Atlantic Bay Scallop (Common Bay Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten irradians · Pectinidae (Scallop family) · Bivalve (two-shelled), whole valve, fan-shaped disc
Species
Argopecten irradians
Shell Type
Bivalve (two-shelled), whole valve, fan-shaped disc
Family
Pectinidae (Scallop family)
Size
Approximately 2 inches in width, which is typical for a mature specimen of this species. Adults generally range from 1.5 to 3 inches.
Color & Pattern
Vibrant, warm reddish-orange coloration on the exterior with subtle concentric growth lines crossing the radiating ribs. Colors appear completely natural and well-preserved with no extreme sun-bleaching. The interior typically shows a matching orange tint or white porcelain finish with a purple-tinted adductor scar.
Rarity
Common, frequently found on eastern North American beaches, though vibrant whole single valves in this pristine condition are always a welcome find.
Habitat
Found in shallow marine waters, typically in bays and estuaries, resting on sandy bottoms or amongst seagrass beds (such as eelgrass) from the intertidal zone down to about 60 feet.
Geographic Range
Western Atlantic Ocean and Gulf of Mexico, ranging from Nova Scotia down to the Gulf of Mexico and Caribbean Sea.
Description
A classic, beautifully symmetrical fan-shaped bivalve shell featuring prominent, evenly spaced radiating ribs that terminate in a scalloped margin. The hinge area displays distinct, unequal auricles (ears) characteristic of the genus, creating a classic triangular beak. The texture is finely ridged and matte with wonderful natural warm tones.
Key Features
Distinguished by its nearly symmetrical rounded-triangular outline, approximately 17 to 20 rounded radiating ribs, and unequal "ears" (auricles) at the hinge line, separating it from other scallop families.
Collector Value
Low to moderate commercial value, highly popular among casual beachcombers and crafters due to their bright colors and iconic shape. Whole, brightly colored single valves usually sell for a nominal price or are treasured personal keepsakes.
Condition Notes
Fine to Gem condition. The single valve is intact with sharp margins, vibrant natural color, minimal wear, and no visible predatory boring holes or major structural damage.
Interesting Facts
Bay scallops are famously capable of swimming by rapidly snapping their valves together to expel water, jetting themselves away from predators. They also possess dozens of tiny, bright blue eyes along the edge of their mantle that can detect light and motion.
Ecological Role
Bay scallops serve as both filter feeders that help maintain water clarity and as an important food source for various fish, crabs, and sea turtles. Their populations are sensitive to water quality changes and algal blooms.
Similar Species
Calico Scallop (Argopecten gibbus), which is more globose and has mottled brownish-purple patterns rather than solid uniform orange bands; and the Sea Scallop (Placopecten magellanicus), which is much larger with smoother, flatter ribs.
Beach Finding Tips
Look along protected bays, salt marshes, and grassy intertidal zones during extreme low tides or immediately following seasonal storms that churn up shallow seagrass beds.