Slight Baby Ear Shell, Sinum debile

Slight Baby Ear Shell, Sinum debile. Shell courtesy of the commercial fishermen of the greater Los Cabos area, Baja California Sur, October 2009. Size: 2.6 cm (1.0 inch) x 1.9 cm (0.75 inches).

Phylogeny: The Slight Baby Ear Shell, Sinum debile (Gould, 1853), is a gastropod mollusk that is a member of the Naticidae Family of Moon Shells. The genus Sinum is one of thirty-eight genera in this family, and there are twenty-seven species in this genus. They are also known as the Frail Ear Shell.

Description: Slight Baby Ear Shells have a flattened Moon Snail shell appearance. When viewed from the base, they resemble a human ear. They are thin, have a large body whorl, and a very low spire. The aperture is large, round, and smooth. The shell is sculpted with fine lines running along and across the whorls. The exterior of the shell is white with a light blue or light rust tinge. Smaller specimens have a translucent shell. The interior is white, with some of the exterior color showing through. Slight Baby Ear Shells reach a maximum of 3.1 cm (1.2 inches) in length and 2.3 cm (0.9 inches) in height.

Habitat and Distribution: Slight Baby Ears are found in mud and sand substrates, in the intertidal zone and to depths up to 250 m (820 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 have not been documented along the west coast of the Baja Peninsula and from north of Santa Rosalia, Baja California Sur, in the Sea of Cortez.

Ecology and Behavior:  Slight Baby Ears are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in the Naticidae Family are predators that feed primarily on bivalves and gastropods, including other moon shells. They are eaten by rays, including the Giant Electric Ray, Narcine entemedor. They are gonochoric and reproduce sexually. Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Slight Baby Ear 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: Sigaretus debilis, Sinum (Sinum) debile, and Sinum pazianum.