October 28, 2021
A coral reef is a reef-shaped structure in the sea, formed by anemones and which over time becomes large enough to have a significant ecological and physical impact on its environment. These are the largest structures built from living organisms in the world. The total area of coral reefs is 600,000 km², and in the Maldives the reefs rise to 2,200 m above the seabed. Coral reefs are mostly built of coral from the Scleractinia group, but fire corals (Millepora) as well as blue corals (Heliopora coerulea) in the tropical Indo-Pacific also participate in the construction of the reef. Scleractinia can survive from great depths to the shallows, all the way to the surface of the sea. For many centuries, they built the structure of the ridge from their skeletons composed of calcium carbonate. Coral reefs are complex marine ecosystems. They are a biotope (area of life) of a biocenosis (community of living beings) consisting of plants and animals, for example worms, shells, sponges, echinoderms and crustaceans. Coral reefs play a significant role as "breeding grounds" for the offspring of fish that inhabit the high seas. A coral island is formed through long-term changes in water levels. Since the coral reef can only grow to the sea surface, one or more islands, usually in the form of atolls, are formed by lowering the water level or raising the bottom. Most corals that build coral reefs live in a mutualistic relationship with a special type of photosynthetic alga Zooxanthelle. Algae received substances for photosynthesis from coral, as well as a place to live, and at the same time supplying it with the necessary compounds for life, glucose, amino acids, glycerol. Corals, with their metabolic activity, complicate these simple compounds, thus obtaining material for performing all life functions. The role of Zooxanthella is to ensure the continuous circulation of matter. The color of coral comes, in fact, from algae, making corals a unique ecosystem. Corals are very productive ecosystems and are important, not only for the species they live in, but also for humans. The following facts indicate that corals are of great ecological importance: Fishing - For almost a quarter of all the world's fish, coral reefs are a habitat. The presence of coral determines how well-bred the fish will be, which are later caught and form the basic means for numerous human communities in the world.