大象传媒

Each spring, one pod of killer whales that feed on mackerel follow the fish down to the Straits of Gibraltar, where they supplement their diet with tuna. Tuna live at great depths and are fast swimmers so they are very difficult to catch. But the whales have worked out a simple technique. Tuna fisherman in the area need to be quick - any delay in getting their catch on board allows the killer whales to grab it. They simply wait until the fisherman have done all the hard work and then use sound to alert them to when the time is right. As soon as the whales hear the fishing lines being reeled in, they pounce, taking huge bites out of the tuna and leaving the fisherman with a ruined catch. For the whales, this is like shopping at the supermarket rather than catching your own.