Pacific Coast Egg Cockle Shell, Laevicardium substriatum
Pacific Coast Egg Cockle Shell, Laevicardium substriatum. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2025. Size: 3.0 cm (1.2 inches) x 3.0 cm (1.2 inches) x 0.9 cm (0.4 inches). Collection, photographs and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
Phylogeny: The Pacific Coast Egg Cockle Shell, Laevicardium substriatumm (Conrad 1837), is a bivalve mollusk in the Cardiidae Family of Cockles and True Cockle Shells and the Laevicardiinae Subfamily. The Laevicardium Genus is one of two genera in that subfamily and there are eighteen species in the Laevicardium Genus.
Description: Pacific Coast Egg Cockle Shells are ovate to trigonal in outline and well inflated in profile. The posterior may be longer than the anterior. Both ends are rounded to broadly rounded. These shell are of thin construction. The umbones are pronounced. Pacific Coast Egg Cockle Shells are sculpted with around forty fine radial ribs. Sometimes these ribs are only visible at the anterior margin or on the shell’s interior. The exterior may be yellowish or gray, with brown specks or blotches. The interior is whitish with varying amounts of pinkish, salmon, purplish, or brown mottling. The periostracum is thin, shiny, and tan in color. Pacific Coast Egg Cockle Shells reach a maximum of 3.0 cm (1.2 inches) in length.
Habitat and Distribution: Pacific Coast Egg Cockles are found in mud or sand, intertidally, and to depths up to 160 m (525 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean.
Ecology and Behavior: Pacific Coast Egg Cockles are suspension feeders that feed primarily on plankton and other suspended organic matter. They are eaten by fish, shore birds, sea stars, crabs, and gastropods. They are simultaneous hermaphrodites (having both male and female reproductive organs) and reproduce sexually, through broadcast spawning, with external fertilization. Embryos develop into free-swimming trochophore larvae, followed by a veliger stage, before settling on the sea floor. Their engagement in any type of parasitic, commensal or mutualistic relationships has not been formally documented. From a conservation perspective Pacific Coast Egg Cockle Shells have not been formally evaluated however, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.
Synonyms: Cardium cruentatum and Cardium substratum.