It’s well known that chameleons change color for camouflage, but new research in the journal Biology Letters finds that the colors directly reflect the chameleon’s mood, status and more. This veiled chameleon looks to be a healthy, handsome stud, given his overall body condition and many bright colors.
“The neat thing about chameleon color change is that it is under both hormonal and nervous system control, as well as being sensitive to light and temperature,” lead author Russell Ligon, of Arizona State University’s School of Life Sciences, told Discovery News.
Many animals display fairly static coloration, such as feathers in different hues that pretty much stay the same shade. There is never a dull moment with chameleon colors, though.
Ligon explained, “I think that it's likely chameleons have evolved rapid, dramatic color change because they need an efficient way to communicate with one another while living up in trees, on small branches, etc. and elaborate behavioral displays might be harder to perform or riskier up on the top of a tree!”
Ligon and colleague Kevin McGraw determined that during competitions, veiled chameleon males with brighter stripe coloration were more likely to escalate encounters, while those displaying brighter, rapidly changing head colors were more likely to win these fights. Here, an aggressive and brightly colored male chases his darker and retreating opponent out of the trial arena. Both chameleons are shedding, but most of the colorful signals are still visible.
“The bright chameleon on the left has approached his opponent from the bottom of the trial arena," Ligon said, "and his competitor on the right is beginning to pull himself up in preparation for a retreat!”
“After trading head-butting blows, the chameleon on the right knocked his opponent (on the left) from his perch,” Ligon said. “Fortunately for the left individual, he was able to maintain a grip on the perch with his specialized, zygodactyl toes and prehensile tail.”
"Zygodactyl" refers to having two toes pointing forward and two that point backward.
The chameleon on the right became darker as his counterpart, aggressively displaying and brightly colored, approached him from across the arena.
Such dramatic color changes can be tied to hormones and metabolism. “Chameleons do not necessarily have more extreme hormonal or energetic fluctuations -- (it's) just that normal fluctuations in these parameters become outwardly manifest in the colors and speed of color change they exhibit,” Ligon said.
“Rearing back, an open-mouthed male veiled chameleon prepares to lunge at his opponent, Ligon said, "in an attempt to displace him from his perch.”
Color changes happen during chameleon battles, but they also occur during romantic encounters as well.
“In veiled chameleons, I only have one observation of male courtship, but the female displayed a beautiful light green with subtle blues and yellows while the male was courting,” Ligon said. “After copulation, she rapidly changed to a dark, black color punctuated with spots of yellow and blue. Her behavior changed immediately after copulation as well, going from passive participant to aggressively hissing and displaying to keep the male away from her.”