Coral reef formations are the jewels of the ocean. Their beauty and diversity make coral reefs an irresistible attraction for every marine life lover. Although they occupy only 0.1% of the world’s ocean surface, these very diversified ecosystems host more than a quarter of all marine species.
Reefs prefer the tropical climate; they love the sun, so they grow mainly in shallow, clear, agitated, warm waters. There are, however, deep and cold water corals too, although not so many.
The coral reef building process can be explored from two points of view: the formation of individual reefs and the formation of full ecosystems. Don’t forget to check thesea.org’s coral reef section.
Individual coral reefs begin to form when a coral larva attaches itself to underwater rocks or other hard surfaces and begins reproducing asexually, by budding. The reefs grow and expand slowly through accumulation and sedimentation of limestone and by incorporating a large number of marine plants and animals.
If we want to take a closer look at the process of coral reef formation, we need to explain what a coral is. The coral animals are called polyps. They are very small and are shaped like a cylinder. From the two ends, one is the mouth, surrounded by minuscule tentacles, and the other is used to attach to the skeletons of dead polyps, or to rocks, if it is a free-swimming larva. A flat sheet of tissue connects the polyps to each other by the middle of their bodies, thus forming a coral colony.
With the calcium taken from the seawater, the coral polyps build the limestone skeleton, which is basically the foundation of the colony and, then, the reef. Even if a polyp dies, as long as the colony is still living, new polyps will grow on the skeleton of the dead one, and will cover it with a thin layer of tissue. This new growth is the first step in the forming of a reef.
While a colony is formed of only one species of coral, reefs structures can consist of several species of coral, hard and soft, algae, and sponges.
When talking about reef ecosystems formation, we need to broaden our horizon and see further than plants and animals. The large scale reef structure is influenced by abiotic factors, as well, such as: see depth, light penetration, substrate composition, water movement.
A complex and beautiful structure like the coral reef takes between 5,000 and 10,000 years to establish.