Coquina Clam (also known as Butterfly Shell, Bean Clam, or Pipi)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Donacidae, Genus: Donax, Species: Donax variabilis · Donacidae (Bean clam family) · Bivalve (two-shelled), whole paired or matched valves, wedge/oval shape
Species
Donax variabilis
Shell Type
Bivalve (two-shelled), whole paired or matched valves, wedge/oval shape
Family
Donacidae (Bean clam family)
Size
Approximately 0.5 to 0.75 inches (12-20 mm) in length, which is typical for adult specimens of this species; they rarely exceed 1 inch.
Color & Pattern
Extremely variable coloration featuring shades of purple, pink, yellow, orange, white, and brown, often with concentric growth bands or radial rays. The exterior is glossy with smooth to finely striated textures, and the interior matches the exterior hues with a purplish or dark tint along the margins.
Rarity
Very Common, frequently washing ashore in great numbers along sandy coastlines.
Habitat
Found primarily in the swash zone of high-energy sandy ocean beaches, burrowing rapidly into the sand in the intertidal zone.
Geographic Range
Western Atlantic Ocean, ranging from Virginia down through Florida, the Gulf of Mexico, and into the Caribbean.
Description
A small, brightly colored, wedge-shaped bivalve shell with a glossy finish. The surface exhibits delicate concentric growth lines and sometimes faint radial rays. The posterior end is slightly truncated, and the anterior is elongated and rounded, giving it a distinctive asymmetrical wedge profile.
Key Features
Wedge-like asymmetrical shape, highly variable and vibrant color polymorphism, glossy exterior texture, and fine concentric growth lines without heavy ribbing.
Collector Value
Low monetary value due to abundance, but highly prized by casual beachcombers and crafters who use them to create intricate shell art, jewelry, and mosaics.
Condition Notes
Specimens appear intact 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 sand using their muscular foot when exposed by receding waves. They feed by filtering microscopic plankton from the water column.
Ecological Role
Serves as an important food source for numerous shorebirds, fish, and crabs, acting as a vital link in the marine food web of sandy beach ecosystems.
Similar Species
Donax fossor (Eastern Pacific coquina or variable wedge shell), which can be distinguished by subtle differences in geographic distribution and slight variations in shell proportions and sculpture.
Beach Finding Tips
Look along the wet sand in the swash zone of high-energy beaches right after a wave recedes. You will often see tiny bubbles or movements in the sand indicating a colony just beneath the surface.