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Photonic crystals cause active colour change in chameleons
Jérémie Teyssier1, Suzanne V Saenko2, Dirk van der Marel1
1Department of Quantum Matter Physics, University of Geneva, Geneva 1211, Switzerland.
Nature Communications
|March 11, 2015
Summary
Chameleons change color by actively tuning guanine nanocrystals in their skin, not pigment dispersion. This unique two-layer iridophore system allows for camouflage and vibrant displays, with potential thermal benefits.
Area of Science:
- * Structural coloration and biophysics
- * Evolutionary novelty in reptile physiology
Background:
- * Chameleons, especially panther chameleons, display rapid and complex color changes during social interactions.
- * Previous hypotheses attributed these changes to pigment organelle movement within chromatophores.
Purpose of the Study:
- * To investigate the physical mechanism behind chameleon color change.
- * To analyze the role of dermal iridophores in color modulation and light reflection.
Main Methods:
- * Microscopy and photometric videography.
- * Photonic band-gap modeling.
- * Analysis of guanine nanocrystal lattices in dermal iridophores.
Main Results:
- * Chameleons actively tune guanine nanocrystal lattices in superficial iridophores for color shifts.
- * A deeper layer of iridophores with larger crystals reflects near-infrared sunlight.
- * This dual-layer iridophore structure is an evolutionary novelty in chameleons.
Conclusions:
- * Color change is achieved by structural tuning of nanocrystals, not pigment dispersion.
- * The superposed iridophore layers enable combined camouflage, display, and thermal protection.
- * This mechanism represents a significant evolutionary adaptation in chameleons.
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