THE natural food of gorgonians, or any other soft corals, inhabiting coral reefs is unknown, but net photosynthesis to respiration ratios from 2 to 5 have been reported for isolated colonies of five species of Caribbean reef gorgonians in laboratory experiments1,2. This photosynthesis is attributed to the dinoflagellate symbionts living in the gastrodermal cells of these and other so-called hermatypic corals. There is also evidence that members of the gorgonian family Xeniidae in the Red Sea draw most of their nutrition from this photosynthesis3. Observations reported here suggest that gorgonians from Caribbean reefs may also depend for nutrition on their algal symbionts.