Do worms feel pain and are ants happy? Why the science on invertebrate feelings is evolving

Does a worm feel pain if it gets trodden on? Does a fly ache when its wings are pulled off? Is an ant happy when it finds a food source? If so, they may be sentient beings, which means they can "feel", a bit or a lot, like we do. Invertebrate sentience is becoming an ever livelier topic of debate and with new science we are getting new insights. But Dr Andrew Crump at the Royal Veterinary College, who helped ensure that new UK laws recognising animal sentience were amended to include large cephalopod molluscs and decapod crustaceans - octopuses,…