These brown-mottled nudibranchs can be found in large numbers where barnacles are abundant. While juveniles feed on bryozoans, adults feed on barnacles by drilling down through the tough outer plates with a specialized, sharp radula (like a rasping tongue) then sucking out the tissue. They have an annual lifecycle and can be found in massive numbers during breeding season. After a major winter spawning event where they lie ribbon-shaped egg masses on shallow rocks, most adults die. This leaves room for larvae of the next generation to settle and grow following a planktonic growth stage.