Most humans see the world in a brilliant array of colours. Human vision, however, is not exactly the standard throughout the animal kingdom. Many animals are blind to certain colours we see, while there are other colours animals see that we cannot even imagine. Let’s check out a few interesting animals and the way they perceive colour.
Animals like dolphins, whales, and seals are marine mammals — they live in the ocean but breathe air and bear offspring like humans. These animals have only one type of cone, the photoreceptive cell that we use to see colour (we have three types). As a result, marine mammals are totally colourblind, seeing all colours as black, white, or a shade of gray. To help picture this, think of how the world looks at night under a full moon: You can see shapes and shading, but no colour.
Most mammals that people keep as pets, including dogs, cats, rabbits, and mice, as well as farm animals like cattle, are partially colourblind. Dogs have two types of cones, and as a result they can distinguish blue, yellow, and green. They cannot distinguish red or orange from gray. Sight for these animals is similar to sight for people who are red-green colourblind. They see some colours, and the colours they cannot distinguish blend in as if they were ordinary grays. This explains why red-green colourblindness in humans can pass undetected for a long time—unless you are talking to others about colour and realize that an object looks different for you, the world looks perfectly normal to you even if you are partially colourblind.
There are certain colours animals see that humans cannot see; birds and insects in particular have a wider visual spectrum. Most birds have four types of cones, while pigeons have five. The type of light picked up by birds that people cannot see is ultraviolet (or UV) light — the rays that cause sunburn. Insects, including bees, can also see ultraviolet. Flowering plants have evolved patterns in ultraviolet colours that guide pollinators like bees and hummingbirds into their flowers. This helps the animals to find food and the plant to produce seeds; pollinators’ ultraviolet vision and flowers’ ultraviolet patterns appear to have coevolved for this specific purpose, though it is unclear which species evolved first.
Not only do animals see different colours, but they also see in different ways, such as heat-sensing snakes and the echolocation of bats. Animal vision is neat!