Coral reef formation is a unique natural phenomenon. It is a diverse ecosystem formed under tropical water. The bio-diversity in a coral reef, have given them the name rain forest of the sea. The coral reefs are home to almost one-fourth of the total species living in the sea. Reefs are mostly found near to coast line in the tropics, but deep-sea coral reefs are also found. The most famous is The Great Barrier Reef of Australia.
The formation of a Coral reef
– Fringing reefs – The first stage of the formation of a coral reef is the coral larvae attaching themselves to rocks or soil near the coasts. The coasts may be of an island or a continent. The larvae become polyps and excrete calcium carbonate, which forms their exoskeleton. The polyps live only in those waters which have enough sunlight seeping though. They have a symbiotic relation with the microscopic algae Zooxanthellae, which helps them grow. As the y grow they secrete more calcium carbonate. The secreted calcium carbonate sediments on the rocks and provides a substrate for more polyps coming to attach themselves to the formation. As more and more polyps attach to the substrate, a coral reef is formed. Calcareous Algae also add their sediments to the structure. The marine animals and plants also add their own remains to the reef as they die and sink. It strengthens the reef and now it can withstand furious storms. The reefs that are initially formed near the coast are known as fringing reefs. Over a period the calcium carbonate converts into lime stone due to pressure.
– Barrier Reef – The fringing reefs slowly combine with each other and form a border line along the coast. The calcium carbonate structures attract more polyps and the spaces are filled up. It forms a line along the coast and a ring around an island. They form beautiful and colorful formations under water. The sunlight coming through helps them grow together. The Great Barrier Reef found on Australian coast is the biggest continuous reef structure in the world.
– Atoll – As the coral grows further, it becomes heavy and pushes the sea rocks underneath and come up significantly. More animals are found in an atoll than the earlier stages. Over a million species can live in one square kilometer coral reef.