Article body copy Though reminiscent of a discarded clump of salad greens, this is actually a lettuce sea slug. I spotted it 20 meters below the surface on a coral reef off Playa Kalki, an idyllic beach on the northwestern edge of Curaçao. Bright video lights and a macrophotography camera in an underwater housing let me capture this invertebrate in all its colorful glory. Named for the undulating waves of its broad, fleshy appendages—called parapodia—lettuce sea slugs appear in a range of...