Coral at the Great Barrier Reef

This colorful coral lives in Australia's Great Barrier Reef. On the whole, this coral reef is the largest single structure built by living organisms and can be seen from space! Although more than one-third of the reef is protected from fishing and other human impacts, it is still 50% smaller than it was just 30 years ago. Learn why it is disappearing from Nancy Knowlton, the Smithsonian's Sant Chair of Marine Science.