If you thought chameleons changed colour in order to blend in with their background – you’d be wrong. It’s actually all about body language. Changing colour is how these charismatic little lizards talk to each other.
If I asked you to imagine a colour changing animal, the chances are you’ll think of Chameleons, right? Me too. Which is interesting, because colour change is frequent across many taxa in the Animal Kingdom.
So why would an animal change it’s body colour anyway?
Well, some animals (like the snowshoe hare) use colour change to evade predators undetected. Some (like the marmalade hoverfly), use it for physical benefits like thermoregulation. Others may use it as a warning signal (like the blue-ringed octopus). Whereas others could use it for social signalling, such as with the subject of this article; the South African dwarf chameleon.
Popular culture has let us believe that chameleons are the masters of disguise. Even as i’m writing this i’m imagining that scene from Disney’s Tangled where Pascal camouflages into a plant pot. And for many years, scientists too believed that camouflage was the driving force behind the evolution of their colour changing ability. Until fairly recently.
A study by Stuart-Fox and Moussalli, (2008) shows that the colour changing in 21 lineages of South African dwarf chameleons (Bradypodion spp.) is more likely to be an adaptation to communicate. Not to camouflage. It turns out that the chameleons use their vibrant colourations when partaking in male-male competition (competing for mates) and in courtship.
It’s always important to remember that the purpose of an animal’s colouration depends on how it appears to it’s intended observer, not how it appears to us. This is because other animals don’t necessarily see the same colours as we do. Luckily, the study accounted for this. The study used visual models of how both chameleons and their avian predators perceive chameleon colour variation. Still, they found no evidence that these chameleons are using their colour change in order to camouflage ( called the crypsis hypothesis ).
The author writes “… capacity for colour change is unrelated to variation in the environmental backgrounds that chameleons must match in order to be camouflaged. Overall, our results suggest that the evolution of the ability to exhibit striking changes in colour evolved as a strategy to facilitate social signalling and not, as popularly believed, camouflage.”
South African dwarf chameleons belong to the genus Bradypodion . These are native to southern Africa, hence their collective name.
Sciencey stuff aside, there’s no denying that South African dwarf chameleons (especially the Cape Dwarf Chameleon pictured in this article) are quite possibly the coolest looking lizards on Earth. Just look at all those colours! Also, they’re teeny tiny, about 15cm long .
I think I’ve found my new favourite animal.
Reference:
Stuart-Fox, D. and Moussalli, A., 2008. Selection for social signalling drives the evolution of chameleon colour change. PLoS biology, 6(1), p.e25.
