How Do Chameleons Change Color?

Chameleons boast some of the brightest colors seen in nature. They can also go from a subdued green to bright red in a matter of minutes. So how do they do it?

Sabrina Stierwalt, PhD
4-minute read
Episode #147

Hi I’m Sabrina Stierwalt, and I’m Everyday Einstein bringing you Quick and Dirty Tips to help you make sense of science.

Chameleons stand out among the lizard species for their uniquely shaped heads, their very long, fast-moving tongues, and their distinct long, thin feet.  Due to the subset of chameleons that can change color, they have also long been used in literature, music, and the arts to represent characters that alter themselves according to their surroundings. As Boy George once sang, “Karma chameleon, you come and go.”

For decades, biologists thought chameleons were able to change color using pigments in their skin. However, new research shows that pigments are only a small part of the process. To understand how chameleons are able to transform from bright greens to purples, blues, and oranges and back again, we must first understand how prisms work.

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What is a prism?

A classic prism is a triangular box made of glass or plastic sides that is used to reflect or refract light. Prisms can be used to separate white light into its constituent parts, or in other words, into the separate colors that combine together to make the white light, a process called dispersion. But how do you break apart a beam of light?

Light always travels at the same (finite) speed … in a vacuum, that is. Once light has to travel through another medium, like glass or water, it has to slow down. Light of different wavelengths, or colors, like blue versus red light, will then have slightly different speeds.


About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.