David Prötzel, Zoologische Staatssammlung München
A group of German scientists recently discovered a species of gecko has a surprising, hidden talent.
Under UV light, the web-footed gecko glows a bright fluorescent green around its eyes and down its sides.
The scientists found guanine crystals sitting inside pigment cells called iridophores on the areas of the gecko that fluoresce.
Iridophores are already well studied, and neither they nor guanine crystals are thought to directly cause fluorescence.
It’s also a mystery what advantage these neon patterns might hold for the gecko.
In that case, thin, raised scales provided a “window” to view the fluorescent bones beneath.
In most cases, scientists are unconvinced that fluorescence helps animals, though it could play a role in camouflage, mating, or communication.
Jonathan Martin, Northland College
Those are the leading theories as to why platypuses glow under UV light, as researchers from Northland College in Wisconsin found last year.
The same researchers found certain flying squirrel species glowed pink in UV light, too.
Dr. Kenny Travouillon, Western Australia Museum
Following these discoveries, members of the Western Australia Museum took a blacklight to the museum's collection, finding a bright glow in some unexpected creatures, including wombats.
Lajos Endredi / 500px/500Px Unreleased Plus/Getty Images
One recently discovered fluorescent compound in scorpions could protect them from parasites.
The more scientists look into it, the more common bioluminescence appears to be among the animal kingdom.
Oxford Scientific/Photodisc/Getty Images
The truly baffling questions are why animals evolved to glow this way in the first place — and, in many cases, how they manage to glow so brightly.
Read more stories about animals here