The crab will repeatedly rub the area of its body where it received the shock

Meanwhile, crabs have been known to repeatedly rub a spot on their bodies where they've received an electric shock.And even sea slugs flinch when they know they're about to receive a noxious stimulus.That means they have some memory of physical sensations.We still have a lot to learn about animal pain. As our knowledge grows,it may one day allow us to live in a world where we don't cause pain needlessly.