The perception of color
Color matters to all us human beings. Without it, life would be pretty dull. In the human eye, there are light receptors which send messages to the brain. Isaac Newton made the discovery that color is not inherent in objects. It is the surface of objects that absorb some colors and reflect others. What we perceive as color, then, is reflected back to us. So when we see things that are blue, for instance, the color blue has been reflected and the other colors in the spectrum have been absorbed.
For human beings, the visible spectrum for humans falls between ultraviolet light and red light. Research says that humans are able to distinguish up to some 10 million colors. The retina of the eye has two kinds of cells that detect and react to light. These are called rods and cones. These are the light receptors, or photoreceptors, that are sensitive to light. Rods react when you are in dim light and cones move into action when you are in bright light. In cones, there are photo pigments. These have molecules that can detect color. Each kind of cone is sensitive to different visible light wavelengths.
In certain animals that see color, color detection works in much the same way as it does in humans. Some animals have only a few kinds of cones, so they can detect only a few colors. The mantis shrimp can see more colors and things that are blue, than all the other creatures in the animal kingdom. Though a lot of animals may not see as many colors as we do, they see in different ways than we do. The disadvantages that they have with color perception is made up by advantages in their visual fields. For example, dogs and cats do not have as many color receptor cones as we do, but they have more rods. As a result, they can see better at night than we do. Here is an insight into the animals that can see blue things.
Dogs and cats
These are the most coveted domestic animals and everyone loves them as pets. It is a myth that they are colorblind. Animals that are truly colorblind, don’t have any cones at all, whereas dogs and cats do possess them. Dogs and cats may not have a wide range of color detection, but their visual fields are greater than humans’ are. Human beings have three photo receptor cones in the eyes, dogs only have two. They don’t have the cones that detect the color red. So they don’t see as many colors as we humans do. Nonetheless, they do see things that are blue and yellow. This is true for cats as well.
Bees and butterflies
We humans often brag about how we are able to see a whole lot of colors that other creatures can’t. We should stop right there! Humans have only three receptor cones, whereas some animals have much more in this respect. Butterflies and bees, those insects that adore flowers, have four kinds of color receptor cones. You won’t believe how many colors they can see in the color spectrum!
What’s more amazing is, that besides all the shades of blues and other common colors, they can see ultraviolet hues too! A bee may see a blue flower, because biologically, it needs to. Nonetheless, many types of flowers have patterns that are ultraviolet, mainly on their petals. Bees and butterflies can then target the areas of a flower that they need to zero in to suck nectar. These insects may have these extra photoreceptors as a way to see other animals of prey that are blue, or any other color. It acts to ward off predators.
If you ask a fisherman whether a color is important to use as bait while catching fish, he will probably say that it is. There is scientific evidence to suggest that color does play a role in attracting fish. Fish have been in water bodies for more than 450 million years. They are remarkable aquatic creatures that have made several adaptations to survive in water. It is a difficult task to live in a marine ecosystem, but fish have excellent sensory capabilities and can detect predators. They have a much better sense of smell than we do too.
Water, nonetheless, presents somewhat of a challenge for fish regarding vision and color. Light alters itself as it moves through water. First, we have to understand that what we humans see as color is only a part of the whole story. Out of the total electromagnetic radiation that is received from the sun, we only see what is called the visible spectrum. Colors that exist within the visible spectrum depend on the wavelengths of light. Longer wavelengths are red and orange, whereas shorter ones are blue, violet and green.
Many fish can see all things that are blue, and many other colors that we cannot see. They can also perceive ultraviolet. Nonetheless, scientists say that a minimum level of light is required for a fish to detect color. Many fish also detect colors that they are used to seeing. Nearshore fish can see more blue, so their eyes are adapted to see more of that hue. Blue is also the last color to be absorbed by fish, so they can see it clearly, even in deeper water.
Avian creatures, birds, have much better overall visual acuity than most other creatures. Birds are tetrachromats. That means that they see four colors. These are, namely, blue, green, red and ultraviolet. So, yes, they can definitely see the color blue. Ornithologists explain that birds can see a whole spectrum of colors that are not even visible to us human beings. For example, to us humans, the North American Songbird looks the same, whether it is a female or a male. Nonetheless, within the species, males can detect females and vice versa, by the colors of their feathers.
Owls can see the color blue well, among other colors. This is true for owls because, like the North American Songbird, it helps to detect genders and find mates. Though they see the color blue just fine, they tend to have worse color vision than eagles and hawks. There are several bird species that are blue, and other birds need to be able to detect the color for mating purposes. Patterns of blue feathers also need to be deciphered by birds to ward off predators.
Some other animals
Mice, rats and rabbits don’t have good color vision. They have a limited amount of cones, and can only see greys and some yellows and some things that are blue. Bulls attack the red cape, not because it is red, but because it is moving. Bulls don’t see blue or any other color. Monkeys and ground squirrels see color, and the color blue, but their color vision isn’t as good as human beings. It is better than dogs’ and cats’ vision, though.
Crustaceans and cephalopods
Crustaceans, like crayfish, lobsters, and crabs, can see the color blue, and red too. Cephalopods can see blue only. These are octopi and squids. This can be explained because of the amount of rods and cones present in the eyes of these creatures.
Apes and chimpanzees can see a fair amount of color, and things that are blue. The configuration and amount of rods and cones in their eyes is similar to that of a human being. Nonetheless, this is not true for all primates. For instance, the South American monkey can see blue, but not red. Other mammals, such as elephants, can see violet, blue, yellow and green, but not red.
Blue color vision at night
In human beings, cones which are color and bright light receptors, stop working at night. Or they work less. With the function of the rods in our eyes, we still see, but mainly shades of gray. In the evolutionary way of life, this makes sense for human beings, but animals are required to have color vision at night.
For example, consider the gecko. The gecko’s eyes have evolved to be so sensitive, that they are 300 times more sensitive than human eyes. Geckos don’t possess rods at all. Instead, the cones in their eyes have evolved so that they take on the function of rods. They are longer shaped and more sensitive overall. A gecko can see the color of blue things in the day and at night. Elephant hawk moths see blue at night, as well as other colors, as do several species of lemurs that are nocturnal. They see blues and greens as they need to detect fresh leaves with high amounts of protein at night. Elephants are more sensitive to blue and violet shades at night, besides seeing these in daylight. Lions can see the color blue and green in the daytime as well as at night.
In the animal kingdom, this is the king of color sight. The mantis shrimp has sixteen color receptor cones, compared to the meager three we humans have. It can perceive ten times more color than a human, and clearly more than any other animal on earth. The mantis shrimp can not only see things that are blue, but can also see ultraviolet, infrared and light that is polarized. Another unique fact is that they can move each eye independently of the other, as each eye is affixed on a separate stalk!