We have all heard about that old dog being colour blind, or lemmings jumping off a cliff (remember that old video game from 1991?). But is there substance behind these claims?

People falsely believe cats and dogs can only see black and white. In all animals, including humans, the perception of colour is determined by the presence of cells in the eye, called cone photoreceptors. Cats and dogs have two kinds of cones, which are sensitive to blue and green light. This means they have a useful level of colour vision. Humans have three types of cones (sensitive to red, blue and green light).  Since cats and dogs only have blue and green cones, they have a much more muted perception of colour, which is akin to colour blindness in humans. The only animal that is confirmed to see in black and white is a fish called a Skate. This is because it has no cones in its eyes.

Cats and dogs do have more ‘rods’ – the light-sensing cells in the eye – than humans do, so they can see better in low-light situations. Which is why they never stub their toes in the dark ...

Lemmings do not commit mass suicide. This particular myth is based on some actual lemming behaviour. Lemmings have large population booms every three or four years. When the concentration becomes too high in one area, a large group will set out in search of a new home. Lemmings can swim, so if they reach a water obstacle, they may try to cross it.

Inevitably, a few will drown (but this is not suicide!). No one knows exactly when the myth started, but a 1958 Disney video White Wilderness, which won an Oscar for best documentary feature, has emerged as the most likely suspect. The ‘documentary’ was faked. The lemmings supposedly committing suicide by leaping into the ocean were actually thrown off a cliff by the Disney filmmakers.

And finally, being as blind as a bat means not being blind at all. While many bats use echolocation to navigate, all of them can see.