I’ve always been fascinated by the ways in which different species of animals experience the world. I would love to be able to “borrow” my dog’s sense of smell for a while, feel with my cat’s whiskers, or echolocate like a bat. Don’t you think walking in an animal’s shoes, so to speak, for a day would help us understand why animals behave the way they do?
I recently listened to a segment of the show Radiolab that asked, “What do dogs see when they look at the rainbow? We humans see seven colors: red, orange, yellow, green, blue, and violet (ROYGBiV!). But as Thomas Cronin and Jay Neitz — two guys who study vision — explain, that's just a sliver of the spectrum. Along the way, we get some help imagining the rainbow from a choir, and we meet [a] little sea creature, who with 16 color receptors, blows the rest of us earthlings out of the water.” Check it out; the part with the choir is really cool.
I also just found a game that “offers everyone the ability to see through the eyes of animals you are familiar with. Based on proven scientific data, the intent is to teach both children & adults about animal vision: You are immersed into a 3D visual interactive simulation. And, to learn with fun, it includes also games for each animal, where players have to circumvent the constraints of animal vision to get the best score.”
The website describes the differences between visual abilities in a variety of species in the following way. Please excuse some of the awkward phraseology; the designers’ first language is French.
Human beings have a particularly sophisticated vision that allows them to see details very well, thanks to their highly efficient acuity. This feature exists because of the presence of the macula and the fovea in the human retina [areas that allow us to appreciate detail and perform tasks that require central vision such reading].
[Humans] are also trichromats which means that [we] can see all three fundamental and basic colors: red, blue and green.
Cats are dichromats. They do not perceive reds. Their visual acuity is very poor compared to humans because they do not have a fovea in their retinas.
On the other hand, their vision is particularly suitable for the tracking of movements with a wide 280° field of vision.
Dogs have somewhat the same vision as cats. They have a less broad field of less vision, but like their feline cousin, their eyes are equipped with a “tapetum lucidum,” a reflective membrane that allows them to absorb five times more light than humans and gives them an excellent night vision. This also makes their eyes shine at night.
Rats are myopic. Their vision is good up to 15 cm in front of their noses. After, it is a total blur. This is why we often see them move along the walls. This helps them to move and protect themselves.
Rats do not perceive colors at all. Their vision is more suitable for night vision.
Hawks are diurnal animals just like humans. They have very bad night vision and therefore remain in their nest to sleep. During daytime, their vision is excellent. Their eyes have a double fovea, which helps give them a much greater perception of details than human beings and incredible precision during flight. Hawks are also trichromats.
Bees’ eyes consist of a multitude of ommatidia — [almost like groups] of small independent eyes. Trichromats, bees can see from the three basic colors (red, blue, green) all the way into UV frequencies that enable them to distinguish more precisely some flowers. Their vision is more than ten times better than human performance.
So, if you are probably enjoying a little extra “family time” this week but running out of ideas to entertain the little ones (or the big ones, for that matter), check out the Radiolab segment and the All Eyes on Paris game and learn how animals see the world.
Dr. Jennifer Coates