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

Construction equipment alongside a stream near a road Construction underway to restore fish passage on the Little Tonsina River. Credit: Copper River Watershed Project.
A coral reef with bleached corals appearing white Corals in Kāneʻohe Bay demonstrated a range of bleaching responses during the 2019 heat stress event. Credit: Chuck Babbit Photography
White corals releasing a shimmering cloud into the water as they spawn. Credit: Johnston Applied Marine Science. Coral spawning in the Commonwealth of the Northern Mariana Islands, captured during work initiated under the Ruth Gates Restoration Innovation Grants in 2020. Credit: Johnston Applied Marine Science.
Photo of rockfish next to and under deep sea sponge on Alaska seafloor. Rockfish associated with deep sea sponge in Alaska. Credit: NOAA Fisheries.


Peer-Reviewed Research

Coral Taxonomy and Local Stressors Drive Bleaching Prevalence Across the Hawaiian Archipelago in 2019

The Hawai‘i Coral Bleaching Collaborative conducts 2,177 coral bleaching surveys across the…

Peer-Reviewed Research

Spatial Distribution and Sources of Nutrients at Two Coastal Developments in South Kohala, Hawai’i

A study documenting how nutrients are distributed within coral reef developments for better…

NOAA Live! Alaska

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

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…


Understanding Ocean Acidification

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

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