Scientists from Aberdeen University studied a colony of more than 100 bottlenose dolphins in Scotlands Moray Firth. The animals communicate by whistles and, to a degree, by clicks (whose prime role is location by echo response).

The teams findings led them to believe that, once groups disperse into smaller schools to hunt for food, effective communication skills allow them to signal over wide distances on where to find food or, say, to warn of danger. The dolphins therefore co-operate to help each other survive.

The scientists also established that the dolphins, just like humans, surround themselves with a number of general friends and have a smaller number of especially close companions.

Sub-groups that go off to hunt together tend to be close-knit, but there is a degree of visiting by dolphins from one school to another, making for even more effective information transfer.