Coral Reefs

Called the “rain forests of the sea,” coral reefs are important ocean ecosystems that support a quarter of all marine organisms despite covering less than one percent of the sea floor.

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If you look closely, you can read a message in the corals. We are not being metaphorical. Barry and Aimee Brown set out to search for hidden letters among brain coral colonies two years...
The majestic and highly predatory red lionfish ( Pterois volitans ) , native to...
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Reef biologists over a certain age are haunted by memories of what glorious...
by Laura Brodbeck A special type of marine protected area (MPA) called a “no-...

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Compare the healthy coral on the left with the bleached coral on the right. Increased water temperatures caused the bleached coral to lose the microscopic algae that give the coral color and provide it with food. Corals can...
The Oculina deep-sea coral reef at top has not been disturbed by humans—but...
What are corals? Corals themselves are animals. But tropical reef-building...

DIVE DEEPER

It may be the last place you’d expect to find corals—up to 6,000 m (20,000 ft) below the ocean’s surface, where the water is...
In the past 30 years, the Great Barrier Reef -- Australia's iconic natural wonder -- has lost half of its coral to a combination of forces. Dr. Nancy Knowlton, Sant Chair of Marine Science at the...
It may be the last place you’d expect to find corals—up to 6,000 m (20,000 ft) below the ocean’s surface, where the water is icy cold and the light dim or absent. Yet believe it or not, lush coral...
Dr. Stephen Cairns is a research zoologist and chair of the Department of Invertebrate Zoology at the Smithsonian’s National Museum of Natural History. His research focuses on the diversity,...
Convict surgeonfish ( Acanthurus triostegus ) are the roaming sheep of the reef but, instead of noshing on grass, they feed on algae. Their grazing helps to balance the growth of algae and coral on...
One of the first signs of a sick coral reef is seaweed creeping across the corals, stealing their precious sunny real estate. Healthy corals, however, aren't completely hopeless: in some reefs, small...
Species of deep-sea gold coral, or Gerardia , often have a tree-like shape, as you can see in this specimen. See more pictures of coral in our Deep-sea Corals article.
How do we know what coral reefs looked like hundreds of years ago? Often times, we are simply left wondering. Scientists can get an idea from naturalist recordings, but there are many unknowns and...
Tiny plant-like organisms called zooxanthellae live in the tissues of many animals, including some corals , anemones, and jellyfish , sponges, flatworms, mollusks and foraminifera . These microscopic...
Dr. Amy Baco-Taylor observed corals like these on her first submarine dive to a deep-sea coral bed off the coast of Hawaii. They include primnoids, zoanthids, and Gerardia . The high density and...
A master of disguise, the pygmy seahorse ( Hippocampus bargibanti ) grows to only 2cm in length and matches the gorgonian coral that it lives on. The pygmy seahorse is so successful at hiding that it...
Papahānaumokuākea, a chain of islands northwest of the main Hawaiian archipelago, is home to vibrant coral reefs with scores of fish species. It was designated a Marine World Heritage Site in August...
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