Why do animals put their energy into making light? One reason to emit light is that, in the ocean, the sunlight barely penetrates deeper than a few hundred meters. Below that, it is completely dark. During the night, even the ocean surface is dark, except for the faint glow from the moonlight, so light is a great way for animals to communicate. But who are they communicating with and who else is seeing these signals? For marine species, emitting light or looking for light in the darkness helps them to find partners or even something to eat. For example, the angler fish uses its glowing lure to attract small prey that will undoubtedly end up in its stomach. Of course, since the prey do not want to be eaten, they can use bioluminescence too, but as a defense. Many different strategies can be used. Shooting a cloud of luminescent mucus is a way to leave predators dazzled for a few seconds. Indeed, imagine that you have been in a dark room for a few minutes.

License information: CC BY 4.0
MPAA: G
Go to source: https://kids.frontiersin.org/article/10.3389/frym.2020.00069