Calico Scallop (also known as the Atlantic Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: A. gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), shell fragment showing internal hinge and adductor muscle scar area
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), shell fragment showing internal hinge and adductor muscle scar area
Family
Pectinidae (Scallop family)
Size
The fragment measures approximately 1.5 inches across; full adult shells of this species typically range from 1.5 to 2.5 inches in diameter.
Color & Pattern
The visible internal portion displays classic porcelain-white background with dark purple-black mottling around the central adductor scar area. The smaller separate fragment is a smooth, light beige exterior portion of a valve.
Rarity
Very Common, frequently washed up on North Carolina beaches, especially after storms.
Habitat
Found in shallow marine waters, typically from the low intertidal zone down to depths of about 150 feet, inhabiting sandy bottoms, seagrass beds, and offshore shell gravel beds.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea.
Description
This specimen consists of shell fragments from the Atlantic Calico Scallop. The larger piece displays the smooth, polished interior with the prominent central muscle scar, while the smaller adjacent piece shows the ribbed exterior structure characteristic of the species.
Key Features
Rounded fan-shaped valves with distinct radial ribs, equivalve symmetry in whole specimens, and a purplish-black internal adductor muscle scar.
Collector Value
Low monetary value due to the fragmentary condition and common abundance, though popular for shell crafting and beginner collections.
Condition Notes
Fragmentary condition, water-worn edges. Fair collectibility grade as a beach fragment rather than a whole specimen.
Interesting Facts
Calico scallops are capable of swimming short distances by rapidly clapping their valves together to expel water, using a simple row of blue eyes along their mantle edge to detect motion.
Ecological Role
Acts as an active filter feeder improving water clarity, serves as an important food source for fish, rays, and sea turtles, and supports commercial fisheries in certain regions.
Similar Species
Bay Scallop (Argopecten irradians), which tends to be slightly larger with fewer, broader ribs and is found in shallower estuarine waters.
Beach Finding Tips
Look along North Carolina shell-rich beaches at low tide, especially following strong ocean swells and storms that churn up offshore beds.
Notes
NC