Cup Coral

Photo: Australian Aquatic Survey Ecology · CC BY-NC-ND

Orange cup corals are azooxanthellate corals that thrive in the shaded interiors of caves and overhangs where light levels are too low for photosynthetic symbiont-bearing corals to survive. They feed entirely by capturing zooplankton with extended tentacles at night, creating spectacular orange-and-yellow displays on cave walls when illuminated by dive lights. Their filter-feeding lifestyle makes them important food-chain links between pelagic zooplankton production and the benthic communities of cave ecosystems.