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 shown, fan-shaped shell)
Species
Argopecten irradians (High confidence)
Shell Type
Bivalve (single valve shown, fan-shaped shell)
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches (4-5 cm) in height; typical adult size ranges from 1.5 to 3 inches.
Color & Pattern
Shows shades of pastel pinkish-purple hues mixed with cream, tan, and off-white. The shell exhibits natural color variations along radial ribs, though slightly beach-worn or sun-faded.
Rarity
Common (frequently found washed up on beaches along the US Atlantic coast and Gulf Coast).
Habitat
Shallow coastal waters, estuarine bays, and eelgrass beds (Zostera marina) on sandy or muddy bottoms, typically in intertidal to subtidal zones down to 30 feet deep.
Geographic Range
Northwestern Atlantic coast, from Nova Scotia down to the Florida Keys and into the Gulf of Mexico.
Description
A classic fan-shaped bivalve shell showing prominent radiating ribs that fan outwards from the umbo. This single valve displays soft pinkish-mauve tones with pale yellow-beige undertones around the hinge region. The shell margin is undulating due to the distinct ribbing pattern.
Key Features
Symmetrical fan shape, distinct prominent radial ribs (usually 17-20 ribs in this species), winged ears at the base hinge, and undulating shell margin.
Collector Value
Low monetary value ($1 - $3 for common beach-found specimens) as it is widely available, but highly prized by casual beachcombers for its lovely shape and warm pink colors.
Condition Notes
Fair to Good condition. The shell shows moderate natural beach wear, minor edge chipping, and sun-bleaching near the hinge, but retains attractive pinkish coloration and well-defined radial ribs.
Interesting Facts
Bay scallops have dozens of bright blue eyes located along the edges of their mantle to detect light and movement, and they can swim quickly through the water column by clapping their valves together.
Ecological Role
Key filter feeder in estuarine ecosystems that helps maintain water clarity; vital prey for crabs, sea stars, gulls, and rays. Sensitive to habitat loss of seagrasses and coastal pollution.
Similar Species
Calico Scallop (Argopecten gibbus) which typically features more mottled red and brown blotches, and Sea Scallop (Placopecten magellanicus) which is much smoother and grows significantly larger.
Beach Finding Tips
Look along bayfront beaches, estuaries, and sheltered coastlines near seagrass beds, particularly after winter storms or low tides along the drift line.