Book 6, Question 79
Why Do Corals Bleach?
When the water stays too warm for too long, corals get stressed. They push out the tiny algae that live inside them. Without the algae, the coral turns pale and its white skeleton shows through.
From the book
Page from A Million Whys Book 6
More fun facts
- When the water gets too warm, corals push out the algae living in their tissues and turn white.
- Without the algae, a coral loses its main source of food and is more likely to get sick.
- Without their algae, coral polyps are mostly clear, so you can see their white skeletons underneath.
- Changes in light or nutrients can also stress corals and make them bleach.
- If the warm water does not last too long, bleached corals can recover.
- Two-thirds of Australia's Great Barrier Reef has been affected by coral bleaching.
Sources: NOAA Ocean Service, NOAA, NOAA, National Geographic
Questions kids ask
Is bleached coral dead?
Not always. If the warm water does not last too long, it can recover.