Should the undoubted intelligence of octopuses change the way we treat them? This question has been asked a lot of late because of the documentary My Octopus Teacher. The film is about a year-long relationship between a man and an octopus, and it takes place in a kelp bed off South Africa. It celebrates the sensitivity, awareness and intelligence of the octopus. That’s a difficult concept. Octopuses — octopi is wrong because it’s not Latin and octopodes is insufferably pedantic — are molluscs. That’s the same phylum as slugs and snails and cockles and mussels. In other words, intelligence is not restricted to our own phylum of chordates or back-boned animals. As flight independently evolved in birds, bats, insects and the extinct pterosaurs, so intelligence has evolved independently in at least two phyla.