A Fijian reef explodes in color as a school of anthias swims past. If a soft coral hosts zooxanthellae (the algae that give coral the nutrients it needs to grow) and the water becomes too warm, the algae leave and the soft coral die. Unlike hard corals, soft corals don’t leave a limestone skeleton behind and cannot regenerate.
Photograph by Tim Laman

Appearing as flowers of the sea, the tentacles of an orange cup coral reach out in the waters of the Caroline Islands in Micronesia. Known for their brilliant colors, these corals inhabit the shallow areas of coral reefs.
Photograph by Heather Perry

A diver explores an emerald kingdom in New Zealand’s Wet Jacket Arm marine reserve. Black coral creates an undersea forest for colorful reef fish and can live for 300 years. Aiding its marine ecosystems by creating reserves, New Zealand hopes to protect 10 percent of its waters by 2010.
Photograph by Brian J. Skerry

Shelves of coral surround the Pacific island of Palau. Corals, small organisms related to anemones, secrete calcium carbonate, which hardens into an exoskeleton and over time forms reefs.
Photograph by Tim Laman