Take our quiz to find out. National parks provide habitat for 600 or so threatened and endangered species, and wildlife viewing is one of the top reasons people visit parks. What rare, charismatic ...

Quiz: What animal does each eye belong to? Imagine a startled pigeon flying at your head. Your eyes—and brain—allow you to see this obstacle quickly, without thinking, and to duck (if you're lucky).

We don't know exactly when the first animals on Earth appeared, but it's thought to be around 700 million years ago. Around ...