Why Do Crabs Walk Sideways?

You see a crab at the beach, and it suddenly runs sideways across the sand. Not forward. Not backward. Only sideways.

It almost looks like it’s sliding instead of walking. You might wonder why it doesn’t just walk straight like a dog or a person.

Is it choosing to move that way, or is something different about its legs? What would happen if your own knees only bent sideways?

You start to notice how a crab’s body is shaped. And suddenly, sideways doesn’t seem strange at all.