How do single polyps build into a reef? What conditions do reef-building corals require to grow? Where in the world are coral reefs found? The clear, warm waters of the tropics are home to perhaps the most dramatic environment on earth — the coral reef. Here we find the most breathtakin...
Coral reefs are particularly large colonies of "hard coral" polyps, which secrete exoskeletons made of calcium carbonate, a component of limestone. The polyps grow so close together that their exoskeletons fuse, creating a mass resembling a rocky outcropping....
Each coral species lays down its skeleton in a different way.This gives rise to the extraordinary range of shapes and forms that hard corals take.Some form large boulders, where the polyps live in small, isolated depressions or grooves in the skeleton.Some grow in branches, which can be smal...
These corals are increasingly at risk of bleaching events where polyps expel the zooxanthellae in response to stress such as high water temperature or toxins. Other corals do not rely on zooxanthellae and can live globally in much deeper water, such as the cold-water genus Lophelia which can ...