During the Day Corals?

Corals exposed during daylight hours are subjected to the most ultraviolet radiation, which can overheat and dry out the coral's tissues. Corals may become so physiologically stressed that they begin to expel their symbiotic zooxanthellae

What happens to hard corals during the day?

The calcification process requires many hydrogen atoms, which during the day can be removed by photosynthesis; at night, however, hydrogen accumulates which increases the acidity of the coral, and therefore STPCA creates extra bicarbonate as a buffer to prevent acid damage.

Are coral polyps active during the day?

Coral polyps are usually nocturnal, meaning that they stay inside their skeletons during the day. At night, polyps extend their tentacles to feed. Most coral polyps have clear bodies.