The Hopkin's Rose nudibranch (Okenia rosacea) might be described as the Rastafarian nudibranch of California. While nudibranchs aren't actually known to practice any religion, the bright pink papillae covering the dorsal surface of this species has a certain resemblance to the dreadlocks worn by adherents of the Rastafarian faith. These papillae aren't the gills, or branchial plumes, of the animal, rather just extensions that cover the back. The gills and rhinophores are often completely hidden by the papillae, however you can see the rhinophores on the left side of the photo, two or three papillae from the left and a couple of papillae up from the bottom. The rhinophores are rose pink and have a blunt tip compared to the papillae.
These nudibranchs preferentially dine on the rose-colored bryozoan, Integripelta bilabiata, and the color match is likely no accident, since both the bryozoan and the nudibranch both contain hopkinsiaxanthin (hopkins-ee-ah-zanthin), a rose-red pigment.
Hopkin's Rose nudibranch is just one of many brilliantly-colored nudibranchs found along the Pacific coast of North America.
This photo was taken with a Canon EF100 mm f/4 lens on a Canon EOS 10D in an Ikelite underwater housing. Lighting was provided by two Ikelite DS-125 Substrobes in eTTL mode. The exposure was set to 1/60 sec at f/19 and ISO 100.
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