Octopuses can solve complex puzzles and show a preference for different individuals, but whether they, and other animals and invertebrates, have emotions is being hotly debated and could shake up humans' moral decision-making, says an expert in animal minds. Most countries don't recognize invertebrates, such as octopuses, crabs, lobsters and crayfish, as sentient beings that can feel pain, but the United Kingdom is considering amendments to its animal welfare legislation that would recognize this.