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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Coral reefs are beautiful, vibrant ecosystems that house roughly one quarter of all marine species and provide billions of dollars in products and services to humans each year. But they are also vulnerable to...
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The pre-industrial American landscape was once rightly described as a place...
If you look closely, you can read a message in the corals. We are not being...
The majestic and highly predatory red lionfish ( Pterois volitans ) , native to...

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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...

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Coral reefs are the most diverse of all marine ecosystems. They teem with life, with perhaps one quarter of all ocean...
Overfishing and sedimentation have heavily impacted this reef off the western coast of Guam. More about coral reef ecosystems can be found in our Coral Reefs featured story .
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...
Corals, sponges, and algae are the major components of most coral reef communities. To the untrained eye, they are sometimes difficult to tell apart. More about coral reef ecosystems can be found in...
When snorkeling in the Kahekili Herbivore Fisheries Management Area (KHFMA) in West Maui, I keep an eye out for certain kinds of fish. Not the brightest or the biggest, but those herbivores such as...
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...
Flower-like clusters of polyps make up this coral colony. Their pink color comes from the zooxanthellae living inside. More about coral reef ecosystems can be found in our Coral Reefs featured story .
By Lindsay Aylesworth, Project Seahorse The day I stepped into my wetsuit, donned my mask, and embarked on my first scuba dive was the day I decided to be a marine biologist. Little did I know that...
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...
If you don’t like purple, you can look for this anemone (Condylactis sp.) in green. It comes in different colors and brightens a variety of Caribbean reef habitats, from lagoons to deeper waters.
While bottom trawling—a fishing method that drags a large net with heavy weights across the seafloor—fishermen often catch more than their target fish. Here, they've scooped up a large deep-sea coral...
Sit down with two veteran marine scientists, Dr. Nancy Knowlton and Dr. Jeremy Jackson, who fell in love with each other and the reefs of the Caribbean 40 years ago. Those reefs are now gone due to...
The Johnson-Sea-Link submersible reaches the ocean’s surface with a specimen of Keratoisis bamboo coral inside its collection box. Find out how ocean scientists study deep-sea corals in our Deep-sea...
In this photo of a shallow coral reef in the Pacific there are three species of forams . On the left, Peneroplis planatus . In the center, Amphistegina lessonii . And on the right, Laevipeneroplis sp...
Dead man’s fingers ( Alcyonium digitatum ) are soft corals named for their appendage-like appearance when thrown ashore by storms. The finger-like clumps of coral polyps come in various shades of...
An aerial photo of Carrie Bow Cay and the Smithsonian research station looking north with Twin Cays in the background. The Smithsonian’s Carrie Bow Cay Marine Field Station supports research projects...
Two events made me passionate about deep-sea corals . One was my first submarine dive in a deep-sea coral bed off the Hawaiian island of Oahu. There was an incredibly lush community of corals and...
A crown-of-thorns starfish ( Acanthaster planci ) on a reef in the Marianas Islands. An “outbreak” of these coral-eating starfish can decimate a reef, and they have done great damage on Australia's...
Scientists have been studying why populations of crown-of-thorns sea stars ( Acanthaster planci ) have mushroomed in recent decades. Coral reefs can suffer when the sea star's numbers explode because...
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