Sight, hearing, and smell each give you a different kindof information about your environment.Sight resultswhen your eyes detect light waves reflected from every tinybit of an object's surface.Hearing depends on your de-tection of sound waves coming from things that are vibrat- ing rapidly near you.Smell alerts you to gases called va- pors that are in the air around you.
In one situation, one sense may be helpful; another sense may help in a different situation. Sound waves bend around objects. As a result, you can hear around corners .Light waves, on the other hand, do not bend as much as sound waves. So, if danger is coming toward you from behind, you may not see it. But you can hear it, if it makes a noise.
When sight and sound do not give you infomation in a situation, smell may give you a message.A great many substances are either vapors or give off vapors. These vapors enter the nose and stimulate special cells there that give rise to impulses. 8 Your brain interprets these impul-ses as odors.
There are uncounted thousands of different odors.However, every vapor does not give off odors. Can you smell air or water vapor? You may think you can, but actually you smell something in the air or water. Why is it an advantage to be unable to smell air or water?
Almost all animals give off detectable vapors and recog- nize each other by scent. An animal parent may reject its offspring if the young animal has been handled by a human being and does not have its usual scent.
Some animals rely more on scent than on sight and sound. When a lion smells a deer, it knows food is near. And although the deer may stay out of sight and make no sound, still, it can't hide its scent from the lion.Odor leaves its trace for a while. The lion can smell the deer and trace it by its scent.
Picture an antelope watching for food and on the lookout for danger. 10 His large nostrils sniff the air. His cone-shaped ears move quickly this way and that to catch sound waves. His wide-spread eyes search all directions for a sudden movement.
Many animals like the antelope continually make use of all three senses.
