Atlantic Calico Scallop (or general Calico Scallop fragment/juvenile)
Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Pectinidae, Genus: Argopecten, Species: A. gibbus · Pectinidae (Scallop family) · Bivalve (two-shelled mollusk), fragment, fan shape
Species
Argopecten gibbus (fragment)
Shell Type
Bivalve (two-shelled mollusk), fragment, fan shape
Family
Pectinidae (Scallop family)
Size
Approximately 0.5 to 0.75 inches across, representing a broken fragment or juvenile of a species that typically grows to 1.5 to 2.5 inches.
Color & Pattern
Deep reddish-brown to dark chocolate coloration with pronounced vertical ribs. The colors appear natural and glossy, possibly wet or naturally polished by wave action.
Rarity
Very Common, though specific complete specimens in gem condition require searching; this is a common beach fragment.
Habitat
Shallow subtidal marine waters, typically found on sandy or shelly bottoms, often associated with seagrass beds.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through the Gulf of Mexico, Caribbean, and down to South America.
Description
A small, fan-shaped bivalve shell fragment characterized by strong, prominent radial ribs and deep furrows. The exterior exhibits a rich, dark brown hue with sturdy structural ridges designed to provide strength while maintaining a lightweight profile.
Key Features
Prominent, evenly spaced radial ribs (costae), fan-like triangular shape, and a uniform deep brown coloration typical of certain pectinid color morphs.
Collector Value
Low monetary value due to being a broken fragment, but holds sentimental or educational value for amateur beachcombers.
Condition Notes
Worn fragment with broken edges. The hinge and auricles (ears) are missing, indicating high wave energy exposure. Collectibility grade: Poor (fragment only).
Interesting Facts
Scallops are among the few bivalves that can swim by rapidly snapping their valves together to jet-propel themselves away from predators like sea stars.
Ecological Role
Scallops serve as an important prey species for crabs, fish, and sea stars, and contribute to benthic-pelagic coupling by filtering suspended organic matter from the water column.
Similar Species
Atlantic Bay Scallop (Argopecten irradians), which tends to have slightly flatter ribs and a different geographic overlap in some regions.
Beach Finding Tips
Look in the wrack line on high-energy sandy beaches shortly after high tide or following a storm.