Tamar Stelling at the Washington Post:
He started with prawns. After so many years of working with them, he thought he knew what to expect, which was that he would see nothing more than reflex reactions. But to his surprise, when he brushed acetic acid on their antennae, they began grooming the treated antennae with complex, prolonged movements of both front legs. What’s more, the grooming diminished when local anesthetic was applied beforehand.