Seeing Colors!
When you wake up in a dark room, it seems that everything has disappeared. If you get up to go to the bathroom, you could trip over your shoes, or your backpack, or your dog. You could trip over a rhinoceros!
But maybe it's not totally dark. You keep your eyes open for awhile. In a few seconds you may be able to see some shapes - your desk, your backpack, and that big lump on the floor - your dog!
But you don't see colors in the dark - just black and white.
If you look out the window, maybe it looks like this!
Inside your eyes, there are two kinds of receptors (say: ree-sep-tor). A receptor is something that receives something.
One kind of receptor is called a rod. Rods see things in black and white. This is what the rods in your eye look like.
The other kind of receptor is called a cone. Cones turn light into color images.
The rods work when there's not much light, but the cones need more light. So when it's dark, just the rods are working and you see things in black and white.
Humans have lots of cones in their eyes, so humans can see a lots of colors. Other animals, for example, those that hunt at night, have more rods and fewer cones.
Want to see how dogs see? Click next!
