Olive Turban Shell, Uvanilla olivacea

Olive Turban Shell, Uvanilla olivacea. Size: 2.7 cm (1.1 inches) x 1.4 cm (0.6 inches). Shell collected off the beach in the greater Los Cabos area, Baja California Sur, April 2017.

Olive Turban Shell, Uvanilla olivacea. Size: 2.6 cm (1.0 inches) x 1.3 cm (0.5 inches). Shell collected off the beach at Las Barilles, Baja California Sur, February 2023. Size: 5.6 cm (3.8 inches) x 3.2 cm (1.3 inches) in height. Collection courtesy of Mack and Becky Fonteno, Las Barilles, Baja California Sur.  Photographs and identifications courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Phylogeny: The Olive Turban, Uvanilla olivacea (W. Wood, 1828), is a gastropod mollusk that is a member of the Turbinidae Family of Turban Shells. The genus Uvanilla is one of eighteen genera in this family, and there are four species in this genus. They are also known as the Blood Spotted Star Shell.

Description: Olive Turban shells are cone shaped, rugged, and strong. They are almost as tall as they are wide. They consist of six or seven whorls, with the bottom whorl being more rounded. The exterior is sculpted with fine diagonal lines. The shell is olive or brownish green in color.  There is a spiral rib on the base.  The center of the base is marked with a brilliant reddish orange spot in the umbilical pit with a dark brown or black border. The aperture is pearly white. Most shells have a fibrous periostracum. Olive Turban Shells reach a maximum of 6.5 cm (2.6 inches) in diameter.

Habitat and Distribution: Olive Turbans are found clinging to rocks in the intertidal zone, and to depths up to 20 m (65 feet). They are a tropical Eastern Pacific species that are found in Mexican waters of the Pacific Ocean from La Paz, Baja California Sur south to Guatemala. They have not been documented from the  west coast of the Baja peninsula, though there are anecdotal reports of them being found south of Magdalena Bay, Baja California Sur.

Ecology and Behavior: Olive Turbans are herbivorous grazers that feed primarily on algae and detritus. They are gonochoric and reproduce sexually,  with external fertilization. The eggs are laid as a gelatinous mass. There is no mention in the available literature of them engaging in any types of parasitic, commensal, or symbiotic relationships. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms:  Astraea olivacea, Trochus (Calcar) erythropthalmus, Trochus (Calcar) melchersi, Trochus brevispinosus, Trochus erythropthalmus, Trochus olivaceus, and Turbo olivaceus.