There is a huge amount of variety in the colours and patterns exhibited by plants and animals. However, most of this variation is fixed at the individual level; only when comparing individuals do we see differences. The ability to change your colour during your lifetime is a trait possessed by only a few animals, which have converged on remarkably similar mechanisms. Colour changes that occur during an animal’s lifetime can occur slowly, with seasonal changes or age (morphological colour change). More dramatically, and more interestingly, some species also have the ability to change their colour or pattern very rapidly, in response to environmental or social conditions (physiological colour change).