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

Coral recruits in a flow-through tank. Coral recruits from 2021 spawning (mountainous star coral, Orbicella faveolata; staghorn coral, Acropora cervicornis; elkhorn coral, Acropora palmata) Credit: NOAA Fisheries/ Allan Bright (Permit: FKNMS-2018-163-A1).
A fish found in Puerto Rico, the roughtongue bass, swimming along structure-forming corals on the seafloor. In 2014, researchers exploring the waters around Puerto Rico found fish such as this roughtongue bass among structure-forming corals on the seafloor. Scientists are studying the ways in which fish interact with corals to better understand deep-sea ecosystems. Credit: NOAA Ocean Exploration
Outplanting staghorn coral Outplanting, or planting coral fragments grown in nurseries back onto reefs, is a type of restoration activity.
An image of a green sponge on the sea floor. The green sponge Latrunculia austini was discovered in 2005 by NOAA Fisheries coral biologist Bob Stone. Hollings Scholar Kaya Mondry spent her summer conducting a literature review on biomedical compounds produced by this species. Credit: NOAA Fisheries


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…

Genetics and Evolution in the Pacific Northwest

Our science supports the conservation and management of marine and anadromous species, from deep-sea corals, to salmon, to whales. We employ advanced genetics and genomics tools to provide essential information for managing sustainable fisheries and…


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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