Rough Scallop (Atlantic Deep-Sea Scallop or Calico Scallop variant)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled), whole shell valve, fan shape
Species
Argopecten gibbus
Shell Type
Bivalve (two-shelled), whole shell valve, fan shape
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 inches in length and width, which is average for this species. Adults typically range from 1 to 2.5 inches.
Color & Pattern
Whitish-gray base with faint brownish-orange mottling and square-spotted patterns along the radial ribs and margins. Colors appear slightly sun-bleached and weathered from wave action.
Rarity
Common
Habitat
Shallow subtidal zones to moderately deep waters, preferring sandy or shelly substrates, often found in seagrass beds or open sandy flats.
Geographic Range
Western Atlantic Ocean, from North Carolina through the Gulf of Mexico, including the coast of Texas (Surfside Beach) down to the Caribbean.
Description
An attractive, classic fan-shaped bivalve shell featuring prominent, rounded radial ribs radiating from the umbo. The margins are crenulated to form a tight seal when closed, and the auricles (ears) at the hinge are somewhat asymmetrical.
Key Features
Equilateral to slightly inequilateral fan shape, well-defined rounded radial ribs (usually around 18-22), and characteristic mottled brownish patterns on a lighter background.
Collector Value
Low to Moderate value. Very common in shell shops and beach markets, making it an accessible and affordable piece for beginner beachcombers and collectors.
Condition Notes
Fair to Good condition. Shows minor wear and bleaching from beach tumbling, with intact margins and visible ribbing, though some natural coloration has faded.
Interesting Facts
Scallops are unique among bivalves because they can swim by rapidly clapping their shells together to expel water. They also possess dozens of simple blue eyes along the mantle edge that can detect light and shadow.
Ecological Role
Serves as an important prey species for crabs, sea stars, fish, and shorebirds. They filter feed on microscopic plankton, helping to maintain water clarity in coastal ecosystems.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to be slightly wider with flatter ribs, and the Rough Scallop (Aequipecten muscosus), which has sharper, more scaly ribs.
Beach Finding Tips
Look along the wrack line on sandy Texas beaches after high tide or following a storm, where lightweight bivalves are frequently washed ashore.
Notes
Surfside beach Texas