Updated by: Arabinda Naik
Coral Reefs are a kind of calcareous rock, chiefly made of the skeletons of minute sea organisms called 'polyps'. Coral reefs and atolls are formed due to the accumulation and compaction of the skeletons of these lime secreting organisms. Only the upper and outer part of coral reefs is housed by living coral polyps. The skeleton of calcium carbonate of coral polyps is deposited one upon another after their death. These carbonate skeletons are cemented and compacted to form reefs. Vaughan (1917) has defined coral reef as “a ridge or mound of limestone, the upper surface of which is near the surface of the sea and which is formed of calcium carbonate by the actions of organisms, chiefly corals.”
The coral reefs are, in fact, produced by corals belonging to Anthozoa, particularly by stony corals, the Madreporaria. Hence, these are supposed to be the principal builders of coral reefs though there are certain other contributors also. A coral reef, in fact, is a ridge of limestone whose upper surface is just below the sea surface, and it is exposed at low tides. Coral reefs are among the world’s most diversified ecosystems and are home to a broad diversity of marine creatures, including fish, crabs, and molluscs. Coral reefs provide crucial habitats for many of these species, as well as important ecological services, such as preventing erosion and storm damage to shorelines.