Spondylopsis Kitten’s Paw Shell, Plicatula spondylopsis
Spondylopsis Kitten’s Paw Shell, Plicatula spondylopsis. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2026. Size: 2.7 cm (1.1 inches) x 1.9 cm (0.7 inches) x 0.8 cm (0.3 inches). Photograph and Identifications courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
Spondylopsis Kitten’s Paw Shell, Plicatula spondylopsis. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2026. Size: 2.9 cm (1.1 inches) x 2.6 cm (1.0 inches) x 0.9 cm (0.3 inches). Photograph and Identifications courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
Phylogeny: The Spondylopsis Kitten’s Paw Shell, Plicatula spondylopsis (Rochebrune, 1895) is a member of the Plicatulidae Family of Kitten Paw Shells. The Plicatula Genus is the only genus in the Plicatulidae Family and there are seventeen species in the Plicatula Genus.
Description: Spondylopsis Kitten’s Paw Shells have an irregular trigonal to ovate outline and a compressed profile. The right valve attaches to the substrate which leaves a flattened scar on the shell’s exterior. These shells are sculpted with a variable number of weak to strong radial ribs, which form crenulations on the inner shell margins. Some specimens have tubular spines, especially at the margins. The exterior is reddish-brown. The interior is whitish with brown around the margin. The margin is usually marked with darker, fine, radial, lines. Specimens that attach to flat surfaces tend to be thinner-shelled and have less strong ribs. Spondylopsis Kitten’s Paw Shells reach a maximum of 5.0 cm (1.9 inches) in diameter. This species is similar in appearance to the Gibbose Kitten’s Paw Shell, Plictula gibbosa, of the Western Atlantic.
Habitat and Distribution: Spondylopsis Kitten’s Paw Shells are found attached to rocks and other hard surfaces. They live in the intertidal zone and to depths up to 80 m (262 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 the west coast of the Baja Peninsula.
Ecology and Behavior: Spondylopsis Kitten’s Paw Shells are suspension feeders that feed primarily on planktonic algae and suspended organic matter. They are preyed upon by crabs, fish, gastropods, and sea stars. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. Their engagement in any type of commensal, parasitic, or mutualistic relationship has not been formally documented. From a conservation perspective Spondylopsis Kitten’s Paw Shells have not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.
Synonyms: Plicatula inezana