Ever tried to see in colour, in the dark?
But Frogs can!
Uniquely frogs have shown an ability to see colours at extremely low light levels, even until they reach the limit of their night vision. This is thought to be an animal kingdom first and its function in frog ecology can only be speculated. Frogs may communicate at different times using colours, when breeding for example, and as many frog species are highly active under low light, perhaps this is why an enhanced colour night vision is essential. Tropical forest dwelling species in particular have diversified under the low light conditions beneath the canopy layers. This suggests that perhaps the unique vision is in fact a significant protagonist to the evolutionary success of all frogs.
It has long been understood that the rod cells of the frog retina has two types of sensitivity. In all other animals with rod cells, they simply react only to light intensities and so result in the typical night vision we experience, gradient and shape. It may be that rod cells in frogs can in addition, detect colour, gradient and shape. This novelty could be of some significance to medical researchers who want to investigate solutions and develop treatment for people suffered with failing vision.