Fish pain: A painful topic

Abstract

If fish cannot feel pain, why do stingrays have purely defensive tail spines that deliver venom? Stingrays' ancestral predators are fish. And why do many fishes possess defensive fin spines, some also with venom that produces pain in humans? These things did not evolve just in case sentient humans would evolve millions of years later and then invent scuba. If fish react purely unconsciously to " noxious " stimuli, why aren't sharp jabbing spines enough? Why also stinging venom? Key (2016) seems an excellent neurobiologist, but he is less convincing as a logician. He launches with the seemingly inarguable truism that to address whether fish can feel pain, " it is necessary to first understand the neural basis of pain in humans, since it is the only species able to directly report on its feelings. " But no logic supports this conflation of pain and human speech.