It looks like you have already thought about this. You are right that some people are called "color blind," but most of these people can see some colors, and not others. A lot of men and boys have trouble telling the difference between red and green. My cousin can't tell the difference between dark red and black. So not everyone sees colors the same, but it can be hard to tell when someone can't see color.

In kindergarten or first grade, most of us learned the color names. Maybe you and I learned to call a certain color "green" but we may have actually "seen" different colors.

Lots of animals don't see color the way we do. That's because they have eyes that are adapted for seeing at night. What animals are out at night? These are nocturnal animals. They probably see little or no color. Why would some animals need to see color?