Intertidal Invertebrates of the Monterey Bay Area, California

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

Description: Ground color, including cerata, oral hood, and rhinophores is translucent yellowish-brown, occasionally with a slight blue-green tinge. Body irregularly dotted with numerous small, bluish-white dots. Liver branches usually light green to brown. Oral hood elliptical and arched dorsally, margin with numerous cirri. Cerata readily dehiscent; laterally flattened, broadly ovate to round in outline, the slightly truncate tips bear 2-6 small acute points. Rhinophores with 5-6 lamellae, shaft with a thin, triangular sail-like expansion on inner face.
Size: Typically about 50-100mm in length, but individuals up to 300mm have been reported.
Notes: Usually found on kelp, occasionally on kelp which has drifted in to docks in bays. The large oral hood is used to capture small crustaceans, especially copepods which dwell on the blades of Macrocystis. This species can swim by flexing the body laterally, back and forth.