Atlantic Deep Sea Scallop / St. James Shell
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Placopecten, Species: P. magellanicus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole shell, fan-shaped
Species
Placopecten magellanicus
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped
Family
Pectinidae (Scallop family)
Size
Approximately 2 to 3.5 inches across, which is typical for beach-worn specimens. Adults in deep water can grow up to 6-9 inches.
Color & Pattern
Predominantly off-white, light gray, and weathered chalky white with subtle darker gray or brownish radial bands near the hinge line. Sun-bleached and worn with no remaining periostracum.
Rarity
Common
Habitat
Marine environment, typically found on sandy or gravelly seabeds ranging from the intertidal zone down to depths of over 100 meters.
Geographic Range
Northwest Atlantic Ocean, from Labrador and Newfoundland down to Cape Hatteras, North Carolina.
Description
A classic fan-shaped bivalve shell featuring prominent radial ribs and symmetrical auricles (ears) flanking the straight hinge line. The exterior surface shows fine concentric growth lines intersecting with the main ribs. The texture is chalky due to weathering, and the margins are finely crenulated.
Key Features
Symmetrical fan shape, straight hinge line with distinct unequal or equal auricles (ears), prominent radial ribbing, and a relatively smooth interior with a single central muscle scar.
Collector Value
Low to Moderate. While widely collected and very popular for crafts and casual beachcombing, weathered beach-worn specimens hold little monetary value compared to pristine live-taken deep-water specimens.
Condition Notes
Good to Fair condition. The specimens are intact whole valves showing signs of beach-wear, weathering, and complete loss of original bright pigmentation/periostracum.
Interesting Facts
Scallops are among the few bivalves that can swim actively by rapidly clapping their valves together to expel water. They also possess dozens of simple blue eyes along the mantle edge that can detect light and shadow.
Ecological Role
Scallops serve as an important food source for various marine predators including sea stars, crabs, fish, and gulls. They are filter feeders that help clear particulate matter from the water column.
Similar Species
Calico Scallop (Argopecten gibbus) and Bay Scallop (Argopecten irradians), which are generally smaller and more vividly patterned with distinct color variations.
Beach Finding Tips
Look along high tide wrack lines on ocean-facing sandy beaches after severe storms or strong offshore winds.