In Laguna, a coastal city in Brazil, an extraordinary partnership has developed between local fishermen and bottlenose dolphins. The fishermen would catch few fish if it were not for the help of the dolphins, who use their torpedo speed to herd large schools of mullet toward the fishermen, who stand waiting with nets in the shallows. At just the right moment, the dolphins begin a series of distinctive dives, which the fishermen interpret as a signal to throw their nets. The collaboration is win-win – the fishermen have schools of fish delivered to them on a plate, and the dolphins also find it easier to capture the fish, seemingly because the fish are disoriented by the fishermen's nets, causing them to break from their formations. The dolphins are not trained to perform this task, and it appears that for both human and dolphin the cooperative behaviour, which was documented in Laguna as early as 1847, is passed down from one generation to the next.