There’s an idea circulating that humans are the only animal to experience sexual pleasure; that we approach sex in a way that is distinct from others. As with many questions about sex, this exposes some interesting facts about the way we discuss the subject. On one level, the question of whether humans and nonhumans experience sex in the same way is fairly simply dismissed: how would we know? We cannot know how a nonhuman experiences anything – they can’t be asked. Sex as an experiential phenomenon for nonhumans is, quite simply, inaccessible. Science is obliged to propose questions that are answerable, and “how does a leopard slug experience sex?” is, at time of writing, about as unanswerable as they get.