Atlantic Bay Scallop (also known as Bay Scallop)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten irradians · Pectinidae (Scallop family) · Bivalve (single valve present), fan-shaped scallop shell
Species
Argopecten irradians
Shell Type
Bivalve (single valve present), fan-shaped scallop shell
Family
Pectinidae (Scallop family)
Size
Approximately 2 inches (5 cm) in width. Typical adult size ranges between 1.5 to 3 inches (4 to 7.5 cm).
Color & Pattern
Displays a dusty reddish-pink to brownish-rose exterior hue with faint white concentric growth lines and lighter shading along the prominent radial ribs.
Rarity
Common to Very Common along beaches near coastal bays and estuaries within its range.
Habitat
Subtidal coastal waters, shallow estuaries, bays, and seagrass (eelgrass) beds over sandy or muddy substrate.
Geographic Range
Western Atlantic Coast, ranging from Massachusetts south to Florida and along the Gulf Coast to Texas.
Description
A classic fan-shaped single valve of a scallop featuring prominent, rounded radial ribs radiating from the umbo to a scalloped outer margin. The shell exhibits small, symmetrical auricles (ears) on either side of the hinge area, characteristic of true scallops.
Key Features
Roughly 18–22 distinct, flat-topped radial ribs; prominent wing-like auricles (ears) near the beak; symmetrical fan-shaped outline; characteristic scallop margin.
Collector Value
Low commercial or financial value due to its commonality, but widely appreciated by craft makers, decorative artists, and beachcombers for its classic iconic shape.
Condition Notes
Fair to Good condition. The valve retains its natural shape and scallop edging, though the surface shows light weathering and calcification typically seen in beach-found shells.
Interesting Facts
Bay scallops possess dozens of tiny, bright blue eyes along the edge of their mantle that can detect movement and shadows. They are capable of swimming rapidly by clapping their valves together to propel themselves through water.
Ecological Role
Serves as an essential filter feeder purifying coastal water and provides a vital food source for crabs, sea stars, gulls, and humans. Highly sensitive to water quality and seagrass habitat loss.
Similar Species
Calico Scallop (Argopecten gibbus), which typically displays brighter mottling or blotches of red and purple, and the Atlantic Deep-sea Scallop (Placopecten magellanicus), which is much larger with smoother, finer ribs.
Beach Finding Tips
Look along beach drift lines, bay shores, and tidal flats near seagrass beds, particularly after low tide or winter storms.