Two corals growing side by side. The left colony is bleached: it appears white.

Two corals growing side by side. The left colony is bleached: it appears white.

Two corals growing side by side. The left colony is bleached: it appears white.

Two corals (Porites sp.) growing side by side. The left colony is bleached: it appears white. During bleaching the partnership between symbiotic algae that live inside the coral cells and the coral host breaks down giving the coral a white appearance. The colony on the right is still green/brown and has a healthy population of symbionts living in its tissue.

Image: Iliana Baums, Penn State
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