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 (two-shelled clam), whole shell, fan-shaped
Species
Argopecten irradians
Shell Type
Bivalve (two-shelled clam), whole shell, fan-shaped
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches in width, which is average for this species. Adults typically range from 1.5 to 3 inches.
Color & Pattern
Striking and vibrant coloration with a distinct split appearance. The left half displays rich orange, brown, and yellowish tones, while the right half is a deep, striking purple. The surface appears polished or glossy, likely indicating a natural wet look or a light protective coating.
Rarity
Common, though bicolored or heavily saturated purple morphs in this condition are particularly prized finds for beachcombers.
Habitat
Found in shallow marine waters, typically in eelgrass beds, sandy flats, and bays, ranging from the intertidal zone down to about 10 meters depth.
Geographic Range
Western Atlantic Ocean, from Nova Scotia down to the Gulf of Mexico and the Caribbean Sea.
Description
An attractive, nearly symmetrical fan-shaped bivalve with prominent, rounded radial ribs and matching furrows. The auricles (ears) at the hinge are relatively even. The margin is deeply scalloped, reflecting the exterior ribs, and the surface texture is smooth yet strongly ribbed.
Key Features
Equilateral fan shape with well-defined radial ribs, distinct asymmetrical ears at the hinge, and vibrant, naturally occurring color variations including rare purple and orange splits.
Collector Value
Moderately high for exceptionally colorful or bicolored specimens. While common as plain grey or white beach shells, vivid purple and orange specimens like this are highly sought after by shellcrafters and collectors, typically valued between $5 and $20 depending on exact vibrancy.
Condition Notes
Gem condition. The shell is fully intact, retains brilliant natural coloration with no fading or bleaching, and shows no signs of erosion, boring sponge holes, or major structural damage.
Interesting Facts
Bay scallops possess up to 60 tiny, bright blue eyes along the mantle edge that can detect light, dark, and motion. Unlike most bivalves, they can swim actively by rapidly clapping their valves together to expel water.
Ecological Role
Bay scallops are filter feeders that help maintain water clarity in estuarine ecosystems. They serve as an important food source for crabs, sea stars, and fish, and support commercial fisheries.
Similar Species
Rough Scallop (Aequipecten gibbus) and Calico Scallop (Argopecten gibbus), which tend to be more convex and have mottled patterns rather than solid distinct color blocks.
Beach Finding Tips
Look along shallow bay beaches and seagrass bed margins at low tide, especially after a storm or strong offshore winds that wash up delicate bivalves.