December 12, 2013
Chameleons Colors Convey Information During Combat
[ Watch the Video: Communicating Chameleons Rely On Color ]
redOrbit Staff & Wire Reports - Your Universe OnlineWhile the color-changing abilities of chameleons are typically thought of as a defense mechanism, new research published online Wednesday in the journal Biology Letters suggests that the lizards could actually use the trait to communicate with other chameleons as well.
Doctoral candidate Russell Ligon and associate professor Kevin McGraw of the Arizona State University School of Life Sciences studied one type of chameleon and learned that the lizards change color when attempting to convey different types of information with other chameleons during key social interactions.
“For example, when male chameleons challenge each other for territory or a female, their coloring becomes brighter and much more intense. Males that display brighter stripes when they are aggressive are more likely to approach their opponent, and those that achieve brighter head colors are more likely to win fights,” the university said in a statement, adding that the speed with which their heads change hues can predict which one would win in a fight.
Ligon and McGraw used photographic and mathematical modeling tools in order to study how veiled chameleons used their color change abilities in response to aggressive behaviors. They looked at the distance, maximum brightness and color change speed of 28 different patches at various regions throughout the creatures’ bodies.
While the resting colors of chameleons typically range from brown to green (with some hints of yellow), each individual lizard has unique markings, the researchers said. When one of the chameleons is challenged, it will show bright yellows, oranges, greens and turquoises.
Furthermore, when they 'showed-off' their stripes at a distance and quickly followed that up with a head-on approach prior to a skirmish, the vital color signals on the striped parts of the head and body became accentuated. Ligon said that, based on their observations, the winner of a fight is “often decided before they actually make physical contact” and is typically “the one that causes its opponent to retreat.”
According to Ed Yong of National Geographic, the ASU investigators set-up duels between two male members of the nearly two-foot long, aggressive lizard species. Typically, the two males would stare each other down for a few seconds before one realized he was overmatched and backed down – though on the occasion when neither backed down and they did square off, the researchers were forced to intervene.
“As the lizards squared off, the duo photographed them every four seconds, and measured the brightness and colors of 28 body parts. They also converted their photos according to the technical specifications of chameleon eyes, to see the individuals as other chameleons would see them,” Yong said. “They found that the brightness of the chameleons’ stripes predicted how likely they were to approach their rivals.”
In fact, that alone was found to account for over 70 percent of the variation in the chameleon’s motivation, the National Geographic writer said. When it came to the brightness of the lizards’ heads, this trail was found to account for 83 percent of the variation of their fighting ability, he added.