Hard, soft, white or coloured, solitaire or in colony, the coral is the most atypical creation of nature. Actually, its incredibly diversified aspect and amazing composition make it an animal. Which most people still ignore today!
It is made up of a conglomeration of polyps whose skeleton, which it produces on its own, is made up of limestone. If it was stone for some, and flowers for others, it was only in the course of the 18th century that a young doctor from Marseilles named Peyssonnel declared that "the flower of this so-called plant is in fact an insect comparable to a small nettle". Alas, like all scientific discoveries, this particular one was not widely accepted until Tremblay, a Dutchman, handed over his works to the great scientist, Reaumur, so that the latter may be convinced and thus make a first step towards acknowledging the animal nature of this "flower".The symbolic power of corals.Known since prehistory - painted relics can still be found in certain caves - this "product of Gods" was being used by the Egyptians, Greeks and Romans in the creation of objects and jewellery. According to a Greek legend, Perseus severed the head of a Gorgon, and laid it on a cushion of seaweeds, which was then inundated with blood. And the petrified blood thus created the coral, which gained ground across the oceans before long.The coral has also been the object of various beliefs across history. During the Middle Age, people used to hide a piece of coral in their purse, thought then to be a talisman against witchcraft! They were absolutely certain that it could render the harvest fertile and keep away thunderbolt from the boats. Looked upon as a sacred stone by the Tibetans and the American Indians, the coral symbolized "the energy of the vital force" and protected against the evil eye.One who kept a red coral thus invigorated his blood circulation, while the pink coral was known to have an influence on the heart, the seat of all emotions. Its protection was thus strong against nutritional deficiencies and depression. By helping images to set in our subconscious, the coral encouraged meditation. On the other hand, Arabian tradition made use of the coral against dysentery, as eyewash, and even as toothpaste! For the Christians, it will of course symbolize the blood of Christ.
Many corals.The coral, a branch of the Coelenterates, can be found in many diverse forms. Nevertheless, it is from the red coral: Corallium rubrum that the term coral includes nowadays the different groups of the animal.There exist two classes of corals, those having eight tentacles (octocorallia), and possessing their own internal skeleton like the red coral, the fire coral, the gorgonias or the soft coral. While those with multiple tentacles of six (hexacorallia), better known under the name of Madreporaria, are mostly colony animals equipped with an external calcareous skeleton. Each polyp of the coral secretes a skeleton, hard or soft. It will thus be able to grow each year from a few millimeters to several centimeters.With all their colours borrowed from the rainbow and their most diverse and unbelievable forms, the corals, opened in giant umbrellas, in cushions bristling with needles, in horns of an stag, brains, bushes, branches, laces, labyrinths, flowers, whips... offer us an infinite and extraordinary view, created by a very grand lady indeed, Mother Nature!
Life and death of the coral.The polyp (hermaphrodite) of the coral is the result of the meeting of a spermatozoid and an ovum, originating from its own sexual glands. In the clear waters of warm seas in particular, it is at night that suddenly the "heads" of corals, ressembling tiny sea anemones, open up and in a genuine scintillating explosion, give birth to millions of male and female gametes, which, while amalgamating, will give birth to larva called Panula. The latter will then disperse to the surface of the waters to finally fall back on the coral reefs and in turn will be transformed into polyps. The embryonic polyps will thus settle, divide, live and die on the reefs while waiting for the following year and a new call from the moon…To build their skeleton, the polyps will extract calcium carbonate from the seawater and transform it into limestone sealed by microscopic sponges and seaweeds. When these will die, the skeleton will still remain. As such, the coralline colonies are the results of hundreds of dead polyps covered with living ones, which will die soon when their turn comes.But what do polyps eat? Well, simply plankton. Remember that the plankton is a group of microscopic beings, animal or vegetal (algae, larva of crustaceans, eggs of fishes…), that can be found scattered in the waters. Moreover, most of the corals live in perfect symbiosis with the "zooxanthellae", microscopic algae that, by the process of photosynthesis, transform solar energy into food and thus provide the corals with the necessary products for the calcification of its skeleton. In turn, the algae feed themselves on the organic by-products of the metabolism of the coral. However, a stressing situation is enough (yes! the coral can be "stressed"!) for the tiny algae to be rejected and our coral, aged prematurely, will turn white and can even die of this cause!Corals are at times solitary, but more often form and live in colonies. As such, coral reefs are created from the accumulation of these madrepores. Some are 5'000 years old. In general, they develop themselves in the shallow zones of warm seas. Actually needing oxygen and sunlight to accomplish successfully their process of photosynthesis, they stay where the sunrays can still penetrate the waters. The Great Barrier Reef of Australia, the atolls of Maldives or Polynesia, and the coral reefs of the Red Sea illustrate perfectly these conditions.These genuine coralline "forests" live in perfect harmony with numerous plants and animals. They provide shelter to myriads of multi-coloured fishes. The Damselfish use them as a hiding place, the parrotfish savour them, and the echinoderms (sea urchins, starfish) feeding on algae, clean the reef. Tiny translucent shrimp imitate their colour, similarly to the chameleons, and conceal themselves, whilst, small spider-crabs tie living polyps to their shells so as to blend perfectly with their host as well. The octopus makes good use of the coral reef to hide its eggs, and the grouper often halts for a rest among the reefs... In brief, the coral is an ideal shelter against predators! Alas, the coral has plenty of foes…
The enemies of the coral.If the butterfly fishes eat the polyps with relish, and the parrotfish graze the corals and spit out the limestone in the form of small vaporous clouds, the Acanthaster ("Crown-of-thorns") which can measure up to 60cm in diameter, is the most dreaded! This starfish evaginates its stomach, spread it out like a leech that covers up the remotest relief to lick, suck in, dissolve the coral and victorious, digest it...Here I will also mention the cyclones that damage the reefs, and the too big fluctuations in the rise or fall of temperature, because the coral is more fragile than it appears, it eventually dies above 29° and below 18°. Desalination, harmful UV, diseases are the main causes. Without forgetting its principal predator: Man! Well before Jesus Christ, the coral had already been seducing the jewellers... the red coral decorated the jewels, helmets and fibulas. During the 15th and 16th centuries the use of the coral was widespread across the globe, but it is in China and Japan, then in Italy that coral art would be the most flourishing. On the other hand, the Arabs worked the black coral to chisel out necklaces. As for the coral fishermen, they sold their catch to tourists in search of a souvenir of the islands!
Little by little, the bottom of the oceans is being deprived of its coralline ornament, the shelterless fishes migrate to other territories, some species even disappear forever. On the atolls of Maldives, coral is used to build embankments and houses: the coral reefs explode with the massive use of mines!The pollution, which wreaks havoc when domestic wastewater is discharged in the lagoons, deteriorates dangerously the coral reefs. Fortunately, some measures are being taken to safeguard them. Often, coral fishing is prohibited. Every place where coral is present, more and more efforts are being carried out to "educate" the population by inculcating them with respect for the environment and thus coral, in the form of information, dissuasions, and even prohibitions. Tourists are also invited to care for the environment and not to yield in to temptations.Polyps, architects and talented decorators, establish surprising structures, which offer food and shelter to its tenants and cohabit in perfect harmony with the latter. But the coral reef remains a fragile and threatened ecosystem. With its fauna and flora, it is in itself a microcosm of our small blue planet. Thus, there remains for us to take great care of it...
Text: © Valérie Claro • Photos: © Fabrice Bettex / Mysterra
Scientific Name: Millepora alcicornis
