In the town of Laguna, on Brazil's Atlantic coast, dolphins have cooperated with local fishermen to fish for the last fifteen years or so.

 

The dolphins herd mullet towards fishermen standing in a line in the shallows, who throw out their nets to capture the fish.

 

The dolphins let the fishermen know when to throw their nets, with special head or tail slaps on the surface of the water.

 

Dolphins don't do it just to help the fishermen out; they obviously get more fish as a result too. This cooperation helps both humans and dolphins.

 

Only about 20 dolphins cooperate with the fishermen in this way, while other local dolphins do not take part. It's unclear how this arrangement between dolphins and humans started, but it appears to be a learned trait, that mothers pass down to their offspring through social learning, much as humans do.

 

Two favourites with the fishermen are called 'Scube' and 'Caroba'. Two hundred fishermen rely on Scube and friends to help them get their catch in.

 

Source: Livescience.