Ornate Nerite Shell, Nerita scabricosta

Ornate Nerite Shell, Nerita scabricosta. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 1.2 cm (0.5 inches) x 1.0 cm (0.4 inches) x 0.8 cm (0.3 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Ornate Nerite Shell, Nerita scabricosta. Shell collected off the beach of Bahía Concepción, Baja California Sur, October 2019. Size: 2.1 cm (0.8 inches) x 1.6 cm (0.6 inches).

Ornate Nerite Shell, Nerita scabricosta. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 2.8 cm (1.1 inches) x 2.1 cm (0.8 inches) x 1.6 cm (0.6 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Phylogeny: The Ornate Nerite, Nerita scabricosta (Lamarck, 1822), is a gastropod mollusk is a member of the Neritidae Family of Nerite Shells.  The genus Nerita is one of thirteen genera in this family, and there are seventy-four species in this genus. They are also known as the Costate Nirite Shell and the Rough-ribbed Nerite Shell.

Description: Ornate Nerite shells are solid and consist of four rounded whorls, with a low apex. The  exterior is sculpted with numerous, rough, rounded, ribs that run along the whorls. The aperture is large and has a toothed outer lip and a wide toothed inner lip. The exterior of the shell is dark gray, with varying amounts of white specs or blotches. The interior is white, with varying amounts of yellow to tan blotching. The outer lip of the aperture has a black band. Ornate Nerites reach a maximum of 5.1 cm (2.0 inches) of length and 3.9 cm (1.5 inches) in length.

Habitat and Distribution: Ornate Nerites are found on rocks in the higher intertidal zone. They migrate up and down with the tide and are known to follow in one another’s trail. They do so by following visual cues, unlike most snails, which follow chemical cues.  They are a subtropical to tropical Eastern Pacific species. In Mexican waters they range from San Juanico, Baja California Sur south to Guatemala, including the Revillagigedo Islands. They are found throughout the Sea of Cortez.

Ecology and Behavior: Ornate Nerites are herbivorous grazers that  feed on algae.  They are gonochoric and reproduce sexually, through broadcast spawning. 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 consider to be of Least Concern.

Synonyms: Nerita (Nerita) scabricosta, Nerita deshayesii, Nerita fuscata, Nerita multijugis, Nerita ornata, Nerita papilonacea, and Nerita scabricostata.