Zoologists are discovering that many animals, particularly mammals, fluoresce at night.
This is totally unexpected, but biologists realize that almost all animals fluoresce. Why is that ? Hervé Poirier, editor-in-chief of the scientific magazine Epsiloon, explains to us today that this subject divides zoologists.
franceinfo: The fluorescence of animals. What is this matter?
Hervé Poirier: The subject is futile compared to the biodiversity crisis, or the ongoing wars. But yes, for 5 years now, at nightfall, researchers, in the forest, in zoos or in the corridors of museums, have had fun directing the beam of their ultraviolet torches towards wildlife. , et note, surprised, that many species have a partly fluorescent body, with spots on the skin, fur, plumage or bones.
Does this mean that these animals glow in the night?
Not like glow worms. This concerns the ability to absorb UV radiation to restore part of it in the visible spectrum. A bit like Macumbawhen teeth and nails start to shine on the dance floor. So far, observations have been scattered.
Australian researchers wanted to see things more clearly. They have made the most comprehensive review to date of mammalian fluorescence. They observed under three UV wavelengths, a platypus, five marsupials, a koala, a rabbit, a hairy-nosed wombat, a short-beaked echidna and a cat, all held in the collections of the Western Australian Museum. To confirm that yes, it is real fluorescence.
They then expanded the survey to 125 species, representing 79 families among the 27 orders of living mammals. And only one showed no external fluorescence: the spinner dolphin.
Does it serve a specific function?
The debate is tearing the community apart. According to statistics, fluorescence is more common and intense for nocturnal species (at sunrise and sunset, the light contains more UV), for those with arboreal and burrowing habits, under the bluish light of the undergrowth, and for those with a light and solid color.
Some put forward the hypothesis of a camouflage, a communication signal, or even an argument of seduction. It could also protect against harmful ultraviolet radiation. But others get angry, asserting that these are only accidental properties: it would not occur to anyone to say that the teeth and nails that shine in nightclubs have an adaptive trait.
Knowing that the visual abilities of animals are poorly understood: what do they really see? Even if it is futile, the mystery of animal fluorescence remains. With the new Australian study, it continues to grow.