How and why do chameleons change colors?

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   Richard Weiposted 10 years ago

   How and why do chameleons change colors?
   
   Believe it or not, animals can change their colors. Like many species such as octopuses, squid and cuttlefish, chameleons can change their colors. How do animals respond to natural environment? And why do they change their colors?
   
   

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   dashingscorpioposted 10 years ago

   I don't know (how) they change colors but I would imagine the purpose is to provide some means of self-defense from potential predators as they might appear to be camouflaged.

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      Richard Weiposted 10 years agoin reply to this

      Thank you.

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   connorjposted 10 years ago

   
   
   In the case of chameleon when calm it is a well camouflaged leafy-green; however, when agitated or anxious red, purple and yellows are reflected. Resent research explains that chameleons do not actually change color. Replicatable research by a group of biologists and physicists has concluded that instead of technically changing color the chameleon changes the spacing between cells which changes what (light) wavelengths are either absorbed or reflected. If a chameleon reflects the (blue) wavelength it appears blue in color...
   Recent research disproves longstanding beliefs about how chameleons change color. Previously, scientists thought that chameleons were able to change from green to yellow by dispersing different colored pigments through their skin cells. Instead what researchers found was that all of chameleons' colors—their resting green and agitated yellows and oranges are determined by changes in the way light reflects off the crystal structure of their cells.

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      Richard Weiposted 10 years agoin reply to this

      What do you mean by saying recent research? Could you please explain it?

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      connorjposted 10 years agoin reply to this

      Here is the reference.   
      www.nature.com/articles/ncomms7368
      by J Teyssier - ‎2015
      Mar 10, 2015 - Colour change and iridophore types in panther chameleons. .... We study the panther chameleon (Furcifer pardalis), a lizard from Madagascar, ...

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4. 75

   tsadjatkoposted 10 years ago

   
   
   Chameleons exhibit complex, rapid color changes during social interactions such as male contests or courtship.It is generally interpreted that these changes are due to dispersion/aggregation of pigment-containing organelles within dermal chromatophores. Chameleons shift color through active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores. In addition a deeper population of iridophores with larger crystals reflects a substantial proportion of sunlight especially in the near-infrared range. The organization of iridophores into two superposed layers constitutes an evolutionary novelty for chameleons, which allows some species to combine efficient camouflage with spectacular display, while potentially providing passive thermal protection.
   
   Many vertebrates can rapidly change color for camouflage, communication and thermoregulation, but these so-called physiological color changes are generally mediated by modifications of skin brightness (that is, diffuse and/or specular reflectivity) through dispersion/aggregation of pigment-containing organelles, especially melanosomes, within dermal chromatophores. On the other hand, rapid active tuning of skin hue has been described in only a handful of species and generally involves structural, rather than pigmentary, components, that is, multilayer nano-reflectors with alternating high and low refractive indices that generate interference of light waves. For example, some species of squid can rapidly tune skin iridescence through periodical invaginations of plasma membrane deep into specialized cells called iridophores, generating arrays of alternating cytoplasmic protein-rich lamellae and extracellular channels. In fish, amphibians and reptiles, iridophores containing transparent guanine nanocrystals generate a large variety of structural colors, and modifications of the multilayer reflector geometry has been suggested to generate color change in a few species. Finally, it must be emphasized that the color of a reptile skin patch is often the result of interactions among pigmentary and structural elements.
   Chameleons have two superimposed populations of iridophores with different morphologies and functions: the upper multilayer is responsible for rapid structural color change through active tuning of guanine nanocrystal spacing in a triangular lattice, whereas the deeper population of cells broadly reflects light, especially in the near-infrared range.
   Get it? Duh, what? :-)

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      Richard Weiposted 10 years agoin reply to this

      Many thanks for your wonderful answer!

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