For more than 173 years humans and dolphins have worked together to catch fish on the coast of Laguna, Brazil. Dolphins initiated the cooperation some time before 1847 and taught humans what to do.
The dolphins hunt by herding shoals of mullet in the estuary. The fish would escape into shallow water except that the humans are helping.
Fishermen stand in the water with cast-nets and wait for a dolphin to signal them. When the signal comes, the fishermen throw their nets and catch many fish. The rest of the fish flee to deeper water where the dolphins are waiting to eat them.
Humans and dolphins both catch more fish than they would working alone.
Watch how it’s done in this Animal Planet video.
(photo from Wikimedia Commons; click on the caption to see the original)