Can we solve the riddle of the coral reef halos?

Coral reefs worldwide are threatened by a variety of human impacts. Fishing is among the most pressing threats to reefs, because it occurs on most reef systems and fundamentally alters food webs. Meanwhile, observing coral ...

Soft tissue makes coral tougher in the face of climate change

Climate change and ocean warming threaten coral reefs and disrupt the harmonious relationship between corals and their symbiotic algae, a process known as "coral bleaching." However, a new study conducted by scientists at ...

New eDNA technology used to quickly assess coral reefs

Scientists at the University of Hawai`i at Mānoa Department of Biology have developed a technique for measuring the amount of living coral on a reef by analyzing DNA in small samples of seawater. The new research by Patrick ...

Employing 3-D coral reef remote sensing to predict fish biomass

Coral reefs offer many tropical fish a vibrantly encrusted locale of refuge – a respite from the intense pressures of the sea – providing an opportunity for protection, nutrition and even reproduction. At the mercy of ...

What makes a jellyfish?

Translucent jellyfish, colorful corals and waving sea anemones have very different bodies but all fall on the same big branch in the animal family tree. Jellyfish actually start out anchored to the sea floor, just like corals ...

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Coral

Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea   See Anthozoa for details

Corals are marine organisms from the class Anthozoa and exist as small sea anemone-like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.

A coral "head", commonly perceived to be a single organism, is formed from myriads of individual but genetically identical polyps, each polyp only a few millimeters in diameter. Over thousands of generations, the polyps lay down a skeleton that is characteristic of their species. An individual head of coral grows by asexual reproduction of the individual polyps. Corals also breed sexually by spawning, with corals of the same species releasing gametes simultaneously over a period of one to several nights around a full moon.

Although corals can catch small fish and animals such as plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from photosynthetic unicellular algae called zooxanthellae. Consequently, most corals depend on sunlight and grow in clear and shallow water, typically at depths shallower than 60 m (200 ft). These corals can be major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the enormous Great Barrier Reef off the coast of Queensland, Australia. Other corals do not have associated algae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3000 m. Examples of these can be found living on the Darwin Mounds located north-west of Cape Wrath, Scotland. Corals have also been found off the coast of Washington State and the Aleutian Islands in Alaska.

Corals coordinate behaviour by communicating with each other.

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