Coral’s neon sunscreen could save reefs

Coral bleaching, where entire reefs can go ghostly white, is becoming an increasing common environmental issue. However, some species have an appropriately colourful way of saving themselves – creating a neon-coloured ‘sunscreen’.

Corals are very unusual animals. Each individual ‘polyp’ is usually only a couple of centimetres across, but they build on top of each to form reefs that can be seen from space. A type of algae lives inside these polyps, providing the coral’s brilliant colouring.

Unfortunately, when the coral gets stressed (caused by, for example, water temperatures becoming too hot), it evicts the algae from its body. When this happens, all that’s left is a pale white ‘skeleton’, and the coral often dies before the algae can return.

Luckily, they have a defence. Under the right conditions, coral can produce their own colouring in various neon shades. As well as making the reef look prettier, this protects algae from the bright light found inside pure-white polyps, speeding up the coral’s recovery.