Coquina Clam (Butterfly Shell, Bean Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Donacidae, Genus: Donax, Species: Donax variabilis · Donacidae (Coquina family) · Bivalve, whole shell, wedge or triangular shape
Species
Donax variabilis
Shell Type
Bivalve, whole shell, wedge or triangular shape
Family
Donacidae (Coquina family)
Size
Approximately 0.5 to 0.75 inches, which is average for this species. Adults typically range from 0.5 to 1 inch.
Color & Pattern
Extremely variable coloration featuring shades of yellow, orange, purple, pink, white, and blue, often with radiating rays or concentric banding. The exterior shows natural, vibrant glossy colors.
Rarity
Very Common
Habitat
Intertidal zone on high-energy, sandy ocean beaches, living just beneath the sand surface in the swash zone where waves break and wash ashore.
Geographic Range
Western Atlantic and Gulf of Mexico, ranging from Virginia down to Florida and along the Gulf coast to Texas.
Description
A small, colorful, wedge-shaped bivalve with a smooth, glossy exterior and fine concentric growth lines. The posterior end is slightly truncated while the anterior is elongated. Its vibrant array of colors and patterns makes it a favorite for beachcombers.
Key Features
Wedge-like triangular shape, highly variable and bright color polymorphism, smooth glossy surface, and fine concentric ridges near the margin.
Collector Value
Very low individual monetary value due to extreme abundance, but highly valued for crafts, shell art, and nostalgic beach collections.
Condition Notes
The specimen appears intact, fresh, and whole with bright natural coloration and minimal wear, grading as Fine to Gem condition.
Interesting Facts
Coquina clams are famous for their ability to rapidly burrow back into the wet sand using their muscular foot when exposed by receding waves. They move up and down the beach with the tides to maintain their position in the swash zone.
Ecological Role
Serves as a crucial food source for numerous shorebirds, fish, and crabs, and acts as an important filter feeder in the intertidal sandy beach ecosystem.
Similar Species
Donax denticulatus (Caribbean coquina), which tends to have more prominent denticles along the shell margin.
Beach Finding Tips
Look in the wet swash zone of sandy ocean beaches during low tide. Watch for tiny bubbles or tiny disturbances in the sand as they burrow, or use a beach sifter in the foamy wash.
Notes
Ocean isle beach