Great Barrier Reef
Length: 1,553 miles (2,500 km)
Location: Coral Sea near Australia
A coral reef is a submerged structure made up of many different corals, or small marine invertebrates. These corals are unable to move and cluster with other corals to form colonies. These colonies then secrete calcium carbonate that causes them to bind together to form the reef. Each of these individual animals is also covered with a hard exoskeleton which makes coral reefs appear very strong and rock-like.Underwater life surrounding these reefs is quite rich. In fact they are usually called the “rainforests of the sea”, because they occupy less than 0.1% of the world’s ocean surface, but still provide a home for 25% of all marine species.Coral reefs vary in size, type and location around the world but they are very sensitive to water properties like temperature and chemical composition.
Great barrier reef is not only the biggest coral reef in the world, but it is also the world’s biggest structure made by living organisms, and it can even be seen from the outer space.