Dall’s Limpet Shell, Lottia dalliana

Dall’s Limpet Shell, Lottia dalliana. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 4.1 cm (1.6 inches) x 3.7 cm (1.5 inches) x 0.8 cm (0.3 inches).

Phylogeny: The Dall’s Limpet Shell, Lottia dalliana (Pilsbry, 1891), is a gastropod mollusk that is a member of the Lottiidae Family of True Limpet Shells. The genus Lottia is one of fifteen genera in this family, and there are sixty-five species in this genus. They are known in Mexico as Lapa de Dall.

Description: Dall’s Limpet Shells have an ovate outline that narrows toward the anterior. They are  low in profile, with a sharply pointed apex. The posterior slope is smoothly convex.  The exterior is sculpted with fine radial riblets. The exterior is brown with white maculations. The interior is bluish white with a brown center. Dall’s Limpet Shells reach a maximum length of 4.6 cm (1.8 inches).

Habitat and Distribution: Dall’s Limpet Shells are found attached to rocks in the intertidal zone. They are a subtropical Eastern Pacific species, which is endemic to Mexico. In Mexican waters they are found throughout the Gulf of California and range south to Mismaloya, Jalisco, including the Tres Marias Islands.

Ecology and Behavior: Dall’s Limpet Shells are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in Family Lottiidae are 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: Acmaea dalliana and Collisella dalliana