These watercolor sketches of Trapezia crabs were drawn by Frederick Bayer, a former Smithsonian coral biologist, in 1947. Trapezia crabs live on and within corals, feeding on their tissue and mucus, and protect them from predators such as crown-of-thorns starfish. Bayer made these drawings in 1947, during a survey of marine fauna on the coral reefs of Bikini Atoll in the Pacific, one year after the US military tested nuclear bombs there. Read more about how the bombed reef has recovered.