Some chameleons have glowing skulls

Chameleons already have the colour changing, the independent eyes and the tongue. It turns out they were hiding one more trick, and nobody noticed until 2018.

Blue dots in the dark

When researchers at the Bavarian State Collection of Zoology in Munich shone a UV lamp on chameleons from their collection, small blue dots lit up across the heads of many species. In some, the glow ran along the crest and down the face. In a few, it spread across the body.

It's the bone that glows

The glow comes from small bony bumps on the skull called tubercles. Bone naturally fluoresces under UV light. On these bumps, the skin is so thin that it acts like a little window, letting the UV in and the blue glow out. The team published their findings in Scientific Reports and called it bone-based fluorescence.

Why would a chameleon glow?

Nobody knows for certain yet. One clue is that in most species of the Madagascan genus Calumma, males have noticeably more of these glowing bumps than females. That points to some kind of signal, possibly for recognising their own species or for attracting a mate. The researchers also noted that many of the glowing species live in shaded forests, where a blue glow would stand out against the green.

Can you see it at home?

Many keepers have tried with a UV torch. If you do, keep it brief and never shine the light into your chameleon's eyes. And don't be disappointed if yours doesn't light up. The glow varies a lot between species, and the study didn't cover every chameleon in the hobby.

Either way, it's a great answer next time someone asks what's so special about chameleons.

Thinking about a chameleon? Shop the ZM Chameleon Kit