Onchidoris bilamellata

The Rough-Mantled Doris

Phylum Mollusca
Class Gastropoda
Subclass Opisthobranchia
Order Nudibranchia
Family Onchidorididae
Genus Onchidoris
Species bilamellata

Description: 2.5 cm long, 2 cm wide; dark brown, cream or orange; broad, oval, plump body covered with many short, knobby projections; 16 to 32 bushy gills arranged in two semi-circular half rings near posterior of animal; two comblike rhinophores.

Habitat: Found near muddy bays, on rocks, pilings, and docks from well above high tide lines to water 10 m in depth.

Natural History: It feeds on sponges, barnacles and bryozoans, especially M. membranacea. Sponges are an important part of their diet because they contain a chemical which the nudibranchs use for defense. It is common intertidally during winter and spring. This nudibranch has an annual life cycle. They have one spawning season from December to May. During this season the adult nudibranch spawns repeatedly.