A UCLouvain team has shown that the kitefin shark, a deep-sea species, uses the light emitted from its belly to hide its silhouette from prey beneath it. The study was published in the scientific journal iScience.
Researcher Jérôme Mallefet measured the intensity, colour and direction of the light produced by the photophores, the light-emitting organs in the sharks’ skin. The light was found to spread much further sideways than in other bioluminescent animals, and the shark also uses it to detect prey in the dark.
Until now, counter-illumination was seen mainly as a defence used by vulnerable animals. According to Mallefet, the study shows that the strategy can also help a predator make a stealthy approach. Five years earlier, the same team had shown that the species is bioluminescent, making it the largest known luminous vertebrate.
