Anyone who’s watched a movie like Tangled, or any other cartoon featuring a chameleon, has likely asked: How do chameleons change color? The short answer: crystals (nanocrystals, to be precise).
However, it wasn’t until recently that scientists discovered this astonishing and fascinating fact about chameleons’ color-changing abilities.
Until 2015, scientists believed that chameleons changed their color by changing the pigment in their skin, the same way as octopuses. Octopuses have a lower layer of skin cells that contain redistributable melanin granules. This lower layer has branches that extend up into the other layers of cells, thus enabling the octopus to change its color by redistributing melanin to the upper layers.
This theory is perpetuated to this day even by sources like Encyclopedia Britannica.
But if this isn’t how a chameleon changes its color, then it begs the question:
How Does a Chameleon Change Color?
Cells & Nanocrystals
All animals have pigmented cells that reflect light in order to express color. Chameleons have a transparent outer layer of skin cells that contains yellow pigments called xanthophores and red pigments called erythrophores.
Beneath this outer layer of skin cells is another layer that contains cells called iridophores. This layer is where the magic chameleon color change happens.
Contained within each iridophore is an intricate lattice-like arrangement of nanocrystals that are capable of reflecting back a broad spectrum of colors.
“[I]ridophores have the ability to absorb or reflect any and all colors of the spectrum.” (Source: The Science Times)
How Do Chameleons' Nanocrystals Reflect the Spectrum of Colors?
When the nanocrystal lattices tighten into closer patterns, they reflect back the shorter light wavelengths of darker colors like blue, and absorb the longer light wavelengths. When the lattices expand further apart, the nanocrystals reflect back colors with longer light wavelengths like red, and absorb the shorter light wavelengths.
The ability to tighten and expand these lattices of nanocrystals is how chameleons are able to change their color.
So, what is a chameleon’s “natural” color?
When a chameleon is in a relaxed state, the nanocrystal lattices of its iridophore cells are somewhat tighter. They actually reflect back blue light! That blue light passes through the yellow xanthophores pigments of the chameleon’s outer layer of skin cells, thus manifesting as green.
“If the crisscross pattern is tight, we’ll usually see blue. But as light travels through the chameleon’s skin it may hit those tiny mirrors and bounce through some yellow pigments in the layer above. As it does this, we see green. … If the crisscross pattern of particles is looser, we’ll usually see more red. If the red passes through the yellow layer above, we’ll see more orange colors.” (Source: Ask Dr. Universe)
Chameleons also have a third layer of crystal-bearing cells beneath the iridophore layer. The crystals in this layer are larger, more spaced out, and more disorganized. The cells in this layer reflect the longer wavelengths in the infrared part of the spectrum, and are believed to help regulate the chameleon’s body temperature.
Now that you know how chameleons change color, let’s talk about why chameleons change color.
Why Does a Chameleon Change Color?
Chances are, you think chameleons change color to blend into their surroundings and hide from predators and other potential threats – chameleon camouflage, effectively.
It’s an understandable misconception. The myth of chameleon camouflage has been circulating for years. And our favorite cartoons do nothing to dispel this myth.
The truth is, chameleons don’t need to change colors to camouflage themselves. Their natural, or relaxed, colors are typically green and brown with distinct stick- or leaf-like patterns. This natural state helps them blend in almost perfectly with the trees they hang out in.
Chameleons are also quite fast, and prefer to run away from predators and other threats. If they use their color-changing abilities as chameleon camouflage, it’s as a secondary means of defense.
So if chameleon camouflage is a myth, the question remains: Why do chameleons change colors?
Scientists have identified two primary reasons that chameleons change colors:
- To communicate
- To regulate body temperature
Chameleons Change Color to Communicate
Just as we humans use language to communicate our thoughts and feelings to one another, chameleons use their color-changing abilities to communicate different things to other chameleons.
They may change color to:
- Start a fight
- Admit defeat
- Show relaxation or stress
- Exhibit excitement
- Scare off a predator
- Attract a mate
- Indicate illness
Female chameleons have more limited color-changing abilities than do males, and their colors tend to be duller.
What colors a chameleon can change to depend both on its gender and what species of chameleon it is. The chart below is meant to be a basic guide to help you better understand your particular chameleon.
Chameleon Color Chart
Green or Brown
Bright Red, Blue, Yellow, and Green
Aggression/Ready to Fight
Dark Black, Brown, or Other Dark Colors
Illness, Stress, or Fear
Red with Black Stripe
Brumation or Basking
Although male chameleons will turn brighter colors to indicate their readiness to fight, the loser of the fight will dull his colors to indicate defeat and submission. It’s not uncommon for one chameleon to go dull even before engaging in a fight with his opponent.
When seeking a mate, male chameleons will turn bright and vibrant reds, blues, yellows, and even white to impress a female and indicate an interest in mating.
Females, on the other hand, may turn brown or white to indicate a lack of interest in mating. Or she might change her color to gold, blue, and bright green to show her interest in mating. And if she’s already pregnant, she’ll let the male suitor know by turning dark green and yellow.
Chameleons Change Color to Regulate Body Temperature
The other reason chameleons change color is to regulate body heat.
Like other lizards, chameleons are cold-blooded, and therefore incapable of creating their own body heat. They rely on their environment, especially the sun, to keep their bodies at just the right temperature.
Unlike other lizards, however, chameleons can tighten the nanocrystal lattices of their iridophore cells to turn their color darker and absorb more heat from the sun. And if they start to get too warm, they can expand those nanocrystal lattices to change a lighter color and reflect the suns heat out of itself.
Takeaway: Chameleons change color by controlling the nanocrystal lattices of their iridophore cells. These nanocrystals reflect back different light wavelengths, thus giving expression to different colors.
Your chameleon needs a wide variety of highly-nutritious, gut-loaded insects as the main staple of its diet. The Dubia roaches offered by Dragon’s Diet are a great start to keeping your chameleon well-nourished, happy, and living its best life.