Nutting's Cockle (also known as the Spiny Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Trachycardium, Species: Trachycardium procerum · Cardiidae (Cockle family) · Bivalve (two-shelled), whole shell valve, fan/rounded shape
Species
Trachycardium procerum
Shell Type
Bivalve (two-shelled), whole shell valve, fan/rounded shape
Family
Cardiidae (Cockle family)
Size
Approximately 1 to 1.5 inches, which is on the smaller to average side for this species. Adults typically range from 1 to 2.5 inches.
Color & Pattern
Off-white to cream base coloration with characteristic reddish-brown or purple-pink patches inside the interior cavity (particularly near the umbo and muscle scars). The exterior features strong radial ribs with interlocking marginal teeth.
Rarity
Common to Uncommon, frequently found by beachcombers and divers along the coast of Southern California and the Gulf of California.
Habitat
Found in shallow subtidal waters down to moderate depths, residing primarily in sandy or muddy sand substrates in marine environments.
Geographic Range
Eastern Pacific Ocean, ranging from Southern California (including San Diego) down through the Gulf of California and along the coast of Central and South America to Peru.
Description
This sturdy, rounded bivalve shell displays strong, prominent radial ribs radiating from the umbo. The margin is deeply crenulated with interlocking teeth that fit tightly with the opposite valve when living. The interior is smooth with distinct muscle attachment scars and a warm, brownish-pink flush near the center.
Key Features
Robust, heart-shaped profile when viewed laterally, prominent radial ribs with distinct sculptural nodes or scales, and deeply crenulated margins.
Collector Value
Low to moderate value. Commonly collected by beachcombers in its native range, making it a popular educational and beginner-to-intermediate collection piece rather than a high-end specialty item.
Condition Notes
Good condition. Shows some natural wear and sun-bleaching typical of beach-worn specimens, but the structural integrity and internal coloration remain well-preserved. Grade: Good.
Interesting Facts
Cockles are capable of a unique leaping locomotion using their muscular, sickle-shaped foot to escape predators like carnivorous snails and starfish.
Ecological Role
Cockles act as important benthic filter feeders, helping to clear water columns of phytoplankton and serving as a crucial food source for various marine fish, rays, and shorebirds.
Similar Species
Megapitaria squalida (Chocolate Clam) or other Pacific cockle species like Dallocardia senticosa, which can be distinguished by different rib counts, shapes, and hinge structures.
Beach Finding Tips
Look along sandy beaches in Southern California, particularly after winter storms or high tides, by scanning the high tide line where shell debris accumulates.
Notes
San Diego