Calico Scallop (Alternating Calico Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve, whole individual valve, fan-shaped disc
Species
Argopecten gibbus
Shell Type
Bivalve, whole individual valve, fan-shaped disc
Family
Pectinidae (Scallop family)
Size
Approximately 1 inch (25 mm) in diameter, which is a medium-to-large size for this specific species. Adults typically range from 0.75 to 1.5 inches.
Color & Pattern
Attractive mottled and checkered pattern featuring warm reddish-brown and tan patches interspersed with stark white spots and streaks along the prominent ribs. The coloration is entirely natural and vibrant.
Rarity
Common
Habitat
Found in shallow marine waters, typically in sandy substrates, seagrass beds, and offshore shoals from the low intertidal zone down to depths of 150 feet or more.
Geographic Range
Western Atlantic Ocean, extending from North Carolina southward through the Florida Keys, the Gulf of Mexico, and into the Caribbean Sea.
Description
A charming, neatly rounded fan-shaped bivalve with roughly 18 to 22 strong, rounded radial ribs extending from the umbo to the margin. The exterior showcases a delightful calico patchwork of brown and white. The margins are slightly crenulated to match the external ribbing, creating a clean, symmetrical profile.
Key Features
Symmetrical, rounded fan shape with 18-22 prominent, rounded radial ribs and characteristic mottled red-brown and white coloration.
Collector Value
Inexpensive and widely accessible, making it a favorite for beginner shell collectors and crafters alike. Individual specimens generally have nominal commercial value unless part of a matched pair or exceptionally large.
Condition Notes
Fine to Gem condition. The shell is fully intact with crisp, un-worn ribs, bright natural coloration, and no visible major cracks or predator boring holes.
Interesting Facts
Unlike many bivalves that remain stationary, calico scallops can swim short distances by rapidly clapping their valves together to expel water, using a simple row of tiny blue eyes along their mantle edge to detect motion.
Ecological Role
Serves as an important prey item for various marine carnivores including sea stars, fish, and octopuses. They filter phytoplankton from the water column, aiding in water clarity.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to have a more inflated shell and fewer, broader ribs (usually 17 or fewer).
Beach Finding Tips
Best found by beachcombing along Gulf and Atlantic Florida shores following rough weather or high tides, especially near passes and inlets where offshore shell deposits wash ashore.