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 that is a member of the Littorinidae Family of Periwinkle Shells. 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.  They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent from north of Guerrero Negro, Baja California, along the central and northwest coasts of the Baja Peninsula.

Ecology and Behavior: Aspera Periwinkles are grazers that feed primarily on algae. They are eaten by shorebirds and crabs. They are gonochoric and reproduce sexually, through broadcast spawning. The eggs are laid in protective capsules. They’re engagement in any type of commensal, parasitic, or symbiotic relationships has not been formally documented. From a conservation perspective Aspera Periwinkle has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Littorina aspera and Nodilittorina aspera.