Pacific Little Cockle (also known as the Spiny Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Clinocardium, Species: Clinocardium nuttallii · Cardiidae (Cockle family) · Bivalve (two-shelled), whole shell, fan or heart-shaped when viewed from the side
Species
Clinocardium nuttallii
Shell Type
Bivalve (two-shelled), whole shell, fan or heart-shaped when viewed from the side
Family
Cardiidae (Cockle family)
Size
Approximately 1 inch in length and width, which is on the smaller side for this species. Adults typically range from 1.5 to 4 inches.
Color & Pattern
Off-white to pale cream base color with faint brownish-tan mottling near the umbo and along the radial ribs. The colors appear somewhat sun-bleached and weathered from wave action. The interior is white with a glossy finish.
Rarity
Common
Habitat
Found in shallow marine waters, typically living buried just beneath the surface in intertidal and subtidal mudflats, sandy bays, and quiet protected coastal waters.
Geographic Range
Eastern Pacific Ocean, ranging from the Aleutian Islands in Alaska down to San Diego, California, and northern Baja California.
Description
A charming, robust bivalve shell featuring prominent, rounded radial ribs that interlock at the margin. The exterior showcases strong ridges running from the umbo to the ventral edge, creating a scalloped profile. The shell is heart-shaped in cross-section and possesses a solid, durable structure adapted for life in shifting coastal sediments.
Key Features
Distinguished by its numerous (typically 30 to 37) prominent, rounded radial ribs, asymmetric heart-shaped profile, and distinctive serrated margins where the ribs meet at the edge.
Collector Value
Low to moderate commercial value. While very popular among casual beachcombers and beginner shell collectors, pristine large specimens hold more value than weathered single valves like this one.
Condition Notes
The specimen is a whole, single valve in fair-to-good condition. It shows moderate wear along the margins and slight sun-bleaching, with loss of the original vibrant brown patterning, but retains its structural integrity and sculptural ribs.
Interesting Facts
Cockles are capable of remarkable locomotion; using a strong, muscular, hatchet-shaped foot, they can leap, dig themselves rapidly back into the sand if exposed, or even 'jump' to escape predators like starfish.
Ecological Role
As suspension feeders, cockles filter phytoplankton and organic particles from the water column, helping to maintain water clarity. They serve as an important food source for shorebirds, fish, sea otters, and crabs.
Similar Species
Trachycardium species (such as the Egg Cockle) or Chione clams. They can be differentiated by the specific number of radial ribs and the symmetry of the hinge plate.
Beach Finding Tips
Best found by beachcombing along protected sandy bays, mudflats, and estuaries during low tide, particularly after winter storms or heavy wave action which washes buried shells ashore.
Notes
San Diego