Corals cover less than 1 per cent of the ocean floor but they support over one-third of the world’s marine life. The Zoological Society of London has drawn up a list of the , as part of its EDGE (Evolutionarily Distinct and Globally Endangered) of Existence project. The list highlights 10 species vital to our understanding of coral evolution that could help predict the how reefs will respond to climate change.
Ghost of the past
Despite being one of the fastest-growing coral species, with colonies able to grow by 4 to 11 centimetres per year, elkhorn coral () no longer dominates Caribbean reefs. Like many corals, it is threatened by coral bleaching, which occurs when symbiotic algae that live on the coral die – because of rising water temperatures, among other factors. The algae provide food and pigment to their hosts, so when they die, the coral takes on a ghostly white appearance.
Between May and October last year, Indonesian reefs in the famous Coral Triangle lost up to 80 per cent of Acropora reef colonies because of mass bleaching events.
Threat: bleaching, storms, white band disease
(Image: Erik Brun)
Elegant killer
Don’t let its soft, fleshy appearance fool you. Elegance coral () uses its tentacles to prey on shrimp or other small meaty treats.
Threat: bleaching
(Image: Tim Wijgerde)
Sex under a full moon
To maximise their chances of being fertilised, colonies of elliptical star coral () spawn en masse, releasing thousands of eggs and sperm into the water at the same time. These spawning events often coincide with a full moon.
The species suffers from a disease called white plague. As a result, colonies living in the Florida Keys have suffered a 75 per cent decline since 1995.
Threat: white plague, bleaching
(Image: ZSL)
Skyscrapers of the seas
grows in columns that reach up to 2 metres. They are covered in tentacles, giving them a hairy appearance.
Threat: white plague, storms, bleaching
(Image: Andre Seale/SplashdownDirect/Rex Features)
Solitary mushroom
Unlike many other corals, the (Heliofungia actiniformis) does not form colonies. Instead, the mushroom-like blobs have large, lobed teeth and mouth parts that can be up to 3 centimetres long. Mushroom coral provide a home to many other species, including the colourful popcorn shrimp () and a species of pipefish ().
Threat: aquarium trade, bleaching
(Image: Wolfgang Krutz/Waterworxs)
Stomach outreach
has an aggressive side. It is able to extend its stomach onto the living tissue of an adjacent coral and destroy it. It is a species of brain coral.
Threat: bleaching, fisheries
(Image: Charles Sheppard)
