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Learn more about animals!

Unless someone like you cares a whole lot, nothing is going to get
better, it's not.
- Dr. Seuss, The Lorax

KidsCorner - Eyes

THE EYES HAVE IT

The eyes of animals have developed differently based upon the requirements of the lives they lead. The pupils of an animals’ eye tells a lot about the life it leads. An eye’s pupil is the opening through which light passes enabling an animal to see. The eye needs a certain amount of light to be able to see properly. The job of the pupil is to open and close to adjust for the amount of light coming into the eye. Pupils expand or open up when it is dark. This allows the needed amount of light to enter the eye. Pupils contract or get smaller when the light is bright which lets in only the light needed for vision and keeps out too much light which could harm the eye. This is why we squint our eyes when we go from indoors to the bright outdoor sunshine.

Humans’ eyes are designed to work best in daylight but are good for seeing details close up and far away. Humans’ eyes have a round pupil. The human’s round pupil contracts to a tiny pinhole in bright light and opens in a wide circle in low light. Carnivores like cats, have eyes that work very well at night when there is not much light at all. Their eyes are good for detecting movement and for picking out their prey against a background of grass or trees. Cat’s eyes have a pupil that opens to a round circle in low light but contracts to a vertical (up and down) slit in bright light. Herbivores, animals like goats, sheep, cows, and horses that eat only plant material, have eyes that work well in daylight and at nighttime. Because herbivores are the prey of many carnivores, their eyes are good for both detecting movement and for picking out objects on a vertical plane. Their eyes have evolved to be able to spot a predator on a wide horizon. Their eyes have pupils that are shaped like a rectangle and are positioned horizontally (left to right).

Look at the eyes below and compare the pupils of each. See if you can distinguish the differences and identify which eye belongs to a cat, to a human, and to a goat.

The goat, with its horizontal rectangular pupil is on the left. The human with its circular pupil is in the middle. The cat with its vertical slit pupil is on the right.