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?
These gridded crystals in the chameleons’ skin cells thus appear to act as a “selective mirror” to reflect only certain wavelengths of light, thus changing the chameleon’s color. These different crystal arrangements could, in theory, also work with the chameleon’s pigments to create even more colors, for example, combining a pigmented yellow with a reflected blue to make a bright green.
The biologists took this theory beyond the computer simulation by changing the distance between the crystals in skin cells in the lab. Cells dipped in salt water of varying concentrations swelled to varying degrees thus changing the spacing between the crystals. Their lab results reflected the predictions of the simulations.
Further bolstering the connection between the crystal spacing and the skin color changes is the fact that the female and young panther chameleons, which are not able to change color, do not have the special iridophore cells.
Now what about that second lower layer of cells with bigger, more disorganized crystals? The scientists believe this layer may act to reflect near-infrared light. While reflecting optical light can produce different observed colors, reflecting near-infrared light can act as a cooling mechanism by deflecting the sun’s rays.
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at firstname.lastname@example.org.