Aspera Periwinkle Shell, Echinolittorina aspera

Aspera Periwinkle Shell, Echinolittorina aspera. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, December 2018. Size: 1.0 cm (0.4 inches) x 0.7 cm (0.3 inches).

Phylogeny: The Aspera Periwinkle, Echinolittorina aspera (R. A. Phillipi, 1846), is a gastropod mollusk in the Littorinidae Family of Periwinkles. The genus Echinolittorina is one of seventeen genera in this family, and there are sixty-two species in this genus. The name “Aspera” comes from the Latin word for rough or uneven that can refer to the surface texture, shell outline, or color variations.

Description: The Aspera Periwinkle shell has five to six whorls with the anterior whorl being large, giving the shell a squatty appearance. The shell has a sharply pointed apex. These shells are highly variable in external sculpting and coloration; some have a series of fine ridges following along each whorl while others have fine radiating lines. The exterior of the shell is light brown to white in color, with brown or grayish markings that appear as radiating straight or wavy lines, zig zags, revolving lines that look like a series of dashes, or diagonal lines. Some specimens have bluish spots; most individuals have at least some chocolate brown around the aperture. The Aspera Periwinkle Shells reach a maximum of 2.0 cm (0.8 inches) in height and 1.4 cm (0.6 inches) in width.

Habitat and Distribution: Aspera Periwinkles are found attached to shoreline rocks, in the mid to high intertidal zone. They are often in clusters of many dozens of individuals. Aspera Periwinkles are a subtropical to tropical Eastern Pacific species. In Mexican waters they range from Guerrero Negro, Baja California to Guatemala. They are also found throughout the Gulf of California.

Ecology and Behavior: Aspera Periwinkles are grazers that feed primarily on algae. They are eaten by shore birds and crabs. They are gonochoric and reproduce sexually, through broadcast spawning. The eggs are laid in protective capsules. 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: Littorina aspera and Nodilittorina aspera.