Chameleons’ Craziest Colour Changes Aren’t for Camouflage

Despite what a widespread myth and fake videos suggest, the creatures have an unexpected motivation to show their most brilliant colours.

Some people are like chameleons: They can blend into any environment with ease. But are chameleons, themselves, like... chameleons?

Yes, and no, scientists say. Contrary to a widely held belief—bolstered by the likes of Disney’s Tangled, which co-stars a chameleon named Pascal—these enigmatic lizards cannot transform the colour of their skin to match any background.

“People believe that if you put a chameleon on chessboard it’s going to hide by taking the same pattern or colour, but this is of course is not true,” says Michel Milinkovitch, an evolutionary geneticist at the University of Geneva and an expert on animal skin colour.

And videos on YouTube, he says, some of which show the lizards changing colours as they encounter different surfaces or objects, “are completely fake.”

Nevertheless, a chameleon’s hue-shifting skills are some of nature’s best—and most multifaceted.

A male and a female Decary's leaf chameleon, Brookesia decaryi. Most chameleons have skin that already resembles their environment, but they can adjust the brightness of the hue in various ways.
PHOTOGRAPH BY CHRISTIAN ZIEGLER, NATIONAL GEOGRAPHIC CREATIVE

Though incapable of matching certain details in their environments, such as bright flowers or individual blades of grass, chameleons can, in fact, make small colour adjustments to blend into their surroundings. And the more dramatic colour transformations—which have made species like the panther chameleon famous—help these lizards defend territory and attract mates.

So while they may not live up to their common portrayal in entertainment media, their use of colour is far more impressive than most people imagine. Let’s take a closer look.

Blending In

Chameleons are often nearly impossible to see—just ask anyone who’s spent time in the field looking for them. “It’s incredibly difficult to spot them,” Milinkovitch says.

And there’s a good reason for it: These lizards are utterly defenceless. They don’t have a dangerous bite, they’re skin isn’t packed with poison, and they can’t move quickly. Staying hidden is pretty much their only tactic to evade predators.

THE ILLEGAL, SECRETIVE WORLD OF CHAMELEON RANCHING

Much of the “blending in” chameleons do doesn’t require colour change at all, Milinkovitch says. In their natural state, they already look a lot like leaves or branches, much like stick insects looks like... sticks.

But these lizards do have the ability to adjust how bright their skin appears, says Devi Stuart-Fox, an evolutionary biologist at the University of Melbourne, who’s been studying chameleon colour for more than a decade.

When there’s less light, she says, such as on a tree deep inside a Malagasy forest, brown to black pigment cells called melanin flood to the skin’s surface and cause the chameleon to appear darker—and thus more camouflaged.

“It’s like putting a dark wash on everything,” Stuart-Fox says. “You’ve got to imagine paint mixing: If you have green paint and mix more black into it, it will change the brightness and also the hue.”

In other words, chameleons can, in fact, change the colour of their skin to match the environment, but within a narrow sliver on the colour wheel. “Chameleons will have a limited repertoire,” she says. “But I have no doubt that within that they can change to match their environment.”

The more elaborate displays, such as when multiple, bright colours appear at once, are saved for another purpose entirely.

A Parson's chameleon, Calumma parsonii, in Madagascar. Chameleons' reserve their most impressive colour-changes for mating and competition.

PHOTOGRAPH BY CHRISTIAN ZIEGLER, NATIONAL GEOGRAPHIC CREATIVE

A Show of Strength

Chameleons have two, opposing states, Milinkovitch says. They either try to be invisible, which subtle colour shifts help them achieve, or try to be seen—again by changing their colour, but this time much more explosively.

No display stands out against the green forest backdrop like that of male dominance. Chameleons are highly territorial: When two males encounter each other, there’s a fierce show-off—in this case, of colour.

“They go nuts,” Milinkovitch says. “They’ll become yellow, red, white—something visible in the tree.”

The weaker male, who’s often smaller and more dimly coloured, will concede defeat by turning off his display first, which indicates that he doesn’t want to fight.

Perhaps he’ll try another tactic instead. Research has shown that some male chameleons will use colour to impersonate females, which allows them to sneak by other males without the threat of competition, much like cuttlefish have been known to do.

Chameleons will also use their displays to dazzle females during courtship. But no matter how brilliant the display, some female lizards won’t be interested—and they’ll use colour to let the men know.

Impressing, Repelling

“The female will react, depending on whether or not she’s available,” Milinkovitch says. If she already has the sperm of another male in her reproductive tracks, he says, “then she’s going to become very dark, and very aggressive.”

Males can be violent, he says, so it’s important that females avoid them if they have no need for insemination. If the female is available she won’t show much colour and instead remains a greenish-brown, Milinkovitch says, indicating submission.

A Malagasy giant chameleon, Furcifer oustaleti, in its native habitat in Kirindi National Park, Madagascar.

PHOTOGRAPH BY CHRISTIAN ZIEGLER, NATIONAL GEOGRAPHIC CREATIVE

Stuart-Fox believes that changing colour may serve yet another, albeit poorly-researched, function: Helping chameleons regulate their body temperature. This trait is widespread among lizards—in a 2016 study, she showed that bearded dragons can alter their skin colour based on temperature—and so it’s unlikely that chameleons wouldn’t also have this ability, she says.

Chameleons are ectotherms, she says, and so they can’t retain heat generated from their metabolism. Instead, they have to warm up using the sun. (That’s why you see lizards basking on rocks in the early morning when it’s cold).

Darker colours absorb more light, and chameleons have likely evolved to capitalize on this principle, she says. When it’s cold and the sun is up, they wash themselves with melanin to darken and thus accelerate warming—unless the colour makes them stand out, that is.

The ability to change colour first likely evolved in chameleons for camouflage, Stuart-Fox says, but the talent now satisfies a wide range of these animals’ needs, like temperature control.

In some cases, the talent satisfies multiple needs at once. In 2003, Stuart-Fox came across Smith's dwarf chameleon basking on a dark-coloured flower stalk while doing field work in South Africa. “It’s perfectly camouflaged,” she says, while also able to “absorb maximum sun.”

“I just think that animals never cease to surprise us in how they can achieve multiple things at once and get the best of all worlds.”

Lead Image: A well-camouflaged juvenile panther chameleon, Furcifer panthera, in its native habitat, in Amber Mountain National Park, Madagascar. The animals are experts at blending into natural backgrounds.

PHOTOGRAPH BY CHRISTIAN ZIEGLER, NATIONAL GEOGRAPHIC CREATIVE

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