Coral Skeleton

Part of Hall of Planet Earth.

Lobate Coral

Coral reefs are built by large colonies of small invertebrate animals that grow skeletons from chemicals in seawater. The composition of the skeletons changes in response to fluctuations in the ocean, such as water temperature. As a result, reefs record local climate over the corals' lifetimes, including El Niño events.

Coral and Climate Change

Pollution and human-caused climate change are already impacting coral reefs. Warmer oceans stress the colorful algae that live in reefs, bleaching the coral. Prolonged bleaching can kill reefs altogether. Increasing ocean acidification will further threaten coral as the sea absorbs CO2 from the atmosphere.