Fluctuating Turban Shell, Turbo fluctuosus

Fluctuating Turban Shell, Turbo fluctuosus. Shell courtesy of the commercial fishermen of the  greater Los Cabos area, Baja California Sur, July 2011. Size: 5.2 cm (2.0 inches) x 5.2 cm (2.0 inches).

Phylogeny: The Fluctuating Turban Shell, Turbo fluctuosus (Wood, 1828), is a gastropod mollusk that is a member of the Turbinidae Family of Turban Shells. The genus Turbo is one of eighteen genera in this family, and there are sixty-one species in this genus.  They are also known as the Gulf Turban, the Eastern Pacific Turban, the Stoney Turban, and the Wavy Turban and in Mexico as Turbante del Pacifico.

Description: Fluctuating Turban Shells are sturdy and consist of five rounded whorls that have angled shoulders. The whorls are sculpted with spiral ridges, which vary from fine to very coarse and nodular. These shells are taller than they are wide. They have a large, round, smooth, aperture. The exterior of the shell is highly variable in color and may be light brown, reddish brown, greenish, or orange, with whitish and dark brown mottling. The interior is iridescent. Fluctuating Turban Shells reach a maximum of 8.6 cm (3.3 inches) of length and 8.6 cm (3.3 inches) in height.

Habitat and Distribution: Fluctuating Turban Shells are found most commonly on, or under, rocks, or over, and within, mud and sand substrates. They live in the intertidal zone, and to depths up to 40 m (130 feet). They are a subtropical to tropical Eastern Pacific species. In Mexican waters they range from Cedros Island, Baja California to Puerto Vallarta, Jalisco,  including the Revillagigedos and Tres Marias Islands. They are found throughout the Gulf of California.

Ecology and Behavior: Fluctuating Turban Shells are herbivorous grazers  that feed primarily on algae, including cyanobacteria and diatoms. They are simultaneous hermaphrodites (each snail possesses both male and female reproductive organs) and reproduce sexually, through broadcast spawning, with external fertilization. There is no mention in the available literature of them engaging in any types of parasitic, commensal, or symbiotic relationships. Fluctuating Turban Shells are popular in the aquarium trade, which could subject them to localized over-collecting. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms: Callopoma (Turbo) fluctuatum, Callopoma fluctuatum, Turbo (Callopoma) fluctuosus, Turbo assimilis, Turbo fluctuates, Turbo fokkesi, and Turbo tessellatus.