Calico Scallop
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole shell, fan shape
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell, fan shape
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches in width and length, which is average for an adult specimen of this species. Adults typically range from 1.5 to 2.5 inches.
Color & Pattern
Vibrant pattern of mottled reddish-brown, pink, and burgundy blotches and zigzag markings over a creamy-white or yellowish base. The colors are entirely natural and vivid, showcasing characteristic calico patterning with prominent rounded radial ribs.
Rarity
Common
Habitat
Shallow marine waters, typically found in offshore sandy or shelly substrates, sea grass beds, and sometimes down to moderate depths. Entirely marine.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through the Gulf of Mexico, the Caribbean, and down to South America.
Description
An attractive and classic bivalve featuring a symmetrical fan shape with approximately 18 to 22 well-rounded, prominent radial ribs. The surface is textured and rugged due to the ribs, with sharply defined growth lines crossing the exterior. The hinge area displays well-formed auricles (ears), with the anterior and posterior ears being somewhat unequal in size. The margins are deeply fluted, matching the internal contours of the ribs.
Key Features
Symmetrical rounded fan shape, roughly 18-22 prominent, rounded radial ribs, characteristic mottled reddish-brown calico color pattern, and uneven ear-like projections at the hinge.
Collector Value
Moderately sought after by beachcombers and casual shell collectors for their bright, cheerful colors. While very common and inexpensive to purchase individually (usually under a few dollars), high-grade, brightly colored specimens are prized for crafts and display jars.
Condition Notes
Gem to Fine grade. The shell is fully intact with no major chips along the wavy margin, excellent color retention with zero bleaching, and no visible predator boring holes or barnacle attachments.
Interesting Facts
Unlike many bivalves that burrow or cement themselves, Calico Scallops are capable of swimming short distances by rapidly clapping their valves together to expel water. They also possess dozens of tiny, glowing blue eyes along the mantle edge that can detect light and shadow.
Ecological Role
Serves as an important prey species for numerous marine predators including sea stars, octopuses, rays, and carnivorous gastropods. They are filter feeders that help clean the water column by consuming microscopic plankton. Populations can fluctuate drastically from year to year.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to have slightly flatter ribs and is generally found in shallower, inshore seagrass beds rather than offshore waters.
Beach Finding Tips
Best found by beachcombing on Gulf or Atlantic coastlines immediately following a storm or during extremely low tides. Look along the high tide drift lines where lightweight bivalve shells wash ashore.