equal-sized auricles (ears).
Key Features
Rounded, nearly equilateral fan shape; approximately 18 to 22 strong radial ribs; equal-sized auricles at the hinge; and the characteristic calico mottling of reddish-brown spots on a lighter background.
Collector Value
Low to Moderate commercial value, highly popular among beginner beachcombers and casual collectors due to their attractive patterns and abundance. Typically sold in bulk in souvenir shops.
Condition Notes
Good to Fine condition. The valve is intact with well-preserved ribs and color patterns, showing only minor wear along the ventral margin, making it a pleasant specimen for a beachcomber collection.
Interesting Facts
Unlike many bivalves that burrow or cement themselves, Calico Scallops are capable of swimming actively by rapidly clapping their valves together to jet water out through the sides of their hinge, allowing them to escape predators.
Ecological Role
Calico scallops serve as an important food source for numerous marine predators including fish, rays, sea turtles, and crabs. They are filter feeders that help clear particulate matter from the water column, contributing to water clarity.
Similar Species
Rough Scallop (Acompsaster nucleus) and Atlantic Bay Scallop (Argopecten irradians). The Bay Scallop tends to have fewer, flatter ribs (usually 17 or fewer) and prefers shallower estuarine waters.
Beach Finding Tips
Look along high-tide wrack lines on sandy beaches of the southeastern US, particularly after rough weather or strong offshore winds. Low tide following a morning or evening tide change yields the best results.
Notes
Myrtle beach South Carolina USA