Sea slugs are among the most beautiful creatures in the sea. Known also as nudibranchs, they are found in an almost endless assortment of shapes, sizes, and colors. Their bright color patterns are serve as a warning to predators that they taste bad. Some nudibranchs are even poisonous. They are carnivores, feeding on sponges, tunicates, barnacles, and even other nudibranchs. The feathery tentacles on this nudibranch's back are actually its gills, which it uses to extract oxygen from the sea water.