Bleached coral and giant clam - 4K stock video

Bleached coral on a reef, contrasting with a healthy region of coral and a giant clam (Tridacna sp.). Bleaching occurs when corals expel their symbiotic algae, which normally inhabits their body tissues and is responsible for their colour. The algae photosynthesises and provides food for the coral, so its loss severely weakens to coral colony. Bleaching occurs in response to environmental stresses, including raised water temperatures. Healthy coloured corals are seen in the middle of the clip, with a giant clam seen at the end. Filmed on the Great Barrier Reef, Australia.