White-spined Thorny Oyster Shell, Spondylus leucacanthus
White-spined Thorny Oyster Shell, Spondylus leucacanthus. Shell provided by the commercial fishermen of the greater Los Cabos area, March 2014. Size: 6.6 cm (2.6 inches) x 6.6 cm (2.6 inches).
White-spined Thorny Oyster Shell, Spondylus leucacanthus. Shell collected off the beach at Punta Chivato, Baja California Sur, May 2024. Size: 9.0 cm (3.5 inches) x 9.6 cm (3.8 inches) x 3.6 cm (1.4 inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
White-spined Thorny Oyster Shell, Spondylus leucacanthus. Shell collected off the beach at Punta Chivato, Baja California Sur, May 2024. Size: 6.0 cm (2.4 inches) x 6.2 cm (2.4 inches) x 4.4 cm (1.7 inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
Phylogeny: The White-spined Thorny Oyster, Spondylus leucacanthus (Broderip, 1833), is a bivalve mollusk that is a member of the Spondylidae Family of Spiny Oyster Shells. The Spondylus Genus is the only genus in the Spondylidae Family, and there are seventy-five species in the Spondylus Genus. They are also known as the Spiny Oyster Shell and the Thorny Oyster Shell in Mexico as Ostra Espinosa and Ostra Espinosa del Pacifico.
Description: White-spined Thorny Oyster Shells have a round outline with a straight hinge and small ears or wings on both sides of the hinge. The are inflated and inequivalve, with the right valve slightly more convex. The exterior of this exquisite shell is decorated with long, beautiful delicate spines that can be up 8 cm (3.1 inches) in length. The exterior may be white, yellow, coral, orange, or brown. The interior is white with a color band, usually only near the hinge, that matches the outside color. Not including the spines, White-spined Oyster Shells reach a maximum of 15.6 cm (6.1 inches) in length and 15.6 cm (6.1 inches) in height. Spiny Oyster Shells can be confused with the similar looking Donkey Thorn Oyster Shell, Spondylus limbatus and Pacific Thorny Oyster Shell, Spondylus crassisquama (both with more spathate [spatula-like] spines and a color band that usually extends around the interior margin).
Habitat and Distribution: White-spined Thorny Oysters are generally free living on sand but some may be found with attachment to rocks. They live at depths between 10 m (35 feet) and 91 m (300 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent from north of Cedros Island, Baja California along the central and northwest coasts of the Baja Peninsula and from north of Bahía de los Ángeles, Baja California, in the Sea of Cortez.
Ecology and Behavior: White-spined Thorny Oysters are suspension feeders that feed primarily on planktonic algae and suspended organic matter. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. Spiny Oysters host other species as epibionts, including sponges and bryozoans. Most of these relationships appear to be either commensal or symbiotic, with the epibionts getting a safe place to live, while camouflaging the host. From a conservation perspective they have not been formally evaluated, although related species are considered Threatened in the Eastern Pacific. White-spined Thorny Oysters have occasionally been fished commercially for their edible adductor muscle and their shell. This has resulted in overfishing in localized areas.
Synonyms: Spondylus leucacantha and Spondylus ursipes.