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Australia’s Great Barrier Reef (or the GBR as it is known to reef aficionados) stretches for more than 2,300 kilometers (over 1,429 miles) and can be seen from outer space. This largest barrier reef...
Welcome to Moorea, a tiny, isolated island in the middle of the vast Pacific...
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Coral reefs are beautiful, vibrant ecosystems that house roughly one quarter of...
Coral reefs are some of the most endangered ecosystems on the planet that are...

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Sponges are animals that eat tiny food particles as they pump water through their bodies. They are very common on Caribbean coral reefs, and come in all shapes, sizes and colors. There is great variability in their size: some...
Many species of pink coralline algae cover a reef surface in the Southern...
Corals are sedentery animals, so how do they reproduce? One way is sexually...

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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...

The Ocean Blog

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...
Giant clams are one of the many wonders of coral reefs. They can grow up to five feet wide, weigh over 400 pounds, and live for 100 years! They power all that bulk by filter feeding microbes and...
The festive Christmas tree worm ( Spirobranchus giganteus ) lives on tropical coral reefs and resembles a fluffy fir tree adorned with ornaments. The multi-functional branch-like appendages are used...
These beautiful mandarinfish ( Synchiropus splendidus ) are covered in bright blue, red, yellow and orange waves. What they lack, however, are traditional fish scales. They live in western Pacific...
This bluefin trevally is lucky to call Hawaii’s Maro Coral Reef, part of the Papahānaumokuākea Marine National Monument , its home. Maro is the largest reef in the Northwest Hawaiian Islands and just...
What are corals? Corals themselves are animals. But tropical reef-building corals have tiny plant-like organisms living in their tissue. The corals couldn’t survive without these microscopic algae–...
Is it lights out for corals once they have experienced a bleaching event? Not necessarily. This photo shows a coral reef near Bocas del Toro, Panama that is in the process of recovering from a mass...
The branches of a primnoid coral in the genus Calyptrophora provide a habitat for galathaoid crabs. Learn more about the deep-sea coral reefs in our Deep-sea Corals article .
This forest of Christmas tree worms is a group of polychaete worms that live on tropical coral reefs. See more celebratory ocean creatures in our slideshow!
Grey reef sharks ( Carcharhinus amblyrhynchos ) are among the most versatile and tough predators on a Pacific coral reef, but they are also among the most vulnerable species, as they are threatened...
I still haven’t gotten beyond the ‘gee whiz’ factor of studying communities of animals in deep-sea coral habitats. Climbing over undersea mountains and along the steep cliffs of submarine canyons...
This bubblegum coral ( Paragorgia arborea ) has a fanlike shape. It is growing 1,310 m (4,298 ft) deep on the Davidson Seamount southwest of Monterey, California. Learn more about deep-sea corals in...
Colorful corals and brittlestars inhabit the Manning Seamount in the Atlantic Ocean, off the coast of New England. Here you can see golden-colored coral (Enallopsamia rostrata), pinkish-brown coral (...
Dr. Martha Nizinski holds a specimen of a fan sponge ( Phakellia sp. ) collected at a deep-sea coral study site off the coast of South Carolina. Deep-sea corals and sponges provide structure for a...
This bearded fireworm ( Hermodice carunculata ) must have a strong stomach -- it’s sucking on fire coral ( Millepora sp. ), which would give the unlucky snorkeler a nasty sting. Encountered in St...
Stare at a tide pool and you will often see a crust of pink coating the bottom. No, this is not bubblegum from some careless teenager’s shoe: it’s a stony kind of seaweed that, like other seaweeds,...
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 .
Imagine you’re an alien seeing Planet Earth for the first time. What do you see from your spacecraft? A blue planet with over 70% of its surface covered by ocean. From space it’s obvious how...
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