Pictured in the newest AquaNerd Picture of the Week is a Lettuce Nudibranch (Elysia crispata). While most nudibranchs are not desirable in the home aquarium, this little sea slug serves one very beneficial function…consuming unsightly algae. The lettuce nudibranch, which technically isn’t a true nudibranch, consumes different types of algae from the rockwork and incorporates the photosynthetic chloroplasts from the algae into its own cells. This allows the nudibranch to derive some of its nutrition from light energy, making it very easy to keep these slugs fed in the aquarium. Because of their diet, they are completely reef safe, but do occasionally find their way into the propellers of water pumps.