In Class Activity - The World Through Someone Else's Eyes
Time: This activity will take 20 - 30 min. to complete.
Kit # 60
This activity was created by Mike Tveten, biology instructor at Pima's Northwest Campus. Thanks, Mike!
Of all our sensory structures, our eyes are perhaps the ones we rely on most. In this lab, we will try to experience what life might be like for some other types of animals by trying to see through their eyes.
If your own vision is compromised, you may not be able to do some of these activities. If that is the case, come up to the front desk in the lab for assistance.
Your textbook describes the structure of the eye in several types of animals. But have you really thought about what vision in these other animals must be like? Let's try to experience it for ourselves. Go and get Kit #60, and bring it back to your desk.
Seeing through the eyes of a flatworm
Flatworms have very primitive eyes. In fact, they really aren't eyes, just eyespots. As the figure (to the left) shows, the eyespots have a layer of pigment that activates photoreceptors. These eyespots don't produce an image like our eyes do, but rather just detect the presence of light. Since flatworms need to stay moist, and since they need to avoid predators, they use their eyespots to help them get away from light. The eyespots are oriented in such a way that if the light is bright and equally intense in both eyespots, the source of the light must be straight ahead. Likewise, if the light is dim but equally intense, the light is behind them and they are heading toward darkness.
Let's see what it is like to be a flatworm. In your kit, you will find a flashlight. Turn on the flashlight, close your eyes, and shine the flashlight on your face. When your eyelids are closed, your eyes are functioning like the eyespots of a flatworm. Try moving the flashlight around with your eyes still closed -- Hold the flashlight about two feet (arm's length) away from your head, and move the flashlight from far left to straight ahead to far right. With your eyes closed, can you tell the direction of the light? Could you find your way to darkness with your eye's closed?
Answer these questions on your worksheet:
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