Purple Clam (also known as Amethyst Clam or Purple Mahogany Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Tellinidae, Genus: Macoma, Species: Macoma nasuta · Tellinidae (Tellin family) · Bivalve, whole shell, oval to rounded-triangular shape
Species
Macoma nasuta
Shell Type
Bivalve, whole shell, oval to rounded-triangular shape
Family
Tellinidae (Tellin family)
Size
Approximately 1.5 to 2 inches in length, which is average for this species. Adults typically range between 1 and 2.5 inches.
Color & Pattern
Subtle soft lavender, pale purple, and greyish-white tones with concentric growth lines. The interior often features a richer purple or chalky white coloration. The colors are natural and softly weathered.
Rarity
Common
Habitat
Marine, typically found burrowed in soft substrates such as mud, fine sand, and muddy-sand bays, estuaries, and protected intertidal to shallow subtidal zones.
Geographic Range
Eastern Pacific Ocean, ranging from Kodiak Island, Alaska down to San Bueneventura, California.
Description
A charming and smooth bivalve shell characterized by its distinct rounded oval outline and subtle purplish-gray hues. The surface exhibits delicate concentric growth lines with a slightly chalky texture. The posterior end is characteristically bent slightly to one side, a functional adaptation for its burrowing lifestyle.
Key Features
Smooth concentric growth rings, soft purple and white coloration, and a noticeable lateral twist or flex at the posterior end.
Collector Value
Low to moderate commercial value, frequently collected by beachcombers and local enthusiasts rather than specialized high-end shell collectors.
Condition Notes
Good condition, intact single valve with minor natural weathering and soft discoloration typical of beach-worn specimens. Collectibility grade is Good.
Interesting Facts
Macoma clams are notable for having separate inhalant and exhalant siphons that operate independently. The inhalant siphon acts like a vacuum cleaner, roving across the sediment surface to suck up detritus and microalgae.
Ecological Role
Serves as an important prey item for shorebirds, bottom-feeding fish, and crabs. As deposit feeders, they help recycle nutrients within intertidal mudflat ecosystems.
Similar Species
Other Tellinidae family members such as the Bent-nosed Macoma or Bodega Tellin, which can be distinguished by subtle differences in shell proportions and the degree of the posterior twist.
Beach Finding Tips
Best found by beachcombing along protected mudflats or sandy-mud bays at low tide, or by gently sifting through wet sand near estuary outflows.