FLORIDA PANTHER At night, panther eyes appear to glow from moonlight reflected off an iridescent membrane in the retina. Humans require six times more light to see. “Jerky motions of prey shift panthers into hunting mode,” says Jill Mellen of Disney’s Animal Kingdom. |
Morning on my sister's Illinois farm. my eyes open and I am surrounded by other eyes. Three people, one dog, four cats. We all have predator's eyes—forward facing with binocular vision—and move to the kitchen, where breakfast is prey. We humans, with our very color-sensitive eyes, are searching the cupboard. The Folger's coffee jar is bright red so we can find it fast. The little collie mix's round pupils are searching out breakfast, too, by following the human motions. It can see yellow and blue but can't tell red from green. The barn cats slink along the counter. Their vertical pupils, constricted ovals in the daylight, scan a 287-degree field of vision for the kill. It comes when the opener pierces the little round can.
We are also wired to adore and protect any face with what the Germans call kinder schema—the flat faces, snub noses, and big eyes of a human infant. A baby’s eyes take up about a third of its entire face. In adults, they take up a fifth. In fact we’re born with nearly adult-sized eyes. Our faces just grow up around them.
The big-eyed kinder schema is the appeal of that puppy in the window, or the kitten your kid brings home. Big eyes, or pronounced eyes, reach out. At an animal shelter a light-colored animal, peering out with big dark eyes, will almost always find a home before the black one, whose eyes, like those of my sister’s Angus, disappear into their body.
ROCKHOPPER PENGUIN Penguins have poor binocular vision and must tilt their heads laterally to look up or down. During dives, a special membrane protects their eyes underwater. “A translucent eyelid closes,” says Anita Schiavoni-Gibbons, maven to a colony of 69 Rockhoppers at SeaWorld Adventure Park, Orlando. |
Now I would rather walk on glass than address the scientific debate on animal consciousness. I only know that if you grow up among and around all kinds of animals, as little farm girls do, you know in your heart that you can tell what they are thinking, when you look at them, and they look at you. When I was a girl, I shot a ruby-crowned kinglet with a BB gun. It died in my hand. Its eyes died last and I never shot a gun again.
I have a comrade in world-renown wildlife photographer James Balog, who brings to these pages, from his just released book, Animal, some powerful eyes of the wild. In his book, Balog writes, “Animals are whole unto themselves, completely poised in an existence bequeathed by five billion years of evolutionary rhythm, their minds and spirits focused. To look into the eyes of many animals, particularly the big ones like bear and elephant, is to sense a degree of calm and certainty rarely felt in people.”
Peregrine falcon Peregrine visual acuity is four times greater than that of humans. And they see fast. “Their eyes have to compensate as they dive at speeds of up to 200 mph at prey, “ says Bill Burnham of the World Center for Birds of Prey in Boise, Idaho. |
Balog believes that his stylized portraiture yielded an enormous dividend. “It led me into the secret labyrinth of the animal mind, revealing that intangible yet unmistakable force called consciousness.”
My own thinking about animal eyes probably goes back to February nights in the 1950’s, when 1, the oldest daughter of a father with no sons, would stand in the barn and help midwife piglets into the world. I cleaned them up, rubbed them down, got the “stuff” out of their mouths. But it was when their eyes opened that they were, to my eyes, really there.
Two kinds of eyes rule in the animal kingdom: directional eyes, which only sense light, belong to worms and other bitty creatures. Image-forming eyes are found in certain mollusks, bi-valves, most arthropods and nearly all vertebrates. The biggest image-forming peepers belong to cephalopods—such as the Pacific Octopus with its grapefruit-sized eye or the Giant Squid with eyeballs bigger than basketballs.
BABY ORANGUTANS Orangutans, like humans, judge distance well because of good binocular vision. When you look into their eyes, says Mike Bates of the San Diego Zoo, “they seem more pensive than the other apes. You see the eyes sparkle. The cogs are turning.” | 
MANDRILL In threatening situations, the red-and-blue faces of mandrills brighten and they make direct eye contact in an attempt to scare their nemeses off. If that fails, they close their eyes, revealing frightening white eyelids, and open their mouths wide to show 4-inch canines. |
How our eyeballs sit in our heads is also important. The Tarsier, an Asian night monkey, has eyes so big, that they don’t move at all in their sockets. So like owls, they turn their whole heads to look around. At the other end the gecko, with its eyes on stalks, can hold its head still and swivel its eyes around like periscopes. Our own eyes are special because while protected in our skull’s sockets, they’re surrounded by a lot of sclera—the whites of our eyes—which lets our pupils range freely up, down and all around. If we had only a little sclera, like say a dog does, when we looked sharply to the side we’d only see the insides of our skulls.
The whole business of color vision, species, by species, is murky and controversial. We have 125 million thin straight rods that see in black and white, and seven million fat little cones that examine colors in bright light. It’s believed that various animals have various combinations of these. Primates and mongooses have pretty good color vision. Dogs and cats so-so.
| GIANT PANDA Left: Black patches around small eyes make them appear larger and give giant pandas a fierce visage in confrontations with other pandas. “Ironically, this same characteristic endears pandas to humans because we’re drawn to animals that have large eyes,” says Ron Swaisgood of the San Diego Zoo. ASIAN ELEPHANT Right: Elephants can’t see much past 100 yards, but their eyes are well protected for the task of foraging in thick undergrowth. The eyeballs recede under eyelids as strong as vise grips. “Elephants sometimes appear to weep, but that’s because they have an abundance of fluid lubricating a nictitating membrane that helps keep the cornea free of debris,” says Alan Roocroft of the San Diego Wild Animal Park. |
And owls have no cones, so they see only in black and white. Bees can see a color past violet that we cannot see, but they can’t see red. Ants can’t see red. Hummingbirds like red best. And prairie dogs have some color vision but can’t tell red from green. What color vision means to animals is tricky science, because while we can examine the comparative anatomy of eyes, it’s much more complicated to determine how an individual species’ central nervous system and brain interpret what the eye sees. Suffice it to say that we homo sapiens are the only group who finds it necessary to stand around the paint chip section of Home Depot for two hours on a Saturday morning.
WYOMING TOAD High-rise eyes set off to the sides allow the nearsighted Wyoming Toad a wide field of vision to scan for insect prey. “They don’t have to se anny farther than their tongues can reach—a couple of inches,” says Joseph Collins of the Kansas Biological Survey. |
I’d probably give the award for most versatile eye to the Oak Toad, which, as it swallows, moves its eyeballs back into the roof of its mouth to help push food down his throat. The most useful adaptation goes to the Burrowing Mole Skink, which has a little picture window in his eyelid so it can look around without opening its eyes. And the Homed Toad, when angered, can squirt blood from its eye into its enemy’s face.
The worst eyesight for an animal its size belongs to the rhinoceros, which at 15 feet can’t tell a man from a tree. They will repeatedly charge large rocks. If you want to see how a Rhinoceros sees, squint way down until your eyelashes are woven together, then look around.
Of course compared with the possum that lives under my front porch back home in Washington, D.C., the rhino could probably read the New York Times.
Which brings me home to my “city” farm. Here, in the morning, my eyes also open to other eyes. Dog eyes. Cat eyes. Like their rural cousins, they only know the hunt for the can opener and little round cans. Crow eyes and even chickadee eyes. The squirrel, with its eyes on the sides of its head like all prey animals, sits on the air conditioner and stares at me — sideways with just one big eye, until I put out some peanuts. If I’m slow, he stares harder.
And I am thankful for my excellent human vision, and that the Folger’s jar is red and I can find it right away.
For more about the science behind color vision, see the Color and Vision Database at the Color and Vision Research Laboratories at the University of California at San Diego, www-cvrl.ucsd.edu.
To learn more about nocturnal vision in animals, see
www.pbs.org/wgbh/nova/ leopards/nightvision.html.