Intertidal Invertebrates of the Monterey Bay Area, California

Compiled & photographed by Gary McDonald, Long Marine Laboratory, University of California, Santa Cruz

Description: Dorsum brownish to almost black, with small yellow flecks and numberous large papillae. Rhinophores long with about 20-28 lamellae. Branchial plumes 7, bipinnate, brown, usually tipped with yellow, arranged in a circle around anus. May emit pungent odor of cedar when handled. Most likely feeds on bryozoans. Very rare in the intertidal. Similar to the more common Onchidoris bilamellata, which has shorter rhinophores; lower, rounded tuberlces on dorsum, and branchial plumes arranged in 2 arches around the anus.