Science

The secret to the chameleon’s glow

Chameleon 2

Chameleon 2  

On January 15, an article was published in Scientific reports showing that chameleons can glow under UV light. It reported that at around 430 nm of UV light, a blue colour was seen in the bony part protruding from the skull and the colour could be seen through their scales. This was in contrast with the green and brown background of their forest habitats. The authors write that this “wavelength..might appear brighter to chameleons as their visual spectrum is in shorter wavelengths (from about 350 nm to 650 nm) compared to the human visual perception(400nm to 700nm)”

One of the authors of the paper, Mark D. Scherz from the Department of Herpetology at Zoologische Staatssammlung München (ZSM-SNSB) institution, Germany, explains more about chameleons in an e-mail interview to The Hindu.

Can you tell me more about how these chameleons might be using this fluorescence?

We are not really sure. Probably they are used to augment the existing colour patterns, and maybe to provide some stable patterns around the changeable ones in their skin. It may help females choose a good male mate, based on how much fluorescence he is showing, because it's possible the fluorescence is an indicator of the condition of the male - lots of fluorescence means a nice healthy male. This kind of 'honest indicator' is common in animals, and is often used in mate choice.

A large number of marine creatures are known to fluoresce, any reports in terrestrial creatures? I heard that scorpions also have fluorescence properties.

A surprising number of animals fluoresce. The photographer Paul Bertner, whose work partially inspired our research, has an excellent gallery of fluorescent photography here: https://rainforests.smugmug.com/Photo-style/Ultraviolet-UV/.

It turns out that a huge variety of arthropods fluoresce, as well as quite a few other terrestrial organisms like birds, a few reptiles, and notably discovered in 2017, some frogs.

The way in which this fluorescence is achieved varies wildly. Scorpions in particular have been known to fluoresce for a very long time, but why they fluoresce is an unanswered question, just like in chameleons.

Apart from change in colour and now fluorescence, are there any other weird chameleon behaviour?

Lots! Chameleons are fascinating animals to study. Big topics of ongoing research on chameleons focus on their ballistic tongues, their evolution and relationships, new species (several described every year), their eyesight, and miniaturisation (the smallest amniote in the world is a chameleon arguably, though there is a gecko that might compete).

Small chameleons often have a hard time finding each other, and in some species the male rides around on the female's back until she is ready to mate. The different mating rituals of chameleons are surprisingly varied actually, but this has not been well studied. They tend to be really quite different from other lizards.

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Printable version | Jul 9, 2020 8:38:38 AM | https://www.thehindu.com/sci-tech/science/the-secret-to-the-chameleons-glow/article22480006.ece

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