I don’t know about you, but I thought to
be chameleon-like was to be someone who could
fit in anywhere.
Adapt.
Blend in.
Turns out that is all wrong.
Chameleons don’t change color to match their
environment.
In fact, it’s just the opposite.
Their baseline is camouflage.
When chameleons are relaxed, they’re mostly
green.
They naturally blend into their home in the
forest canopy.
They even mimic leaves by dancing around a
little.
But when they feel threatened, or annoyed,
or just want to show a little swagger – that
is when their color changes.
They transform into living mood rings.
Chameleons change color to make a statement.
The faster their skin changes colors, the
more excited they are.
How do they do this?
Well it turns out we’ve been getting that
wrong too.
Until this year, scientists thought chameleons
change color by spreading out pigments in
their cells, like the skin of the squid we’re
seeing right here.
But the truth is way more complex.
Just below the surface of their skin is a
layer of cells called iridophores.
These cells contain tiny, nano-scale salt
crystals.
They’re only a 130 nanometers across – that’s
less than one hundredth of the width of a
human hair.
The crystals are arranged in a three-dimensional
lattice.
When light hits the lattice, it shatters into
different wavelengths.
Some are absorbed and some bounce back.
The result, to our eyes, appears green or
red or blue.
The wings of the Morpho butterfly have similar
structures, which reflect brilliant blue hues.
But unlike Morpho butterflies, chameleons
can stretch or contract the lattice, which
moves the distance between crystals.
Each of these points of light is an array
of crystals.
When the distance changes, the crystals reflect
a different wavelength of light.
The result is a dramatic shift in color.
So what if we could come up with some kind
of material that could change from one brilliant
color to another?
Electrical engineers at UC Berkeley are trying
to do that.
To mimic a chameleon’s structural color
control with synthetic materials.
They arranged tiny, nano-scale silicon ribbons
on a sheet of flexible plastic.
Each one of these “pixels” is made up
of about 160 ribbons.
When the plastic stretches, the space between
the ribbons becomes greater and a different
wavelength of light is reflected – just
like chameleon skin.
Well, almost.
This synthetic chameleon skin has just one
layer of nano-scale arrays.
The salt crystals in real chameleon skin are
stacked in several layers, which makes their
skin some of the most colorful and complex
in the animal kingdom.
They produce colors that aren’t even visible
to human eyes.
What I like about chameleons is they show
us how wrong we can be about science.
What we called “camouflage” is an entire
language… as alien to us as the clicks of
a dolphin or the low rumble of an elephant.
A visual language … made of colors we can
only begin to imitate and imagine.
