Animal eyes have one big job in common, and that’s to collect light.
Animals, including you, must collect light to see. No animal can see in total darkness. Not even a cat can do that, even though some people think they can.
Animal eyes have many of the same basic parts for collecting light. First, they need a hole, or pupil, to let in the light. They also need a lens to focus it. Without a lens, images would be very fuzzy. Finally, eyes have a retina (RET-ih-na). That’s like a movie screen, because it’s where the light is projected. Chemicals in the retina turn the light images into nerve signals the brain can understand.
These parts make eyes the same, but what makes them different?
