Pismo Clam (Alternate name: Thin Pismo Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Veneridae, Genus: Tivela, Species: Tivela stultorum · Veneridae (Venus Clam family) · Bivalve (two-shelled clam), whole shell fragment showing distinctive wedge shape
Species
Tivela stultorum
Shell Type
Bivalve (two-shelled clam), whole shell fragment showing distinctive wedge shape
Family
Veneridae (Venus Clam family)
Size
Approximately 3.5 inches in length. Adults typically range from 4 to 7 inches, so this specimen is a medium-sized or slightly juvenile individual.
Color & Pattern
Cream to yellowish-tan base color with distinct brownish-purple or reddish-brown concentric bands and rays. The colors are natural with slight sun-bleaching along the raised growth ridges.
Rarity
Common in its native range, though intact large specimens are less frequently found washed ashore due to harvesting restrictions and natural burial depth.
Habitat
Found buried in the sand of high-energy, open surf-swept sandy beaches in the shallow subtidal and intertidal zones, from the low tide line down to about 25 feet deep.
Geographic Range
Eastern Pacific coast of North America, ranging from Half Moon Bay, California, down to Baja California, Mexico.
Description
A sturdy, heavy, equilateral triangular to wedge-shaped bivalve shell with smooth, polished exterior surfaces marked by concentric growth lines and characteristic colorful bands. The margins are solid and smooth without crenulations.
Key Features
Heavy, thick wedge shape, smooth glossy texture (when fresh), strong internal hinge with robust teeth, and distinct concentric color banding radiating from the umbo.
Collector Value
Low to moderate commercial value. Common in shell shops along the West Coast of the US, prized more for local sentimental value and beachcombing nostalgia than high monetary worth.
Condition Notes
Good condition overall, showing minor wear and weathering along the edges with some fading of the original glossy periostracum. No major structural fractures.
Interesting Facts
The Pismo Clam is famous in California history and was once so abundant that people gathered them using horses and plows. They are filter feeders and can live up to 20 years.
Ecological Role
Serves as an important food source for sea otters, rays, shorebirds, and humans. Filters large volumes of seawater, contributing to coastal water clarity.
Similar Species
Chione clams and other venus clams, but distinguished by the distinct heavy triangular wedge shape and glossy, smooth surface lacking deep radial ribs.
Beach Finding Tips
Look along exposed southern California sandy beaches at extremely low tides, especially after winter storms. Search for the siphon holes or 'shows' in the sand.