Education:Science Projects: The Eyes Have It

Let's look at our eyes.

Humans have muscles in their eyes. When we want to see something on either side of us, we don't have to turn our heads to look at it–we can simply move our eyeballs to the side and see what is going on.

Not all animals have these muscles in their eyes. Owls cannot move those magnificent big eyes. If an owl wants to see something off to the side of its head, it needs to turn its head from side to side. Owls do have an excellent sense of sight, and they also have a layer of reflecting cells at the back of their eyes, so that the light passes through the eye twice, allowing them to see in dark areas better. Owls are nocturnal, but their excellent sense of sight helps them see and hunt at nighttime, when most humans are asleep.

Here are two fun experiments you can try.

Experiment #1

You will need your eyes.

1. Sit with your head facing forward.

2. Keep your head straight but look up, only using your eyes.

3. Now close your eyelids but still keep looking up.

4. Try to open your eyelids now. What happened?

You cannot open your eyelids while looking up. We use the same muscle to look up that we use to open our eyelids! Pretty neat, huh? Ask an owl to do that experiment. What do you think would happen? Nothing at all. Owls don't speak English (or French, or Spanish, or any human language).

Experiment #2

Sometimes our eyes play tricks on us. This is called an "optical illusion." Magicians take advantage of these optical illusions to play tricks on us. Here is an easy optical illusion you can try at home.

What you need

  1. An empty toilet paper roll
  2. Your eyes

What you do

It looks like there is a hole in your hand. Is this true? Nah, it is merely an optical illusion.

Happy science!

Catch Dr. Zoolittle in an entertaining show in the San Diego Zoo's Children's Zoo daily during the summer and every weekend and school holiday.

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Animal Bytes: Owl