"In any case, abundant evidence indicates that all invertebrates with a brain can experience pain. Like vertebrates, numerous invertebrates produce natural opiates and substance P. These animals include crustaceans (e.g., crabs, lobsters, and shrimps), insects (e.g., fruit flies, locusts, and cockroaches), and mollusks (e.g., octopuses, squids, and snails) [...] Also, crustaceans, insects, and mollusks show less reaction to a noxious stimulus when they receive morphine. For example, morphine reduces the reaction of mantis shrimps to electric shock, praying mantises to electric shock, and land snails to a hot surface."