Ecology: Dolphins clique in more ways than one

Shark Bay bottlenose dolphins that use marine sponges as hunting tools appear to prefer other ‘spongers’ like themselves reports a paper published in Nature Communications this week. This implies the spongers represent a distinct group from other dolphins in the population through a socially learned skill, suggesting the presence of cultural behaviour in this species.

Animal tool use is related to intelligence, but it is not clear whether humans are the only animals to display cultural behaviour. Janet Mann and colleagues used social network analysis to define social preferences among spongers and non-spongers in Shark Bay, Australia over a 22-year period. They found that spongers were more ‘cliquish’ and had more sponger associates and stronger bonds with each other than with non-spongers. This finding suggests that sponge tool-use is a form of cultural behaviour and, like humans, bottlenose dolphins may prefer to associate with others who share their subculture.