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Chameleons' Color-Changing Secret Revealed By Laura Geggel, Senior Writer March 10, 2015

The chameleon's uncanny ability to change color has long mystified people, but now

the lizard's secret is out: Chameleons can rapidly change color by adjusting a layer of

special cells nestled within their skin, a new study finds.

1. very strange and difficult to explain

2. if something mystifies you, it is so strange or confusing that you cannot understand or explain it

3. a type of reptile that has four legs and a long tail

4. to move into a comfortable position, pressing your head or body against someone or against

something soft

Unlike other animals that change color, such as the squid and octopus, chameleons

do not modify their hues by accumulating or dispersing pigments within their skin

cells, the researchers found. Instead, the lizards rely on structural changes that affect

how light reflects off their skin, the researchers said.

1. if something disperses or is dispersed, it spreads in different directions over a wide area

2. a natural substance that makes skin, hair, plants etc a particular colour

To investigate how the reptile change color, researchers studied five adult males, four

adult females and four juvenile panther chameleons (Furcifer pardalis), a type of

lizard that lives in Madagascar. The scientists found that the chameleons had two

superposed thick layers of iridophore cells — iridescent cells that have pigment and

reflect light. [See photos of color-changing chameleons

1. a type of animal, such as a snake or lizard, whose body temperature changes according to the

temperature around it, and that usually lays eggs to have babies

2. relating to young people who are not yet adults

3.a large wild animal that is black and a member of the cat family

The iridophore cells contain nanocrystals of different sizes, shapes and organizations,

which are key to the chameleons' dramatic color shifts, the researchers said. The

chameleons can change the structural arrangement of the upper cell layer by relaxing

or exciting the skin, which leads to a change in color, they found. For instance, a male

chameleon might be in a relaxed state when it's hanging out on a branch, and in an

excited state when it sees a rival male.

1. a person, group, or organization that you compete with in sport, business, a fight etc

"When the skin is in the relaxed state, the nanocrystals in the iridophore cells are

very close to each other — hence, the cells specifically reflect short wavelengths,

such as blue," said study senior author Michel Milinkovitch, a professor of genetics

and evolution at the University of Geneva in Switzerland.

On the other hand, when the skin becomes excited, the distance between

neighboring nanocrystals increases, and each iridophore cell (which contains these

nanocrystals) selectively reflects longer wavelengths, such as yellow, orange or red,

Milinkovitch told Live Science in an email. But chameleons aren't always blue. The

lizards' skin also contains yellow pigments, and blue mixed with yellow makes green,

a "cryptic" color that camouflages them among trees and plants, Milinkovitch said.

1. having a meaning that is mysterious or not easily understood

2. a way of hiding something, especially soldiers and military equipment, by using paint, leaves etc

to make it look like the things around it

This male chameleon changed color, from green to yellow. Its red markings also became more vibrant. 1. things painted or written on something

2. full of activity or energy in a way that is exciting and attractive SYN lively Hong Kong is a vibrant,

fascinating city.

The "red skin hue does not change dramatically during excitation, but its brightness

increases," the researchers wrote in the study.

Furthermore, the researchers found a deeper and thicker layer of skin cells that

reflect a large amount of near-infrared sunlight. While these cells do not appear to

change color, it's possible that they help the chameleons reflect heat and stay cool,

the researchers said.

The researchers used a number of methods to study the iridophore cells. They filmed

the chameleons' color changes using high-resolution videography and made

numerical models that predict how the nanocrystals should reflect light.

"The results are a perfect match with what we observe [in real life]," Milinkovitch

said.

The researchers also manipulated the cells by subjecting them to solutions of

varying concentrations, which caused the cells to swell or shrink. These

modifications changed the distances between the nanocrystals, and altered their

visible colors, just as the researchers predicted they would, Milinkovitch said.

1. to make someone think and behave exactly as you want them to, by skilfully deceiving or

influencing them

2. subject somebody/something to something phrasal verb, to force someone or something to

experience something very unpleasant, especially over a long time

3. BIG to become larger and rounder than normal – used especially about parts of the body →

swollen

4. to become smaller, or to make something smaller, through the effects of heat or water I’m

worried about washing that shirt in case it shrinks.

However, only adult male chameleons change color, especially when they see a rival

male chameleon they want to chase away, or a female to attract, Milinkovitch said.

Females and young chameleons are dull-colored and have a very reduced upper layer

of iridophore cells, he said.

The findings may help engineers and physicists replicate the chameleon's color-

changing capacities in new technology, such as appliances that eliminate reflection,

Milinkovitch said.

The study was published online today (March 10) in the journal Nature

Communications.

Why and How Chameleons Change Their Color

The color-changing ability of chameleons has always intrigued human beings. We

often think how cool and easy life would be if we could change our colors, blend in

with our surroundings, and camouflage ourselves just like a chameleon can do. It

would definitely help us out of any awkward situations!

1. very interested in something because it seems strange or mysterious

2. to become combined in this way

3. a way of hiding something, especially soldiers and military equipment, by using paint, leaves etc

to make it look like the things around it

4. making you feel embarrassed so that you are not sure what to do or say

Many of us believe that a chameleon changes its color to camouflage itself. However,

as it turns out, this is one of the most common and false myths that people believe.

1. to happen in a particular way, or to have a particular result, especially one that you did not expect

2. an idea or story that many people believe, but which is not true

Why Does a Chameleon Change its Color?

A chameleon changes its color to adjust its body temperature to that of the outside

temperature. A cold chameleon will turn dark to absorb more heat, while a hot

chameleon will turn lighter in shade in order to reflect the heat from its body. Also the

change in color in a chameleon can indicate its mood. An angry chameleon will have a

darker color, whereas a chameleon in a relaxed mood will have a lighter color.

A chameleon, upon seeing a rival, changes its color to darker shades in order to

assert its dominance. On the other hand, a lighter color is used to attract potential

mates.

How Does a Chameleon Change its Color?

Chameleons have a special type of cells called chromatophores. They are able to

manipulate these cells in order to change their color. A chameleon has two

superimposed layers within its skin, and the upper layer consists of nanocrystals of

different sizes. A chameleon changes its color by changing the size and shape of these

nanocrystals.

When a chameleon is in a relaxed state, the nanocrystals in the skin are closer to each

other and they reflect shorter wavelengths, like blue and green. When a chameleon is

excited, the distance between nanocrystals increases and it reflects longer

wavelengths, such as red, orange and yellow.

This color-changing ability is not the only unique thing about chameleons. They can

also look in two different directions at the same time.

Wow! Isn’t that cool? Don’t you wish that you had these unique features that every

chameleon enjoys?

How Do Chameleons Change Colors?

Chameleons are famous for their quick color-changing abilities. It's a common

misconception that they do this to camouflage themselves against a background. In

fact, chameleons mostly change color to regulate their temperatures or to signal

their intentions to other chameleons.

Since chameleons can't generate their own body heat, changing the color of their

skin is a way to maintain a favorable body temperature. A cold chameleon may

become dark to absorb more heat, whereas a hotter chameleon may turn pale to

reflect the sun's heat.

Chameleons will also use bold color changes to communicate. Males become bright

to signal their dominance and turn dark in aggressive encounters. Females can let

males know if they're willing to mate by changing the color of their skin. Owners of

chameleons can learn to read their pet's mood based on the color of its skin.

So how do they pull off these colorful changes? The outermost layer of the

chameleon's skin is transparent. Beneath this are several more layers of skin that

contain specialized cells called chromatophores. The chromatophores at each level

are filled with sacs of different kinds of pigment. The deepest layer contains

melanophores, which are filled with brown melanin (the same pigment that gives

human skin its many shades). Atop that layer are cells called iridophores, which have

a blue pigment that reflects blue and white light. Layered on top of those cells are

the xanthophores and erythrophores, which contain yellow and red pigments,

respectively.

Normally, the pigments are locked away inside tiny sacs within the cells. But when a

chameleon experiences changes in body temperature or mood, its nervous system

tells specific chromatophores to expand or contract. This changes the color of the

cell. By varying the activity of the different chromatophores in all the layers of the

skin, the chameleon can produce a whole variety of colors and patterns.

For instance, an excited chameleon might turn red by fully expanding all his

erythrophores, blocking out the other colors beneath them. A calm chameleon, on

the other hand, might turn green by contracting his erythrophores and allowing

some of the blue-reflected light from his iridophores to mix with his layer of

somewhat contracted yellow xanthophores.

With these layers of cells, some chameleons are capable of producing a dazzling

array of reds, pinks, yellows, blues, greens, and browns. These bold statements won't

help them blend into the background, but they will allow them to get their message

across to other chameleons loud and clear.