Amazing Eyes of the Animal Kingdom

By
NEW YORK—While the human eye can do some very impressive things, our eyes are by no means the best of the best or even the most interesting. With phrases like “Birds-Eye View,” “Hawk Eye” and “Eagle Eye” there’s no doubt that some eyes of the animal kingdom are capable of amazing feats. However, while other species like starfish might have less capable sight, their visual capabilities have fascinated scientists for decades. In some of Vision Monday’s past Today’s Reads we’ve covered fascinating animal eyes before whether they’ve been goats or sharks, so why stop a good thing. There are so many species in the world that can do the unthinkable with the help of their vision. Let’s take a look at some of these interesting eyes.



Birds

  • Eagles (as well as other birds of prey) can see four to five times farther than the average human.

  • An eagle’s retinas are more densely coated with cones than human retinas and have a deeper fovea, a cone-rich structure in the backs of the eyes of both humans and eagles that detects light from the center of our visual field.

  • Many birds also see colors as more vivid than humans do and can discriminate between more shades and see ultraviolet light.

  • Owls have eyes that are shaped like tubes and are held rigidly in place by bones called sclerotic rings. Because of this, owls have to move their entire head to get a good look around since their eyes are held in place.

  • Owls are very farsighted and compensate by having sensitive whisker-like bristles around their beaks to help them detect objects at close range.

  • Additionally, owls have great binocular vision compared to other birds, giving them increased depth perception.
Amphibians

  • Frogs have large protruding eyes that are set far apart to give them an almost 360 degree view of their surroundings, helping them spot potential predators and prey.

  • Frogs have a third eyelid that covers their eyes so they can keep them open underwater. The eyelid is called the nictitating membrane and also helps the eyes to stay moist when they are not in the water.

  • Toads have glands behind their eyes that can secrete a burning milky toxin.
Sea Creatures

  • Starfish have eyes, one on the end of each of their arms.

  • A blue sea star’s eyes lack lenses.

  • The image formed in the eye of a starfish is a very crude image and only has about 200 pixels.

  • The chiton, a mollusk, has eyes that are made of the mineral aragonite.

  • Chiton vision is about a thousand times courser than human vision, and it's likely they see only in black-and-white.

  • The hard rock-like aragonite is extremely resilient, an important trait for chitons, which are constantly being pummeled by waves in the shallow tidal pools they live in.
Now that we’ve learned a little bit about the amazing eyes of the animal kingdom, head to National Geographic to see if you can correctly identify these animal eyes.