Healthy coral
Tiny plants called zooxanthellae feed animal polyps through photosythesis on the coral. Interactions between the two generate corals' brilliant colours
'Bleached' coral
If high water temperatures persist for a week or more the polyps reject their plant partners and the coral appears 'bleached'. If the heat persists for too long the coral will die
Dead coral
Algae grows on dead coral making it impossible for new colonies to form. If there are enough fish on the reef they can clean the algae away and allow corals to return
Healthy coral
Tiny plants called zooxanthellae feed animal polyps through photosythesis on the coral. Interactions between the two generate corals' brilliant colours
'Bleached' coral
If high water temperatures persist for a week or more the polyps reject their plant partners and the coral appears 'bleached'. If the heat persists for too long the coral will die
Dead coral
Algae grows on dead coral making it impossible for new colonies to form. If there are enough fish on the reef they can clean the algae away and allow corals to return