Ridged Slipper Limpet Shell, Crepidula striolata

Ridged Slipper Limpet Shell, Crepidula striolata. Shell collected off the beach in Cabo San Lucas, Baja California Sur, August 2020. Size: 4.3 cm (1.7 inches) x 2.8 cm (1.2 inches).

Phylogeny: The Ridged Slipper Limpet Shell, Crepidula striolata (Menke, 1851), is a gastropod mollusk that is a member of the Calyptraeidae Family of Cup-and-Saucer and Slipper Limpets. The genus Crepidula is one of eleven genera in this family, and there are forty-eight species in this genus.

Description:  Ridged Slipper Limpet Shells have an irregular ovate outline and a low profile. The apex overhangs the shell’s margin.  A large shelf covers about one-half the shell’s interior. The exterior usually has a smooth texture however some specimens are sculpted with low radial ribs. The exterior is white in color with brown around the apex, and sometimes on the ribs. The interior is shiny white, often with brown around the margin. These shells have a shaggy yellow-brown periostracum.  Ridged Slipper Limpet Shells reach a maximum of 5.0 cm (2.0 inches) in length and 3.3 cm (1.3 inches) in height.

Habitat and Distribution: Ridged Slipper Limpet Shells are found on, and under, stones, and on larger gastropod shells. They are found in protected waters from the lower intertidal zone to a depth of 30 m (98 feet). They are a subtropical to tropical Eastern Pacific species. In Mexican waters they are found throughout the Gulf of California and extend as far south as to Guatemala. They have not been documented from the west coast of the Baja Peninsula.

Ecology and Behavior:  Ridged Slipper Limpet Shells are suspension feeders that feed primarily on planktonic algae, which they filter from the water by use of their gills. They are protandrous hermaphrodites, beginning life as males and later becoming females. They reproduce sexually,  with internal fertilization. Ridged Slipper Limpet Shells are associated with the pea crab Calyptraeotheres camposi.  It is thought that this relationship is commensal in nature but more research is needed. From a conservation perspective Ridged Slipper Limpet Shells have not been formally evaluated however they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Calyptraea squama, Crepidula squama, and Crepidula strigatella.