Shell of the Week: The Elusive Souverbie Lobiger

The Souverbie Lobiger, Lobiger souverbii P. Fischer, 1857, is a sea slug that reaches about 15 mm (0.6 inch) in length. Its cap-like, translucent shell (below) is very thin, covers only the central-dorsal part of the animal, and is flanked by the four parapodial lobes typical of the genus Lobiger. Most likely, the lobes act to increase the apparent size of the animal. That, combined with production of a sticky substance, probably acts to intimidate potential predators.

Lobiger souverbii from Lake Worth Lagoon, Palm Beach County, Florida. Photo by Anne DuPont.

Living Souverbie Lobigers may be very difficult to observe, as they display cryptic coloration, i.e., the green color of the animal mirrors the color of its habitat and preferred food, green algae in the genus Caulerpa.

Lobiger souverbii, three views of the shell from Cayo Costa, Florida. Photos by José H. Leal.

The shell illustrated in this piece was collected in January 2019 by Ann Palmer, at Cayo Costa. The photo of the live sea slug (was taken by Anne DuPont at Lake Worth Lagoon, Palm Beach County. Read more about mollusks and their shells in the Museum's Shell Guide and Blog.