These previously unknown tardigrades, assigned to the Paramacrobiotus genus, exhibit natural fluorescence, casting an eerie blue glow when exposed to ultraviolet light.
What’s more, and as the authors of the new study argue, this fluorescence protects the tardigrades from levels of UV radiation known to kill other microorganisms, such as bacteria and viruses.
Fifteen-minute doses delivered at 1 kilojoule per square meter wiped out most individuals from a tardigrade species known as Hypsibius exemplaris, and all were dead after 24 hours.
“After UV radiation treatment, tardigrades were observed daily for signs of life—active movement and egg laying,†wrote the authors in the study.
The exact mechanism of protection remains unknown, but Eswarappa’s team suspects the fluorescent shield absorbs harmful UV radiation and emits harmless blue light.