We humans long assumed that our visual system stood at the top of evolutionary success. Our knowledge of colour vision was primarily based on what humans see: researchers easily performed experiments on colour perception in humans. Although scientists obtained supporting information from a variety of other species by recording the firing of neurons, we remained unaware until the early 1970s that many vertebrates, mostly animals other than mammals, see colours in a part of the spectrum that is invisible to humans: the ultraviolet. In fact, the discovery of ultraviolet vision began with studies of insects conducted by Sir John Lubbock, who discovered sometime before 1882 that in the presence of ultraviolet light, ants would pick up their young and carry them to dark areas or to areas illuminated by longer wavelengths of light. In the mid-1900s, Karl von Frisch and his students showed that bees and ants not only see ultraviolet light as a distinct colour but use ultraviolet in skylight as a compass. The finding that a great number of insects perceive ultraviolet light misleadingly gave rise to the idea that this spectral region provides a private sensory channel that avian predators like eagles and vultures cannot see. Nothing, however, could have been further from the truth. Subsequent research showed that birds, lizards, turtles and many fish have ultraviolet receptors in their retinas.