Coquina Clam (also known as Butterfly Shell, Bean Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Donacidae, Genus: Donax, Species: Donax variabilis · Donacidae (Bean Clam family) · Bivalve, whole shell, oval-triangular shape
Species
Donax variabilis
Shell Type
Bivalve, whole shell, oval-triangular shape
Family
Donacidae (Bean Clam family)
Size
Approximately 0.5 inches (12-15 mm) in length, which is average for this species. Adults typically range between 0.5 to 1 inch.
Color & Pattern
Highly variable color polymorphism including shades of white, pink, yellow, orange, purple, and blue, often featuring radial rays or concentric growth banding. Colors are natural and glossy on this fresh specimen.
Rarity
Very Common
Habitat
Shallow intertidal zones of high-energy sandy beaches, surf zones where waves break and wash up onto the shore.
Geographic Range
Western Atlantic from Virginia south to Florida, the Gulf of Mexico, and parts of the Caribbean.
Description
A tiny, colorful, wedge-shaped bivalve with a smooth yet finely striated exterior. The shell exhibits strong, concentric growth lines and a wedge-like profile designed to burrow rapidly into shifting sands.
Key Features
Wedge shape, asymmetrical profile with a short posterior end and longer anterior end, glossy surface, and extreme color variation.
Collector Value
Low individual commercial value due to high abundance, but highly prized by beachcombers for creating decorative shell crafts and colorful collages.
Condition Notes
Gem condition. The shell is fully intact, retains vibrant natural coloration, shows no noticeable wear or predator boring, and has an intact hinge.
Interesting Facts
Coquina clams are famous for their remarkable ability to burrow back into the wet sand within seconds of a wave receding, using their muscular foot. They feed by filtering microscopic plankton from the water column.
Ecological Role
Serves as an essential food source for shorebirds, fish, and crabs, linking primary producers to higher trophic levels in sandy beach ecosystems.
Similar Species
Donax fossor (Eastern Little Coquina), which tends to be smaller and less brightly colored, and Donax denticulatus found further south in the Caribbean.
Beach Finding Tips
Look along the wash zone of sandy ocean beaches at low tide. Watch for tiny bubbles or V-shaped depressions in the wet sand as the water recedes.