India, Dec. 10 -- If you drive through the desert and spot a bright orange bearded dragon stretched across a tree stump, don't expect the colour to last. Take a few steps closer, and the orange quickly fades. The body darkens. Within seconds, the lizard blends into the ground instead of standing out against it.

That shift is not for show. It is a basic survival tool, and one reason reptiles continue to draw scientific interest.

Researchers at the University of Melbourne say colour change helps reptiles in several ways. Camouflage protects them from predators. Brighter tones can signal territory or warn rivals. Darker shades help absorb heat, which is crucial since reptiles depend on sunlight to warm their bodies.

But the ability to cha...