The ability to see color allows animals to better distinguish food, mates, and predators in their environment. The range of colors an animal can perceive depends on the types of photoreceptor cells in their eyes. Most mammals have two types of photoreceptors and can only see shades of blue and yellow. Birds, reptiles, amphibians, and fish often have more types of photoreceptors and can see a wider range of colors. But which animal sees the most colors? Let’s take a look at how animal vision works and compare the color ranges different species can detect.
How Animal Vision Works
Animals detect color through cells called photoreceptors in their eyes. Photoreceptors contain pigments that absorb light of different wavelengths, which our brains interpret as different colors. There are two main types of photoreceptors:
- Rods: Detect shades of gray and motion
- Cones: Detect color
Most mammals have two types of cones that allow them to distinguish blue from yellow. Humans, some primates, and a few other mammals have three cone types that permit the perception of red, green, and blue hues.
Birds, reptiles, amphibians, and fish often have four or more types of cones. The more kinds of cones an animal has, the more finely it can discriminate between colors.
Color Vision in Different Animals
Mammals
Most mammals have dichromatic vision, meaning they have two types of cones. With just blue and yellow cones, dichromats can’t detect red or green hues.
A few mammals have trichromatic vision with blue, green, and red cones. These include some primates like chimpanzees, orangutans, and humans. Trichromats see colors much as humans do.
Birds
Birds have excellent color vision thanks to their four cone types: red, green, blue, and ultraviolet. Their ability to see UV light allows birds to spot food, plumage markings, and predators better.
Some birds, like pigeons, may even have pentachromatic vision with a fifth cone type allowing them to see more colors than humans can imagine.
Reptiles
Most reptiles have tetrachromatic vision with four cone types. Many lizards and the dwarf crocodile have cones sensitive to red, green, blue, and UV light. Snakes often have receptors for green, blue, UV, and infrared.
This tetrachromacy allows reptiles to discern colorful patterns, choose mates, and locate prey.
Amphibians
Amphibians like frogs have rods and at least three kinds of cones. Most amphibians are tetrachromats with cones for red, green, blue, and UV light. Some frogs may even be pentachromats capable of seeing more complex hues.
Their color vision helps frogs find food and assists mating behaviors like displaying bright colors.
Fish
Many fish have tetrachromatic vision but others may have more cones. Goldfish are thought to have cones for red, green, blue and UV. Recent research found zebrafish can detect up to seven primary colors thanks to seven cone types.
Such broad color perception assists fish with finding food, avoiding predators, and communicating through colorful signals.
Which Animal Sees the Most Colors?
Of the major vertebrate groups, birds and fish stand out as having the widest color vision. Some birds likely see five primary colors while certain fish may distinguish seven or more spectral hues.
In particular, the zebrafish appears unique in its ability to see a range of colors beyond human vision. Zebrafish have cones sensitive to red, green, blue, and ultraviolet light, but also cones tuned to cyan, aqua, and crimson. This pentachromatic or heptachromatic vision allows zebrafish to make fine color discriminations in their environment.
Other fish like the goldfish and cichlids, some reptiles like chameleons, and a few birds such as pigeons may rival zebrafish in color perception. But the evidence to date suggests zebrafish edge out the competition in spectral sensitivity.
Conclusion
Animal color vision varies widely depending on the types of photoreceptors present in the eye. While most mammals see limited color ranges, many birds, reptiles, amphibians, and fish are tetrachromats with four cone types. Of these groups, birds and fish stand out for their enhanced color perception compared to humans. But zebrafish appear unique in having up to seven distinct cone types and the ability to distinguish the most colors in the animal kingdom.
