Little Deer Cowry Mollusk, Macrocypraea cervinetta

Little Deer Cowry Mollusk, Macrocypraea cervinetta. Underwater photographs taken in Zihuantanejo Bay, Guerrero, January 2020. Photographs and identifications courtesy of Ron Woheau, Zihuantanejo.

Note:  You can find the Little Deer Cowry Shell presented in our sister website as the Little Deer Cowry Shell, Macrocypraea cervinetta, along with a writeup of the parent Cypraeidae Family of Cowry Shells.

Phylogeny: The Little Deer Cowry, Macrocypraea cervinetta (Kiener, 1843), is a gastropod mollusk in the Cypraeidae Family of Cowry Shells.  They are in the subfamily Cypraeinae and the tribe Mauritiini. The Macrocypraea Genus is one of fifty-five genera in the Cypraeidae Family, and there are four species in the Macrocypraea Genus.  There are two currently recognized subspecies for this species – Macrocypraea cervinetta californica (primarily in Sea of Cortez) and Macrocypraea cervinetta cervinetta (central and southern Mexico to Peru). The Little Deer Cowry Shell is virtually identical to the Measled Cowry Shell, Macrocypraea zebra (Linnaeus, 1758) that is a resident of the Atlantic Ocean. It is thought that the two are common ancestors appearing before the country of Panama surfaced separating the two oceans approximately three million years ago. The genus name Macrocypraea comes from the Greek word meaning “large cowry”. The species name cervinetta comes from the Latin word for “little deer”. The common name refers to the spotted shell’s resemblance to a spotted fawn. They are also known as the Panamic Deer Cowry Shell and in Mexico as Ciprea Ciervo and Cuarí Cervatillo.

Morphology: The Little Deer Cowry has a  large retractable mantle that can cover the entire shell. The mantle is gray to black in color and covered with numerous translucent papillae. The shell has an elongated egg-shape, with a strongly toothed aperture. The dorsal surface may be yellowish-brown, brown, or dark mahogany, and covered with round white spots. The spots may transition into rings along the sides. Most shells have three or four purplish brown bands across the dorsal surface, and a lighter colored longitudinal band. Ventrally, they are violet-brown in color. The juveniles lack spotting on the shell and teeth along the aperture. The Little Deer Cowry Shell is the largest cowry in the area reaching a maximum of 11.0 cm (4.3 inches) in length and 5.5 cm (2.2 inches) in height.

Habitat and Distribution: Little Deer Cowries are found under rocks, within rock crevices, and on rubble in the intertidal zone and to depths up to 24 m (80 feet). They are a subtropical to tropical Eastern Pacific species. They are found in all Mexican waters of the Pacific Ocean with the exception that the are absent from the west coast of the Baja Peninsula.

Diet: Little Deer Cowries are omnivorous grazers that feed primarily on algae and small encrusting invertebrates.

Predation:  There is little documentation of predation of Little Deer Cowries. It is thought that they a prey for octopuses and fishes. They as most vulnerable as juveniles, when they are also prey for crabs.

Reproduction: Little Deer Cowries are gonochoric (male or female for life) and reproduce sexually, with internal fertilization. The female lays her eggs as gelatinous capsules attached to hard substrate. The female broods the egg mass by enveloping it with her foot for protection. The embryos hatch as free-swimming planktonic veliger larvae. After two weeks to several months, depending on environment conditions, the larvae metamorphose into benthic juveniles.

Ecosystem Interactions: The engagement of Little Deer Cowries in any type of commensal, parasitic, or symbiotic relationship has not been formally documented.

Human Interactions:  Little Deer Cowries are occasionally the target of shell collectors. Otherwise, they have no significant impact on human activities. From a conservation perspective they have not been formally evaluated however they are common with a fairly wide distribution and should be consider to be of Least Concern.

Synonyms: Cypraea cervinnetta.