This should put them there they belong - at the top end of the ladder with the most intelligent animals along with primates and humans. Dolphins were trained to spy by the US Navy, and records going back to Roman times tell of them saving swimmers in distress. Chimps have been taught to use computers, while a parrot in New England is learning to surf the Internet. Pigeons are thought to hitch lifts on London Tube trains in their search for food. Weedy male cuttlefish get past bigger rivals by changing their colour to look like females - and reach potential mates.
Trout learn to avoid fishing lines - after being caught once they keep well away from bait.
Octopuses can count and distinguish different colours.