Sunrise Donax, also known as the Coquina clam or butterfly shell
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Donacidae, Genus: Donax, Species: Donax variabilis · Donacidae (Bean clam and coquina family) · Bivalve (two-shelled clam), whole shell, wedge or triangular shape
Species
Donax variabilis
Shell Type
Bivalve (two-shelled clam), whole shell, wedge or triangular shape
Family
Donacidae (Bean clam and coquina family)
Size
Approximately 0.5 inches (12-15 mm) in width, which is average for an adult specimen of this species. Adults typically range from 0.4 to 0.75 inches.
Color & Pattern
Extremely vibrant and varied coloration ranging from bright yellow, orange, pink, purple, to white. This specific specimen exhibits a warm golden-orange base with subtle lighter banding toward the umbo and a distinct white apex. The colors are entirely natural and retain a glossy sheen.
Rarity
Very Common, frequently washing ashore by the thousands on southeastern US beaches.
Habitat
Found in high-energy sandy intertidal zones, surf beaches, and swash zones where waves continuously break and wash over the sand. Marine environment.
Geographic Range
Western Atlantic, extending from the mid-Atlantic coast of the United States down through Florida, the Gulf of Mexico, and into the Caribbean.
Description
A tiny, charming wedge-shaped bivalve with smooth, polished exterior valves and fine radial micro-sculpture near the margins. The shell features a pointed umbo and a solid, slightly jagged inner margin. Despite its small size, it commands attention due to its dazzling array of rainbow colors.
Key Features
Distinctive wedge or triangular profile, inequilateral shape with a short posterior and longer anterior end, smooth glossy texture, and high color polymorphism.
Collector Value
Low monetary value due to abundance, but highly prized by casual beachcombers and crafters who use them to make shell jewelry, wind chimes, and mosaics.
Condition Notes
Gem condition. The single valve is intact with no chips, cracks, or predator boring holes, retaining full vivid coloration and a glossy finish.
Interesting Facts
Coquina clams are famous for their ability to rapidly burrow back into the sand using their muscular foot when a wave recedes, preventing them from being washed away or eaten by shorebirds.
Ecological Role
Serves as a crucial food source for numerous shorebirds, fish, and crabs. They act as filter feeders, helping to clean nearshore waters by consuming phytoplankton and suspended organic matter.
Similar Species
Donax fossor (Eastern Pacific coquina), which tends to be more elongated and less brightly colored.
Beach Finding Tips
Look in the wet swash zone of sandy beaches on a receding tide. Stand still in the receding water and watch the sand for tiny bubbling holes where the clams are burrowing, or sift through shell lines deposited by high tide.