Atlantic Bay Scallop
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: Argopecten irradians · Pectinidae (Scallop family) · Bivalve (fan-shaped, single valve shown)
Species
Argopecten irradians
Shell Type
Bivalve (fan-shaped, single valve shown)
Family
Pectinidae (Scallop family)
Size
Approximately 1.5 to 2 inches in width. This is a common mid-range size for a mature specimen of this subspecies (A. i. concentricus).
Color & Pattern
Shows a classic mottled pattern with radiating grayish-brown bands over a cream to yellowish-tan base. The colors appear natural but slightly weathered by tide action. The interior of this species typically features a white iridescent sheen with a purple blotch near the hinge muscle scar.
Rarity
Common; frequently found on North Carolina beaches, though finding a perfectly matched pair of valves is less common than finding single valves.
Habitat
Found in shallow water, particularly in seagrass beds (eelgrass) and sandy or muddy bottoms within bays and estuaries.
Geographic Range
Western Atlantic from Cape Cod to Florida and the Gulf of Mexico. This specimen was found at Holden Beach, NC, which is within the prime range for the Atlantic/Southern subspecies.
Description
A classic fan-shaped shell featuring 17 to 22 radiating ribs. The ribs are rounded and prominent, creating a corrugated texture. The shell has two 'ears' or auricles at the hinge, which are roughly equal in size. The exterior texture is slightly rough from growth lines crossing the ribs.
Key Features
Symmetrical fan shape, nearly equal-sized ears (auricles) at the hinge, and 17-22 well-defined rounded ribs. The lack of spines distinguishes it from the Lion's Paw.
Collector Value
Minimal monetary value ($1-$5) due to its abundance, but highly desired by casual collectors for its iconic 'classic shell' aesthetic. High educational/sentimental value for regional collections.
Condition Notes
Good condition. The ribs are intact and the auricles are present, though the edges show slight 'beach-worn' erosion. Collectibility grade: Fine.
Interesting Facts
The living animal has up to 100 bright blue eyes along the edge of its mantle that can detect motion. Unlike many bivalves, they are capable of swimming short distances by rapidly clapping their valves together.
Ecological Role
Filter feeders that improve water quality. They are a vital food source for crabs, sea stars, and various shorebirds. They are also commercially harvested for their large adductor muscle.
Similar Species
Calico Scallop (Argopecten gibbus) which is usually more colorful with pink/red spots and prefers deeper offshore water; Rough Scallop (Aequipecten muscosus) which has small scales or spines on the ribs.
Beach Finding Tips
Best found after storms or at low tide near inlets and sound-side beaches where seagrass remains are present. Look in the 'shell hash' lines at Holden Beach.
Notes
Holden Beach, NC