The ability to perceive color is vitally important in the animal kingdom. Color vision allows animals to find food, choose mates, avoid danger, and communicate with others of their species. But not all animals see color in the same way as humans do. So do any animals see in color? The answer is yes, many animals have some degree of color vision, but there is a wide variation between different species’ abilities.
Human Color Vision
Humans and some other primates have trichromatic color vision from three different types of cone photoreceptor cells in the retina. This allows them to perceive the full range of colors from red, green and blue light stimulation. The three different cones are maximally sensitive to short (blue), medium (green), and long (red) wavelengths of light. All other colors are seen by the relative stimulation of the three cone types. This advanced color vision evolved to help primates find fruits in dense foliage.
Animal Kingdom Color Vision Abilities
Many animals have dichromatic color vision from two types of cone cells. This is more common among mammals. Dichromats can distinguish blue from yellow and green hues, but cannot separate red and green. Fish often have even more rudimentary monochromatic vision from one cone type, limited to distinguishing color intensity and brightness rather than hue. However, some fish have up to five cone types and can see into the ultraviolet spectrum. Birds, reptiles and amphibians usually have tetrachromatic vision with four cone types sensitive to very short, short, medium and long wavelengths. This gives them an even broader color range than humans. Invertebrates like insects and cephalopods have varied types of color vision depending on their habitat and lifestyle requirements. So color perception abilities vary hugely throughout the different branches of the animal kingdom.
Mammals with Dichromatic Vision
Most mammals are limited to blue-yellow color vision from two cone types. These dichromats include important model organisms like rodents, dogs and cats. Cats have peak spectral sensitivities at 450 nm and 555 nm which gives them blue and green perception. Dogs have wavelength sensitivities at 429 nm and 555 nm, more achromatic than cats. Primates like humans split from other mammals around 60 million years ago and evolved a third cone type for trichromatic red-green color vision. Marine mammals like whales and dolphins also only have a single rod photoreceptor so are thought to be cone monochromats and effectively colorblind. So the answer to whether cats, dogs and other mammals see in color is yes, but only blue versus yellow hues.
Birds Have Superior Tetrachromatic Vision
Birds have four cone photoreceptor types with sensitivities ranging from red to violet, giving them an even broader color spectrum than humans can perceive. Their maximal responses are at 570 nm, 508 nm, 437 nm and 415 nm activated by red, green, blue and violet light respectively. Birds use their tetrachromatic vision for vital behaviors like finding ripe fruit, detecting predators, selecting colorful mates and marking territory boundaries. The cost of their visual acuity is that birds have very large eyes relative to their body size. Birds of prey have an even greater density of cone cells in their retina to spot small prey at a distance. The excellent color vision of birds shows that many animals do see a broader spectrum of colors than humans can.
Reptiles and Amphibians
Reptiles and amphibians also typically have tetrachromatic color vision but with sensitivities skewed towards the shorter wavelengths compared to birds. Turtles have cones maximally responsive at 630 nm, 525 nm, 435 nm and 365 nm detecting red, green, blue and UV light. The addition of a UV sensitive cone allows them to see into the ultraviolet range, invisible to humans. Many amphibians and fish also have UV receptors that males use to detect ultraviolet patterning in females during mating. The ability to see UV is very widespread in the animal kingdom but totally alien to human visual perception. Frogs can also adapt the sensitivity of their photo receptor cells depending on ambient light conditions. So reptiles and amphibians also commonly see in enhanced color compared to humans including UV hues.
Fish Color Vision Depends on Habitat
Fish exhibit a huge range of color vision abilities depending on what wavelengths of light are able to penetrate their aquatic environment. Shallow water fish are more likely to be tetrachromats with four cone types like zebrafish. But in murkier waters visual range narrows and fish become dichromats and monochromats. Marine fish living at greater depths can entirely lose their cone cells and retain only monochromatic rod vision. So a clownfish close to the surface perceives a vibrant reef in color, but a deep sea anglerfish is effectively blind to color, only seeing in black and white. The color vision of fish is adapted to their individual ecological niche. Cichlids who mate colorful males and drab females are usually trichromats similar to primates.
Invertebrates like insects and cephalopod molluscs display every possible type of color vision system. Grasshoppers are tetrachromats with photoreceptors peaking at 360 nm, 440 nm, 540 nm and 600 nm, an even broader range than birds can see. Bees are trichromats like humans, able to discriminate similar colors that are indistinguishable to dichromatic flower visitors. Dragonflies have as many as 11 types of photoreceptor and can potentially perceive UV, blue, blue-green, green, yellow, red and infrared light. Jumping spiders have eight photoreceptors covering 300–600 nm in 50 nm increments and expertly judge color to identify food sources. Cephalopods like octopuses and squid only have a single visual pigment but can perceive color through the whole retina and lens acting as spectral filters. So invertebrates display every gradation of color vision depending on their needs.
Marine Mammal Color Vision
Marine mammals like whales and dolphins are a special case, as they have lost most of their cone photoreceptors in favor of a dim-light sensitive rod-only retina. Rod cells sacrifice color perception for superior low light vision. This makes sense for aquatic mammals hunting in the ocean depths where color information is unavailable. As whales and dolphins retain only vestigial non-functional cone cells they are effectively cone monochromats and so completely colorblind. Their vision is similar to red-green colorblind humans who only have two functioning cone types. So while fish and invertebrates display every imaginable type of color vision, marine mammals have almost none due to their unique environment.
In conclusion, many animals do have color vision, often superior to humans, but their visual abilities are finely tuned to their ecological requirements. Primates, birds and some reptiles, amphibians and fish evolved trichromatic or tetrachromatic color vision to enhance their ability to spot food, mates and predators. Meanwhile, marine mammals sacrificed color perception entirely in favor of dim light vision. And invertebrates display huge variety in their visual systems. So most animals have some degree of color vision, but there is huge variation between different species and habitats. Understanding animal color vision gives us insight into their sensory worlds and how they experience a richer visual environment than we do.