What is coral?
While corals may look like rocks and share several characteristics of plants, they are in fact animals. To be exact they are aquatic marine invertebrates (known as polyps) that live in the warm shallows of the clear coastal waters located around the world. A huge number of marine organisms make their home among the corals, making reefs some of the most abundant and varied habitats on Earth. Because the nutrients on which plankton need to feed dissolve better in deeper, cooler water, the warmer layers become a less attractive spot for the huge numbers of floating plankton to occupy. Therefore, the upper shallows remain warm and clear – the ideal living conditions for microscopic algae, which use sunlight to combine carbon dioxide and water to create their own food source, which they share with their coral. Corals live in partnership with single-celled zooxanthellae algae, which are also responsible for the bright colours. If the algae die the coral will turn white, a damaging effect kno...