Pacific Littleneck Clam, Common Pacific Littleneck, Rock Cockle (Protothaca staminea)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Veneridae, Genus: Protothaca, Species: Protothaca staminea · Veneridae (Venus Clam family) · Bivalve, whole single valve, oval to rounded-subquadrate shape
Species
Protothaca staminea
Shell Type
Bivalve, whole single valve, oval to rounded-subquadrate shape
Family
Veneridae (Venus Clam family)
Size
Approximately 2 inches in length, which is a moderate, typical size for this species. Adults generally range from 1.5 to 2.5 inches.
Color & Pattern
Brownish-tan exterior base color with subtle concentric growth lines and faint radiating ribs giving a checkered appearance under close inspection. The umbo shows some wear, revealing a lighter tone. The colors appear natural but weathered from marine exposure.
Rarity
Very Common
Habitat
Found in intertidal and shallow subtidal zones, typically buried a few inches deep in gravel, mud, sand, or mixed substrates, often near protected bays and estuaries.
Geographic Range
Northeastern Pacific Ocean, ranging from the Aleutian Islands, Alaska, down to Baja California, Mexico.
Description
A sturdy, solid bivalve shell with a rounded to oval contour. The exterior surface features a combination of prominent concentric ridges and fine radial ribs, creating a distinct grid-like or reticulated texture. The umbo is moderately prominent and anteriorly directed.
Key Features
Strong reticulated sculpture formed by the intersection of prominent concentric growth lines and fine radial ribbing; oval-to-rounded outline; sturdy calcified valve structure.
Collector Value
Low commercial or collector value due to extreme commonness, though heavily appreciated by beachcombers and local foragers as a kitchen keepsake or crafting material. Valued typically at a few cents to a dollar.
Condition Notes
Single valve in Fair condition. Exhibits several notable predator or boring sponge drill holes near the umbo and mid-body. Surface shows minor weathering and loss of pristine luster, but the structural integrity of the valve remains intact.
Interesting Facts
Protothaca staminea is a popular edible clam heavily harvested in commercial and recreational fisheries along the Pacific Northwest. They can siphon water and feed efficiently while buried completely beneath the substrate.
Ecological Role
Serves as an important prey item for shorebirds, sea otters, crabs, and bottom-feeding fish. As a filter feeder, it helps clean coastal waters by consuming microscopic algae and organic particulates.
Similar Species
Manila clam (Venerupis philippinarum), which is oblong rather than rounded and has deeper radiating grooves; butter clam (Saxidomus gigantea), which lacks the prominent radial ribs.
Beach Finding Tips
Look along rocky and gravelly Pacific Northwest beaches during extreme low tides, particularly near protected coves or estuaries where sediment accumulates.