BRAINDUMP
How come some animals can change colour?
Li Wu
Flatfish take only a few seconds to change colour to blend with their background. Many other animals change colour to communicate. Chameleons are very good at this. They change to express sexual interest, readiness for a fight and to hide from predators. Some chameleons also change colour to help maintain their body temperature. Cuttlefish are masters of rapid colour and texture changes, meaning they can ‘disappear’ against their background as well as communicate complex messages. Their skin can change colour so rapidly that they produce waves of colour, controlling both the speed and detail of the patterns they can produce. Frogs generally don’t change colour like this, though a few tropical species change colour as chameleons do to maintain a constant temperature.
Some animals change very slowly to match a seasonal change in their surroundings, simply by moulting and then growing different coloured hair. The rapid changes, however, are achieved with ‘chromatophores’ in the skin. In cuttlefish, there are tiny pockets of pigment such as melanin. These pockets are like pixels on an LCD screen. Simply by expanding or contracting these ‘pixels’, they can create almost endless blends of colours and patterns at will.