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Chameleons : Color Changing Alchemists



(veiled chameleon)


We recently posted a lizard dissection video (which you can check out here), where we explained the anatomy and physiology of an anole lizard. However, anole lizards are only one of hundreds of species of lizards, and they are arguably one of the least interesting. I mean just look at chameleons!


Chameleons are a clade of old world lizards (the clade consisting of 202 species), and although they are characterized by many unique features such as highly modified extrudable tongues, swaying gait, and zygodactylous feet, the anatomical marvel they are best known for is none other than their ability to change colors. Chameleon species are able to change the color (& pattern) of their skin into any combination of black, brown, green, blue, yellow, pink, red, orange, green, purple, turquoise, and more.


Most people incorrectly assume that chameleons change the color of their skin as a means of camouflage, when in fact color change has very little function in camouflage for most chameleon species. Research shows that color change mostly functions in social signaling and as a response mechanism to changes in temperature and other environmental conditions. Many chameleon species have been observed having brighter coloration when displaying anger or aggression to other chameleons, and darker coloration when they are submitting or ‘giving up’ to another chameleon. And since chameleons are ectothermic (meaning their regulation of body temperature relies on external sources), they turn into a lighter color to reflect heat and lower body temperature (when the weather is hot), and turn into a darker color to absorb heat and raise body temperature (when the weather is cold).


Although scientists initially thought that the mechanism behind chameleons’ color change was the dispersion of pigment-containing organelles throughout the body, research has proven that this pigment dispersion model has little relevance in the color changing mechanism. Turns out chameleons have multiple layers of skin, the outermost layer being transparent, and each subsequent layer containing specialized cells called chromatophores. Chromatophores are cells that contain pigments, and what’s fascinating is that each layer of chameleon skin has chromatophores that contain different kinds of pigment. These pigments are usually closed away in tiny sacs within the cells, but when a chameleon goes through a mood/temperature change, the nervous system orders specific chromatophores in a certain layer of skin to expand/contract, changing the color of the cell, and in turn the color of the entire organism. The chameleon is able to achieve its vibrant array of coloration by varying the activity of the different chromatophores across its numerous layers of skin.


Now, after reading this, you might be jealous of these fascinating lizards that can change into any color of the rainbow. However, did you know that over a third of the world’s chameleons species are currently endangered due to habitat loss? We can all agree that the world would be significantly less interesting without these fascinating critters, so let’s all try to combat habitat loss by conserving water/energy, spreading awareness, and donating to conservation organizations.


(chameleon changing color)




Sources:

https://www.wired.com/2014/04/how-do-chameleons-change-colors/

https://www.livescience.com/50096-chameleons-color-change.html

https://www.nationalgeographic.com/animals/2018/08/chameleon-camouflage-color-change-myth-news/


Photo credit: https://wall.alphacoders.com/big.php?i=503155

Vid credit: https://www.youtube.com/watch?v=ioblgpA5eTo

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