Why do crabs walk sideways?

Answer: Their leg joints bend sideways

Their leg joints bend sideways ✓ — Correct! Crab legs attach at the sides and have joints that bend best sideways. This body structure makes sideways movement most efficient. Some crabs can walk forward, but it's slower and awkward!

To move faster underwater — Wrong. Sideways walking isn't faster than forward movement. It's simply how crab anatomy works—their leg joints naturally bend in that direction.

Their shells block forward motion — Wrong. The shell doesn't block forward motion. Crabs walk sideways because their leg joints are designed to bend that way, making it their most natural gait.