We Just Discovered Chameleons Have Fluorescent Bones That Glow in the Dark
While most maintain that the late Jim Morrison of The Doors earned his psychedelic honorific, "The Lizard King," a new reptile might pose a significant challenge to Morrison's crown.
Researchers at the Bavarian State Collection of Zoology in Munich have discovered that chameleons, which are known to change their color in order to disguise themselves among the surface they rest on, are also blacklight reactive. The bony protrusions on the heads of several species become fluorescent when exposed to ultraviolet light, forming gorgeous patterns that even your uncle's Grateful Dead tapestry can't match.
"It has long been known that bones fluoresce under UV light, but that animals use this phenomenon to fluoresce themselves has surprised us and was previously unknown," says Dr. Frank Glaw, Curator of Herpetology at the Bavarian State Collection of Zoology.
The patterns that form seem to vary among certain species groups. Most male species in the genius Calumma, for instance, have more fluorescent bones exposed than the females. This has led the researchers to suspect that the fluorescence is not a coincidence, but rather another defense mechanism, intended to help the animals recognize members of the same species.
"[T]he known fluorescent properties of bone has never before been shown, yet it is widespread in the chameleons of Madagascar and some African chameleon genera, particularly in those genera living in forested, humid habitats known to have a higher relative component of ambient UV light," reads the study's abstract. "The fluorescence emits with a maximum at around 430 nm in blue color which contrasts well to the green and brown background reflectance of forest habitats. This discovery opens new avenues in the study of signaling among chameleons and sexual selection factors driving ornamentation."
Using advanced Micro-CT scans, the team also compared the distribution of the fluorescent patterns to chameleons' skeletal structure, determining that the flourescant spots lined up perfectly with the animal's bony bumps and ridges.
"Our histological 3D reconstruction shows that the skin covering the tubercles on the skull is very thin and consists only of a transparent layer of epidermis," Dr. Martin Heß from the BioCenter of the Ludwig-Maximilians-Universität München explained. These patches effectively act as windows that enable UV light to reach the bone, where it is absorbed and then emitted again as blue fluorescent light.
Biogenic fluorescence is common among marine organisms, but incredibly rare in land-dwelling vertebrates. "[W]e could hardly believe our eyes when we illuminated the chameleons in our collection with a UV lamp, and almost all species showed blue, previously invisible patterns on the head, some even over the whole body," lead study author David Prötzel, said of the discovery. The team agrees that there are likely more UV-reactive mammals just waiting to be discovered.
In related glowing news, MIT invented glowing plants last month by introducing chemically interacting nanoparticles into the leaves of a watercress plant. h
In relates lizard news, a creature resembling an ancient Loch Ness Monster was recently uncovered in Antarctica.