Fish surprise scientists by glowing red under the waves

Fish have found a colourful way of communicating under the ocean waves - by glowing red.

The find has surprised marine biologists, who presumed the crimson hue had no importance to fish.

They made the assumption because sea-water absorbs ‘red’ wavelengths of sunlight causing objects which look red at the surface to appear grey or black at depths below 10m.

However, researchers have now found at least 32 species can glow red below this depth.

Nico Michiels, from the University of Tübingen, Germany, led the team that captured striking images of the fluorescence at work.

He said: 'Our discovery shows that there is a lot of red fluorescence that is very indicative of an active role of red in fish communication.'

Because the light is coming from the fish themselves and not filtering down from the surface, the red glow remains visible at depth and is easily seen at close distances.

The authors speculated that red fluorescence may function as a 'private communication system' or attraction signal, as proposed for other fluorescent animals.