Tardigrades are these invertebrate animals that have amazing faculties, including that of having adapted to live in the most hostile environments. Among the hundreds of species, there is one, Hypsibius exemplaris, which has just revealed another of its fascinating capacities, that of resisting lethal doses of UV radiation.
Titanic in size from 0.5 to 1mm in length, tardigrades are endowed with many superpowers. For example, among the 1,300 species discovered, some resist the vacuum of space. To nothing. To the strict absence of everything – and also to solitude, therefore. In comparison, the tardigrades of the genus Paramacrobiotus perhaps considered themselves a bit commonplace. They then developed their own natural fluorescence. Not very original. There are also species of corals and auto-fluorescent frogs . Not at all discouraged, these tardigrades have honed their skills. Until their fluorescence gives them tolerance to deadly UV rays , reports a study published in Biology Letters .
Using a natural variant devoid of fluorescence, the researchers explain, they found that the fluorescence of the tardigrade Hypsibius exemplaris protected it from UV rays. Emitted by the sun , most species have strategies to protect themselves from it. In this case, the fluorescent screen of the tardigrade would absorb said UV radiation and in return emit harmless blue light .
A first experimental proof
Scientists already suspected that photoprotection could be one of the functions of fluorescence in certain organisms. But no experimental proof had yet been provided. Through their research, the three Indian scientists behind this study provide the first evidence that ” photoprotection is attributed to fluorescence under UV light “.
They suggest that the ability of Hypsibius exemplaris to resist lethal doses of UV radiation stems from their adaptation to the Indian climate . The other species present in the same moss habitat as this tardigrade may have evolved into other protective mechanisms. By living, for example, deep enough inside the moss so that UV radiation cannot reach them, suggest the authors