• Frogs have a unique ability to see colour even when it is so dark that humans are not able to see anything at all, a new study has found.
• Researchers from Lund University in Sweden found that the night vision of frogs and toads appear to be superior to that of all other animals.
• Most vertebrates, including humans, have two types of visual cells located in the retina, namely cones and rods.
• The cones enable us to see colour, but they usually require a lot of light and therefore stop working when it gets dark, in which case the rods take over so that we can at least find our way home.

Photoreceptor cells

• It was previously known that toads and frogs are unique in having rods with two different sensitivities, leading researchers to hypothesise that frogs and toads might be able to see colour in low-light conditions.
• The researchers studied the frogs in a situation that is as serious as it is common, namely, when frogs need to find their way out in case they are trapped in conditions of complete darkness.