White Hoof Shell, Anatisabia foliacea

White Hoof Shell, Anatisabia foliacea. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 2.1 cm (0.8 inches) x 1.7 cm (0.7 inches) x 1.1 cm (0.4 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Phylogeny: The White Hoof Shell, Antisabia foliacea, Quoy & Gaimard 1835, is a gastropod mollusk that is a member of the Hipponicidae Family of Hoof Shells. The genus Antisabia is one of eight genera in this family, and there are four species in this genus. This species is also known as the White Hat Shell.

Description: The White Hoof Shell is cup-shaped and lacks the spiral coil of most gastropods. The shell is thick and has an irregular oval outline. The apex is somewhat posterior and pointed rearward. The apex is blunt and often eroded in adult specimens. The exterior of the shell is sculpted with irregular concentric lamellae and fine radial lines, forming imbricate scales on specimens that avoid erosion. These shells are white in color. The interior is smooth, with a horseshoe shaped muscle scar. They have a brown periostracum. White Hoof Shells reach a maximum of 2.2 cm (.8 inches) in length.

Habitat and Distribution: White Hoof Shells are found on, and under, rocks, intertidally, and to a depth of 15 m (49 feet). They are a subtropical to tropical species, found throughout the Indian and Pacific Oceans. Their range in Mexican waters is very poorly documented. Some sources omit this species from the entire Eastern Pacific, while others claim they are found along the entire west coast of Mexico, including the entire Gulf of California.

Ecology and Behavior:  White Hoof Shells are grazers and suspension feeders, which feed primarily on organic fragments, detritus, and pieces of algae. Because they are sedentary, they use their extendable snout to reach food sources and are dependent on water movement to bring them food. They are sequential hermaphrodites, beginning life as males and transitioning into females. They reproduce sexually, through broadcast spawning. The eggs sacs are brooded under the female’s shell. Beyond their sometimes being an epibiont on other shells, 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 very wide distribution and should be consider to be of Least Concern.

Synonyms: Hipponix foliacea