Pointed Slipper Limpet Shell, Crepidula excavata

Pointed Slipper Limpet Shell, Crepidula excavata. Shell collected off the beach in Cabo San Lucas, Baja Calfornia Sur, July 2018. Size: 2.5 cm (1.0 inch) x 1.6 cm (0.6 inches).

Phylogeny: The Pointed Slipper Limpet Shell, Crepidula excavata (Broderip, 1834), is a gastropod mollusk that is a member of the Calyptraeidae Family of Cup-and-Saucer and Slipper Limpet Shells. The genus Crepidula is one of eleven genera in this family, and there are forty-nine species in this genus. They are also known as the Excavated Slipper Shell, and in Mexico as Caliptreido Babucha and Pique Del Pacifico.

Description: The Pointed Slipper Limpet Shell has an irregular oval or parrot-beak outline. The shape of the shell is somewhat determined by the shape of the surface they are attached to.  The apex extends to the margin of the shell. The exterior is sculpted with fine commarginal ridges. The internal “shelf” is set well below the shell’s margin and covers about half the aperture. The exterior color can vary, being white with tinges of brown, pink and/or yellow. Some individuals have brown lines or spots. The interior may be white, tan, or dark brown. The interior shelf is white. Pointed Slipper Limpet Shells reach a maximum of 3.5 cm (1.4 inches) in length and 2.2 cm (0.9 inches) in height.

Habitat and Distribution: Pointed Slipper Limpet Shells are found in the intertidal zone, and to depths up to 8 m (25 feet). They are often found attached to larger snail shells, especially moon snails. 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 the west coast of the Baja Peninsula.

Ecology and Behavior:  Pointed 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. 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 considered to be of Least Concern.

Synonyms: Calyptrea excavata.