Pacific Littleneck Clam (also known as Rock Cockle or Steamer Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Veneridae, Genus: Leukoma, Species: L. staminea · Veneridae (Venus Clam family) · Bivalve (two-shelled); this specimen is a single valve. Shape is oval to sub-quadrate with prominent radiating ribs.
Species
Leukoma staminea
Shell Type
Bivalve (two-shelled); this specimen is a single valve. Shape is oval to sub-quadrate with prominent radiating ribs.
Family
Veneridae (Venus Clam family)
Size
Approximately 1.25 inches (32mm) in length. This is a juvenile to sub-adult specimen; adults typically reach 2 to 3 inches.
Color & Pattern
Base color is off-white to yellowish-tan with subtle brownish geometric patterns or chevrons. The specimen shows faint concentric growth lines intersecting with strong radial ribs, creating a latticed texture. The interior is likely white or polished cream.
Rarity
Very Common. This species is one of the most frequently encountered bivalves on Northern California beaches and mudflats.
Habitat
Intertidal and shallow subtidal zones. Prefers being buried 3-8 inches deep in packed mud, sand, or gravelly substrates, often under rocks.
Geographic Range
Eastern Pacific Ocean, ranging from the Aleutian Islands, Alaska, down to Baja California, Mexico. Very common in the San Francisco Bay Area.
Description
An elegant example of a North Pacific Venus clam. The shell is sturdy and inflated with a distinct sculpture of fine radial ribs and less prominent concentric ridges. The margin is finely crenulated (zigzagged) on the inside, which matches the external ribbing. Its oval shape and robust hinge make it a classic representative of the San Francisco Bay intertidal fauna.
Key Features
Strong radial ribs that are more prominent than the concentric growth lines; oval shape with an anteriorly directed umbo (beak); finely serrated inner shell margin.
Collector Value
Low monetary value due to its abundance, but high educational value for regional collections. It is a staple specimen for anyone documenting the biodiversity of the California coast.
Condition Notes
Good condition. The exterior sculpture is well-preserved with minimal beach-wear. However, as a single valve that appears slightly sun-bleached, it is a standard field find rather than a museum-grade specimen.
Interesting Facts
This species is a popular edible clam and was a significant food source for Indigenous peoples along the Pacific coast for millennia. Unlike some clams that can burrow deep, the Littleneck stays relatively close to the surface, making it prey for sea stars, moon snails, and shorebirds.
Ecological Role
Suspension feeder that filters plankton and organic detritus from the water column. They play a vital role in water filtration and serve as a primary prey item for many marine organisms. The species is subject to state fishing regulations regarding size and bag limits.
Similar Species
Nutall's Cockle (Clinocardium nuttallii) which has much larger, deeper ribs; Manila Clam (Venerupis philippinarum) which is more elongated and often has bolder purple staining on the interior.
Beach Finding Tips
Search in the San Francisco Bay or along the coast during low tide. Look for 'wash' lines after a storm or dig slightly into gravelly sand near the low-tide mark. They are often found where the sediment is firm rather than soft mud.
Notes
SF Bay Area, NorCal