There is a misconception about chameleons that they change their color in order to blend in with their environment.That is actually not the case.When a chameleon is calm it is green and so it naturally blends in with its leafy surroundings.But male chameleons change color when they become excited in the presence of a female or a rival male,as shown here.
人们一直误以为,变色龙是为了在环境中隐身,事实并非如此,变色龙在冷静时是绿色的,因此也就自然而然的融入到绿意盎然的环境中,但是 当周围出现雌性或是另一只雄性竞争者时雄变色龙就会变色 就像图里这样.
I will put the first frame in the bottom right for comparison.As you can see,as he becomes more excited.his color changes to be more yellow orange and red.So instead of blending in this chameleon will now stand out.But how do chameleons actually change their color? For years we thought that there was a simple well-established mechanism for this color change.
右下角放一只变色龙作为对照,你睢 当它牠变兴奋时，颜色会更橙、更红些，这只变色龙不再隐身 变醒目了，变色龙到底是如何变色的？多年来 我们一直认为，这种变色龙过程是一种简单的固定机制.
In their skin,chameleons have different cells containing colored pigments.Some are yellow others are red and some contain the dark melanin pigment.Many animals including chameleons are known to turn a darker shade by causing the melanin to spread out along the fingery extensions of the cell.They turn lighter again by condensing the pigment back into one spot.
变色龙的皮肤里，含有不同颜色的细胞，有些黄的 有些红的，还有一此含有黑色素，我们知道许多动物 包括变色龙，在体内黑色素沿着指状细胞分散时，此肤会变黑，当色素被压缩回原点时皮肤又会变白.
It was assumed that chameleons must turn yellow,orange and red in the same way,by causing those pigments to spread out in those cells.But new research from collaborating groups of physicist and biologists at the University of Geneva shows that this is incorrect.Now the first clue should come from the fact that there is actually no green pigment in the a chameleon.The green color actually created by two distinct mechanisms,pigment color and structural color.
Beneath the yellow pigment cells,there are cells containing tiny 130 nm crystals regularly arranged in a lattice.Now light diffracts off these crystals and due to the spacing between them,blue light constructively interferes and is therefore strongly reflected.Whereas the other colors are not reflected.This is very similar to how a morpho butterfly wing creates an iridescent blue.
There is no blue pigment just the periodic nanoscale structure that acts as a strong reflector for only one color.So a chameleon looks green due to the combination of the yellow light from the pigment plus the blue light reflected off the crystal structure beneath it.So how do chameleons change this green into yellow orange and red?Well previously it was assumed that the color change was achieved by dispersing pigments in the colored cells.
But now scientists have found it's actually the crystals underneath which are changing.By increasing the spacing between the crystals the chameleons can change which color is selectively reflected.Bigger gaps between the crystals are better at reflecting longer wavelengths.So as the spacing increases,the color changes from blue to green to yellow,and then orange and red.
但是 科学家发现变色的原因，其实是内层晶体结构发生了变化通过改变晶体的间距，变色龙可以调整反射光的颜色，晶体间距增大，则可以反射波长较长的光，因此 随着间距变大，颜色就会从蓝到绿 再到黄，然后是橙色、红色.
Scientists compared skin samples from calm green chameleons and excited yellow chameleons and found that indeed,in the excited chameleon the crystal spacing was much further apart.Here you can see a single cell enlarged and the color it reflects changing from blue to green to yellow,orange and red.
Plus,a computer simulation of the light reflected off crystals while their spacing is decreasing also provides excellent agreement with these observations.Furthermore,applying physical pressure to the skin causes the crystals to compress and so they reflect more blue.When that pressure is removed,the crystals expand again reflecting more green light.
另外 通过计算机模拟，晶体间距变大对光线反射的结果，也跟观察结果相一致，此外，通过物理挤压皮肤进而压缩晶体间隙，也可以使其反射更多蓝光，当压力解除，晶体间隙恢复 会反射更多绿光.
The structure of a chameleon's skin gets even more fascinating,as there is another layer of cells underneath which also contain crystals.But these crystals are larger more spaced out and more disorganized.This means they reflect longer wavelengths in the infrared part of the spectrum and they reflect a broader range of these wavelengths.It's thought that the function of this layer could be to reflect light from the sun since these chameleons live in bright full-sun habitats.
So male chameleons don't change their color by spreading out red and yellow pigment.Instead they do something much more remarkable.They actively tune the spacing between nanoscale crystals in order to create structural colors that span the whole length of the visible spectrum.Now what I find amazing is that in this day and age we thought we had the answer to how chameleons change color,but it actually took the combined expertise of physicists and biologists working together to figure out what's really going on.
因此 雄性变色龙并通过，扩散红色和黄色色素进行变色，它们的做法更高端大气，是通过调整纳米级晶体，对横跨整个可见光谱的光波进行反射 以此构造出结构色，令我吃惊的是 如今 在我们自以为了解变色龙变色奥秘之时，却发现 在结合物理和生物两门专业知识后，我们方才真正解开变色龙变色的奥秘。