Dazzling, colourful, breathtaking. These are just some of the words used to describe coral reefs.
The "rainforests of the sea" are the world's most biologically diverse marine ecosystem. Home to a quarter of all ocean dwelling fish, coral reefs also feed, protect and inspire hundreds of millions of people around the world. More importantly, the health of coral reefs is a sensitive barometer for the health of our oceans and our planet.
Coral reefs are structures made up of a complex association of marine organisms, mainly the coral animals themselves, cemented by the growth of coralline algae. Coral reefs have existed for 450 million years, probably making them the oldest ecosystems on the planet.
Contrary to popular belief, corals are living animals that grow, feed and reproduce. They get most of their food from zooxanthellae, a unicellular algae that lives symbiotically within their tissues. Coral reefs are therefore normally found in clear, shallow water as the algae requires sunlight to photosynthesize.
Corals can be divided into hard and soft corals. The former produce a calcium carbonate skeleton and are the key contributor to coral reef formation