Close-up of a Coral Polyp

Close-up photograph of translucent coral polyps, showing the symbiotic algae living inside.
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In this close-up photo, you can actually see the photosynthetic algae, or zooxanthellae, living inside a tiny coral polyp. Look for the brownish-green specks in the colorless polyp. Corals depend on these algae for food and for some of their oxygen. To learn more about coral reefs, explore our featured ecosystem Coral Reefs.

Tags: Algae Corals