Spiny Cup-and-Saucer Shell, Crucibulum spinosum

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 2.8 cm (1.1 inches) x 1.4 cm (0.6 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato. Beautiful shell with almost smooth texture that has very short spines along the spiraling rays.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, May 2011. Size: 3.0 cm (1.2 inches) x 2.6 cm (1.0 inch).

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, May 2011. Size: 3.1 cm (1.2 inches) x 2.4 cm (0.9 inches) x 0.9  cm (0.4 inches).

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 3.3 cm (1.3 inches) x 2.8 cm (1.1 inches) x 1.3 cm (0.5 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato. Shell with more developed spines along the the spiraling rays.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach of Punta Chivato, Baja California Sur, April 2025. Size: 3.4 cm (1.3 inches) x 2.9 cm (1.1 inches) x 1.0 cm (0.4 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 5.3 cm (2.1 inches) x 4.5 cm (1.8 inches) x 1.6 cm (0.6 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shells collected off the beach of Punta Chivato, Baja California Sur, March 2025. Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.  A series of shells with smooth surfaces without spines that display the spiral wave like wrinkles and small ribs.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shells collected off the beach of Punta Chivato, Baja California Sur, March 2025. Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.  A series of shells that retain the spiral composition but possess small nodular spines.

Spiny Cup-and-Saucer Shell, Crucibulum spinosum. Shells collected off the beach of Punta Chivato, Baja California Sur, March 2025. Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.  A series of shells that demonstrates the progression, from left to right, of a completely smooth shell to a spined shell all of which have a rayed pattern throughout.

Phylogeny: The Spiny Cup-and-Saucer Shell, Crucibulum spinosum (G. B. Sowerby, 1824), is a member of the Calyptraeidae Family of Cup-and-Saucer and Slipper Limpet Shells. The genus Crucibulum is one of eleven genera in this family, and there are nineteen species in this genus.

Description: Spiny Cup-and-Saucer Shells have a circular outline with a central, recurved, apex. The exterior of the shell is sculpted with wavy, radiating ridges that are studded with spines that vary in length varies between individual shells. Some of the spines become tubular in shape. The shell may be yellowish white, tan, orange-brown, dark brown or gray, often with brown specks, or brownish rays or purplish rays. The interior cup is white, and flattened on one side. Spiny-Cup-and-Saucer Shells reach a maximum of 7.1 cm (2.8 inches) in length.

Habitat and Distribution: Spiny Cup-and-Saucers are found attached to rocks, rubble, and shells in the intertidal zone, and to depths up to 90 m (295 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean. They have been recently introduced in Hawaii.

Ecology and Behavior: Spiny Cup-and-Saucers are both suspension feeders that filter plankton from the water with their gills and grazers that eat algae and detritus.  They are protandrous hermaphrodites, meaning they change sex from male to female during their lives. They reproduce sexually, with internal fertilization. The eggs are brooded in sacs, under the shell. Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Spiny Cup-and-Saucers has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms:  Calyptraea (Calypeopsis) tubifera, Calyptraea cinerea, Calyptraea hispida, Calyptraea spinosa, and Patella peziza.