What's up with the colors of Chameleons, they come and go. Changing
color is a rarity in the animal world, and also a mystery, until now! Hey
everybody thank you for reading today.
I'm Trace and I am right here on our brand new set! Chameleons change
color so well, and are so well known across the planet for doing so, that their
name is synonymous with someone who is good at changing their look, behavior or
opinions as their situation changes.
Most people think chameleons change color for camouflage, but that's not
it at all! Only the males can change color, and they do so to communicate danger
to other nearby chameleons, or for a mating display. Ladies.
*wink*It's a pretty dramatic show when a chameleon swaps its green for
bright red, and thanks to new research, we now know HOW they do it. Researchers from the University of Geneva looked
at the skin cells of chameleons to observe how they change color. Within their skin, it turns out, chameleons
have cells called iridophores. Suspended
within those cells are tiny guanine Nano crystals which are formed into a
lattice. When relaxed, the chameleons’
iridophore lattices are contracted, and mainly reflect blue light, but when
excited the chameleon expands and three dimensional lattices expand along with
them, reflecting different wavelengths of light! Below that layer, there's a
layer of skin with even larger Nano crystals which reflect near-infrared light;
providing "passive thermal protection." Which is great, because these
cold-blooded animals can't change their body temperature; changing that base
layer may be one way they can affect how much near-infrared light, and
therefore heat, is absorbed into their body,. Camouflage is also called cryptic
coloration; or a color and pattern that makes an animal difficult to discern
from its surroundings; concealing it.
The ability to CHANGE colors isn't unique to chameleons -- some fish,
frogs, insects, crustaceans, cephalopods, and other lizards can do it too, but
they don't have Nano crystals… this research is the first time that's been seen
in reptiles. And other animals use
different methods of color shifting. Cuttlefish, for example, can also change
their colors at will; but rather than crystal-filled iridophores, they use
chromatophores. Chromatophores are sacs
of a single pigment of color surroundedby muscle. The cuttlefish has learned to widen or constrict
that sac to show more or less of that color.
Invertebrates like cephalopods use these chromatophores too, and for
more on that you can check out our video exploring how the disco clam can
reflect light like a disco ball! Over time, evolution, mutation and simply
breeding with others can cause changes in the colors of species, humans
included -- all blue-eyed humans descend from a single mutated ancestor. Usually because those animals which have
these colorful adaptations tend to survive better. Zebra stripes confuse predatory eyes, helping
to disguise individuals and making the herd look more massive; background
matching camouflage helps both predators like tigers blend with their
environment; as well as helping their prey hide by resembling its surroundings…but
these adaptations take many generations to develop! Active color change is
pretty rare in the Animal Kingdom.
Before this research, scientists believed chameleons changed color the
same as cuttlefish or octopuses, but once they put the skin cells into a
super-magnifying electron microscope, they were able to see this unique and
super cool system for reflecting light! How do you think humans camouflage into
our surroundings? Do we? Why or why not. . .
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