十万个为什么·科学阅读30篇（1）

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变色龙如何改变体色？

Chameleons don’t change color to match backgrounds exactly—they shift hues mainly to communicate or regulate body temperature.
Special skin cells called chromatophores contain pigments like yellow, red, and brown, which expand or contract under nervous control.
Beneath them, iridophores reflect light using tiny guanine crystals that rearrange to alter wavelength interference.
Cooler temperatures cause crystal lattices to tighten, reflecting shorter blue wavelengths; warmth spreads them to reflect longer red ones.
Males often brighten during mating season, while stress or illness may trigger dull, dark tones.
Recent studies show some chameleons even adjust brightness independently of hue for better camouflage in shade or sun.
Robotic engineers copy this layered optical system to develop adaptive camouflage materials for sensors.
Unlike octopuses, chameleons rely less on vision feedback and more on internal hormonal and thermal signals.