Sentience means having the capacity to have feelings. This requires a level of awareness and cognitive ability. There is evidence for sophisticated cognitive concepts and for both positive and negative feelings in a wide range of nonhuman animals. The abilities necessary for sentience appear at a certain stage in humans, as in other species, and brain damage can result in those abilities being lost so not all humans are sentient. Sentient animals include fish and other vertebrates, as well as some molluscs and decapod crustaceans. Most people today consider that their moral obligations extend to many animal species. Moral decisions about abortion, euthanasia, and the various ways we protect animals should take into account the research findings about sentience.