Coral

See also: Coral (homonymy)

The coral is a microscopic Animal building throughout its life a Carapace which, cumulated with that of its million congeneric, form a coral Récif. However, the coral alone could not live. It functions in Symbiose with a microscopic Végétal : the Zooxanthelle in the Sea S heats and the Plankton in the cold seas.

Places of life

It is an extremely frequent error to believe that the coral can develop only in the hot seas, there forming Récif S and Atoll S. One has known, in fact, for several centuries that the cold seas (broad of the Scandinavia, the Great Britain and the Iberian peninsula) lodge coral Récif S, extremely Poisson neux moreover (certainly reason first of their discovery by the marine of the Northern ).


Various types of corals

One distinguishes from many varieties of coral whose principal ones are: White and pink coral coming from the China Seas and Japan. The red Coral coming from the Mediterranean primarily. The black coral whose consistency resembles the ebony that one finds in the Mediterranean sometimes but especially in the tropical seas.

  • coral hermatypic, alive in Symbiose with the zooxanthelle one needs light and thus lives at a shallow depth.

  • coral ahermatypic, deprived of zooxanthelles. It thus does not need light and can thus live in-depth.

Longevity

The coral colonies are the oldest live animals of the world. Their longevity exceeds by far that of the tortoises living more than 210 years or of the Palourdes quahog which can live more than 405 years. Certain colonies would have several hundreds even several thousands of years according to the experts of the NOAA. (cf http://www.oceanexplorer.noaa.gov/explorations/06davidson/background/ageing/ageing.html)

Symbolic system

Coral in the history and the Mythology: In Greek mythology, the origin of the coral comes from the history of Persée after having triumphed over the Méduse (mythology): indeed the blood of this one would have touched the kelp by petrifying it and transforming it into coral.

The Noces of coral symbolize the 11 years of Mariage in the French folklore.

Threats

Certain corals as the red coral were initially threatened by their exploitation (Bijouterie in this case), then they were victims at the end of the XXe century of the Chalutage in the cold zones and of the continental shelf, to which was added of a deterioration, with planetary scales, said " Bleaching of the corals " , probably multi-factor, causes still badly included/understood being able to result from the conjunction of the Eutrophication, the Pollution, acidity, the Pesticide S, the Manure, the Turbidity of water or the warming, even of a too fast beginning of rise of the oceans, or locally of the presence of pollutants resulting from immersed Ammunition, taking a more or less significant part according to the geographical location. Certain species can survive a few months after having expelled their zooxantelle (3-4 month with Mayotte; 7 months in Florida). A recolonisation of certain corals bleached by Zooxanthelles is sometimes possible, it is a phenomenon observed in several places. Acropores are most sensitive to bleaching (30% died into 91 in the Archipel of the Company/mortality considered as some when a bleached colony outside was secondarily and covered by a felting with filamentous algae; after a few weeks or month.

In Sea of Java, death rate was from 80 to 90% after the episode ENS0 of 1983.

At the end of 2006, at least 40% of the corals of Martinique died of the whitening observed in 2005.

See too

External bonds

  • Summarized concerning the health issues of the corals in the world
  • the corals the depths
  • Presentation of the Corals project of Mascareignes
  • Coral, biology, ecology
  • Vidéos of the Research institute for Development (IRD) - Forum Biodiversity of the Coral Ecosystems, international forum on the biodiversity of the ecosystems coral

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