Coral Reef

A coral reef looks like a colorful underwater garden, but it is alive. It is made up of millions of tiny animals called coral polyps. Between the corals, countless colorful fish make their home.

For scientists

Coral polyps live in symbiosis with tiny algae (zooxanthellae) that dwell in their tissue and supply most of their food through photosynthesis; this is why reefs need clear, sunlit water. The reef builds up over thousands of years from the limestone the polyps lay down. If the water gets too warm, the corals expel their algae and bleach white, and then often starve.

Source: NOAA

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