Tivela, Pacific Pismo Clam, Chocolate Clam
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Veneridae, Genus: Megapitacia, Species: squalida · Veneridae (Venus Clam family) · Bivalve (two-shelled). This specimen is a single valve with a triangular to rounded-oval shape.
Species
Megapitacia squalida (formerly Macrocallista squalida)
Shell Type
Bivalve (two-shelled). This specimen is a single valve with a triangular to rounded-oval shape.
Family
Veneridae (Venus Clam family)
Size
Approximately 2 to 2.5 inches. This is a juvenile to sub-adult specimen; adults can grow up to 4-5 inches.
Color & Pattern
Glossy cream-yellow base with distinct radial bands of tan and light brown. Concentric growth lines are visible. The shell possesses a naturally high-luster, polished appearance characteristic of 'Veneridae' clams.
Rarity
Common. This is one of the most frequently encountered shells on the beaches around Cabo and the Sea of Cortez.
Habitat
Burrows in sandy substrates in shallow subtidal zones, typically from the low tide mark down to 100 feet deep.
Geographic Range
Eastern Pacific, specifically from Baja California (Cabo San Lucas) south to Peru. It is very common in the Gulf of California.
Description
A sturdy, smooth-surfaced bivalve with a glossy, porcelain-like finish. The shell is thick and inflated, showing a prominent umbo (beak) that curves slightly forward. The exterior is decorated with subtle concentric rings and darker radial streaks that diffuse toward the margins.
Key Features
Triangular-ovate shape, high-gloss finish without artificial polishing, and the characteristic radial brown 'stains' or stripes on a yellowish background.
Collector Value
Low to Moderate. While beautiful, they are very common. It is a staple for hobbyist collectors visiting Cabo, but only 'Gem' quality paired valves hold significant trade value.
Condition Notes
Good condition. The margins appear slightly worn (beached), and there is some minor sun-bleaching, but the characteristic gloss and banding remain visible. Collectibility grade: Fine.
Interesting Facts
Locally known in Mexico as 'Almeja Chocolata' due to the deep brown color of the shells in adult specimens. They are a significant food source in the Baja region and are famously used in 'Almejas tatemadas' (buried roasted clams).
Ecological Role
Suspension feeders that filter phytoplankton from the water column. They serve as a primary food source for sea stars, rays, and shorebirds. The species is managed in Mexico to prevent overfishing.
Similar Species
Tivela stultorum (Pismo Clam) which is more elongated, and Callista chione (Smooth Venus) found in the Mediterranean.
Beach Finding Tips
Look along the high tide line after a storm or strong surf in the Cabo San Lucas area. They are often found half-buried in the sand near rocky outcrops.
Notes
Cabo