Obese Nutmeg Shell, Cancellaria obesa

Obese Nutmeg Shell, Cancellaria obesa. Shell collected off the beach of Punta Chivato, Baja California Sur, June 2025. Size: 4.4 cm (1.7 inches) x 2.7 cm (1.1 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Obese Nutmeg Shell, Cancellaria obesa. Shell collected off the beach of Punta Chivato, Baja California Sur, June 2025. Size: 5.2 cm (2.0 inches) x 3.0 cm (1.2 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Phylogeny: The Obese Nutmeg Shell, Cancellaria obesa (G.B. Sowerby I, 1832), is a gastropod mollusk that is a member of the Cancellariidae Family of Nutmeg Shells. The Cancellaria Genus is one of thirty-eight genera in the Cancellariidae Family, and there are thirty-five species in the Cancellaria Genus. They are also known as the Fat Nutmeg Shell and the Stout Nutmeg Shell and in Mexico as Cancellaria Gorda and Nuez Moscado Obesa.

Description: Obese Nutmeg Shells consist of six or seven whorls with a moderately high spire.  The body whorl is large, solid, and globose. The shoulders are slightly flattened and the sutures are well marked, though many specimens are worn and rounded. The exterior is sculpted with strong spiral ribs and fine axial lines.  These ribs carry though to the inside of the outer lip of the aperture. The inner lip of the aperture is callused and sculpted with two strong folds. The aperture is fairly large and elongate, with an open canal at both ends. The exterior of these shells is whitish with broad brown bands, and the interior is white. The living animal is cream colored with orange-brown mottling. Obese Nutmeg Shells  reach a maximum of 6.5 cm (2.5 inches) in length.

Habitat and Distribution: Obese Nutmeg Shells are found on sand from the intertidal zone to depths of around 90 m (295 feet). Obese Nutmeg shells 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.

Ecology and Behavior:  Little is known about the specific diet of Obese Nutmegs. They are suctorial feeders that feed on the body fluids of other animals. Other species in the family prey on rays, polychaetes, crustaceans, and other mollusks. Obese Nutmegs are preyed upon by shore birds, crabs, sea stars, and other gastropods. Obese Nutmeg Shells are gonochoric and reproduce sexually, with internal fertilization. The eggs are laid in protective capsules. Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Obese Nutmeg has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Cancellaria acuminata and Cancellaria eburnaeformis.