This coral orientates itself so that its cup surface is parallel to the surface to which it is fastened and it sways with the water movement. During the day, the mantle tissues absorb water and swell up. This increases the area exposed to the light and may double the coral's diameter. The zooxanthellae are photosynthetic and use sunlight to create organic compounds. These provide most of the coral's energy needs. However, during the night, the tentacles of the polyp are extended to trap planktonic particles floating past and these supplement the nutrition it obtains from photosynthesis.
