Pacific Purple-lip or Violet Bean Clam (also known as Donax shell)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Donacidae, Genus: Donax, Species: Donax punctatostriatus · Donacidae (Bean Clam family) · Bivalve (two-shelled), whole shell, wedge or bean-shaped
Species
Donax punctatostriatus
Shell Type
Bivalve (two-shelled), whole shell, wedge or bean-shaped
Family
Donacidae (Bean Clam family)
Size
Approximately 0.75 inches (1.9 cm) in length, which is average to slightly large for this species. Adults typically range from 0.5 to 1 inch.
Color & Pattern
Smooth, polished exterior featuring a striking deep purple patch fading into creamy white and translucent grey. The colors appear somewhat water-worn and smoothed by wave action, highlighting the natural nacreous purple interior peeking through.
Rarity
Common in its native range, though finding a specimen with such rich, intact purple coloration on a water-worn beach specimen is a delightful treat.
Habitat
Intertidal and shallow subtidal zones, typically buried just beneath the surface in high-energy sandy beaches and swash zones where waves continuously break.
Geographic Range
Eastern Pacific Ocean, ranging from Southern California down through the Gulf of California and along the coast of Mexico to Peru.
Description
A charming, diminutive bivalve with a distinct wedge shape, rounded anterior, and truncated posterior. The surface is smooth due to wave action, exhibiting a glossy texture that accentuates the dramatic violet and white coloration. The margins are tightly closed with a sturdy hinge structure characteristic of active burrowers.
Key Features
Wedge-shaped profile, asymmetrical valves, smooth eroded exterior, and a rich purple or violet coloration concentrated near the umbo or posterior region.
Collector Value
Low to moderate commercial value, but highly valued by casual beachcombers and shell crafters for their vibrant colors and cute size. Usually collected in handfuls rather than individually purchased.
Condition Notes
Good to Fine condition for a beach find. The shell is fully intact with no major fractures, though it shows natural smoothing and minor wear from tumbling in the surf, typical of beach-collected specimens.
Interesting Facts
Bean clams are famous for their mass migrations up and down the intertidal zone with the tides, using their muscular foot to burrow rapidly into the sand before a wave can wash them away.
Ecological Role
Serves as a crucial food source for shorebirds, fish, and crabs. As filter feeders, they help clear suspended organic matter from the surf zone, playing an important role in coastal water quality.
Similar Species
Donax variabilis (Coquina clam found in the Atlantic, which tends to have more varied radial ray patterns and brighter rainbow colors).
Beach Finding Tips
Look along sandy beaches in the swash zone just as the wave recedes. Watch for tiny jets of water or quick movements in the sand as they re-bury themselves.
Notes
Hukilau