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How come owls see at night?
Question Date: 2006-03-16
Answer 1:

Owls are very interesting animals. In general, their eyes are like ours. Here's how they work. Light comes into the pupil of the eye and is picked up by receptors at the back of the eye. Some complicated things happen, and then nerves carry information about the light to our brains. The brain makes sense of the information and we see an image.

Let's go back to those receptors. There are two major kinds and we have both. Rods only let us see black and white, but they work really well even if the light is very dim. Cones let us see color, but only work well when it's pretty light. You may have noticed that if you look at things when it's sort of dark, you only see shades of black and gray.

Owls have good night vision for a few reasons. First, they have a lot more rods and not as many cones, so they lose color vision, but see a lot better at night. Also their eyes are very large, so they pick up a lot of light rays.

Owls have a sort of mirror at the back of their eye called the tapetum lucidum. When light goes past the rods and hits the mirror, the light is reflected back at the rods. This means the owl gets 2 chances at catching each bit of light. When you shine a light at an animal at night and their eyes seem to glow, you know they have a tapetum lucidum. You might be wondering why we don't have this, since it seems so useful. The drawback is that it makes what you see slightly blurry, so animals that are active in the daytime don't have them.

There are some owls that are active during the day. Do you think that they have the same kind of eyes as owls that are active at night?

Thanks for asking,

Answer 2:

Owls primarily hunt mice and other rodents. Rodents are most active at night, so owls need to see in the dark in order to hunt their prey. Owls have several adaptations which allow them to see well at night. First, owls have very large eyes for their body size. Large eyes let in more light than small eyes. In addition, their pupils can expand greatly at night, enhancing their ability to see in the dark. Inside of an owl's eyes, there are a large number of structures called rods. Rods are sensitive to light, so a large number of rods help owls see at night . Humans also have rods, but we have a much smaller number than owls have. As a result, owls see 35 to 100 times better than humans can in dim light. Here is a link to a website which provides more information: more info

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