Corals are diverse groups of invertebrate animals. Coral polyps are tiny, soft-bodied organisms that are related to jellyfish and sea anemones.

Different species of coral are found in different habitats and different locations around the world. Hard corals like lobed star coral and pillar coral are reef-building corals. Colonial hard corals, consisting of hundreds to hundreds of thousands of individual polyps, are cemented together by the calcium carbonate “skeletons” they secrete. As colonies grow over hundreds and thousands of years, they join with other colonies and become reefs. Some of the coral reefs on the planet today began growing over 50 million years ago.

Soft corals do not produce a rigid calcium carbonate skeleton and do not form reefs, although they are often found in reef ecosystems. Soft corals are also colonial animals. Often, what appears to be a single large organismresembling trees, bushes, fans, and whipsis actually a colony of individual polyps combined to form a larger structure. 

Coral reefs teem with life. Although they cover less than one percent of the ocean floor, they support about 25 percent of all marine creatures. Corals are particularly vulnerable to the effects of human activities including pollution, climate change, sedimentation, and fishing. Under the Endangered Species Act, more than 25 coral species are listed as threatened or endangered. 

NOAA Fisheries works to better understand and conserve coral species and coral reef habitats both domestically and internationally.

Species News

Diver monitoring corals A diver monitoring restored corals. (Photo: Reef Renewal Bonaire)
2250x1687-2018.09.28-Coral-Reef-Scar-StevenGnam.jpg The marine debris team removing a large derelict fishing net from the reef at Pearl and Hermes Atoll. The impact area of the net can be seen as a pale patch on the coral reef in the upper right corner of the image. Photo: NOAA Fisheries/Steven Gnam.
A diver attaching corals to the reef bottom A diver attaches corals to the reef bottom. (Photo: Reef Resilience Network)

Research

Feature Story

The Impacts of Ghost Nets on Coral Reefs

Ghost nets are silently drifting through the Northwestern Hawaiian Islands, snagging on coral reefs and entangling wildlife. Scientists in the Pacific Islands have observed ghost nets tumbling across expansive coral reef environments. They break, shade,…

NOAA Live! Alaska

NOAA Live! Alaska is a series of webinars that connects NOAA scientists and partners with students, teachers, and Alaska communities.

Peer-Reviewed Research

Successful Application of a Novel Technique to Quantify Negative Impacts of Derelict Fishing Nets on Northwestern Hawaiian Island Reefs

Use of structure from motion to quantify impacts of derelict fishing nets on shallow water coral…

Habitat and Groundfish Ecology Research in the California Current

A program of the Southwest Fisheries Science Center’s Fisheries Ecology Division. The Habitat and Groundfish Ecology Team studies deep-water California demersal communities and habitat assemblages, the goal being to provide sound scientific…

Insight

Understanding Ocean Acidification

Learn how our oceans are absorbing increasingly more carbon dioxide from the atmosphere, leading to lower pH and greater acidity.

sombrero-reef-elkhorn-coral-NOAA and Jessica Levy_750x500.jpg

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