Tidepool Tim says,  "I never quite know when i will find a red-gilled nudibranch when i am out in the field collecting.  Sometimes they just appear a by-catch on the deck of the boat or other times i just happen to spot their bright red color as they appear in tiny seawater filled depressions on the rocky beaches. Interestingly this sea slug is able to feed on hydroids and small anemones and tranfer the nematocystys from this food into the cerata (lobes) on its back - thereby allowing itself to deploy these stinging cells into any predator who may want to try and eat it.  This fact and of course the bright red color serve as protective measures. Pretty neat!”