This post was written by ScIU undergraduate student, Sara Hipsher.
Hopefully, we’ve all seen Disney’s Tangled, featuring the cute little chameleon Pascal. Throughout the film, Pascal takes on a range of colors depending on his background as well as his emotions. We see him blending in with teal walls and purple flowers, but we also see him turning red with anger. We’ve grown up thinking chameleons are able to blend into any background, but you may be wondering, is this true? Do chameleons really change their color to match any background or emotion?
How are chameleons able to change their color? The answer is the cells in their bodies, called melanophores and iridophores, found within a deep layer of their skin called the dermis. Melanophores are cells that contain melanin, the pigment in their (and our) skin that gives it its color. The melanin in the melanophores is able to condense and move up to darken the chameleon’s color, or disperse and move down to lighten it. Iridophores are cells that contain nanocrystals: these are transparent and made up of guanine, one of the four bases that make up DNA. The nanocrystals form a lattice which can become more loosely or densely packed as the nanocrystals move towards or away from each other. A tightly packed lattice reflects blue and green wavelengths of light, making it so these are the colors we see, while red and yellow wavelengths pass through the nanocrystals. A looser lattice does the
opposite, reflecting red, orange, and yellow wavelengths
while allowing blue and green light to pass through.
Now, why do chameleons change colors? Chameleons change color based mostly on their emotions, but maybe not in the way you’re thinking. They don’t change color to reflect anger, but to reflect a desire to mate or fight an opposing male, or as a sign of submission to those who may see them as a threat. In a relaxed state, the nanocrystals in a chameleon’s dermis form a tight lattice, so they appear green or brown. When they’re feeling excited, like when trying to fight off a competitor or attract a mate, the nanocrystals will move apart to form a loose lattice, showing off their brighter red and yellow colors. These bright displays can be a sign of strength, as weaker males tend to have duller colors. Speed and brightness of color change can often predict which chameleon will win in a fight (and the lesser opponent will often quit before the fight has even begun). When chameleons are feeling submissive, like trying to show that they are not a threat, they’ll turn a darker color.
This all isn’t to say that chameleons never change their color to camouflage themselves. However, some people believe that chameleons are able to blend into any background or pattern, which isn’t the case. Chameleons are able to make small adjustments in their color to adjust to their environment, like turning a darker shade of brown when light is lacking. They save the extreme color changes for mating and competition. The thing about chameleons is that they usually blend into their surroundings pretty well already, likely because this is their only defense mechanism. Chameleons lack traits such as sharp teeth or claws, venom, and speed. They must rely on being able to blend into their surroundings well to evade predators.
So, no, chameleon’s don’t really change their color to match their background, but they do change color to communicate to those around them (which I personally think is a lot cooler!). Perhaps Disney wasn’t so far off when they showed Pascal turning red with anger.