Dolphin assisted fishing

In Laguna, a Brazilian city in the southern state of Santa Catarina, a phenomenal collaboration has developed between a pod of bottlenose dolphins and the local fishermen. At certain times of year the dolphins drive fish towards fishermen who stand waiting in shallow waters near the beach. When a dolphin rolls over, the fishermen take this as a sign to throw out their nets. The escaping fish become a meal for the dolphins.

The dolphins were not trained for this behavior; the collaboration has been going on since at least 1847.

This clip was taken from the Human Planet episode "Oceans - Into the Blue" on the BBC.