A dolphin wears a sponge for protection against sharp stones. Photo: Eric M. Patterson
Reading Dolphins are not only smart, but also inventive. To get hold of prey hiding in deep grooves in the seafloor, they use a very special tool: sponges, which they tear out and put over the muzzle like a protective mask to protect themselves against the sharp edges of the ground grooves. With observations of the animals researchers now noticed that the tool-using dolphins join together in cliques. Already a year ago, researchers had reported on the intelligent trick of marine mammals. What scientists around Janet Mann at Georgetown University have now discovered is the connection between the use of sponges as a tool and the social structure of the dolphin population. Because the examined dolphins of the genus Tursiops, to which the bottlenose dolphin belongs, maintain highly complex interactions with their conspecifics: There are relationships that last a lifetime, a solid family cohesion, but also rather loose acquaintances.

Looking more closely at the relationships between 36 spongy and 69 other dolphins, the scientists concluded that mammals have a pronounced homophily - a tendency to surround themselves with similar individuals. Those dolphins who know how to prey on sponges prefer to deal with conspecifics who have acquired the same skills. These skill-based cliques are rarely found in any other mammal. From this the researchers conclude that dolphins as well as humans can learn cultural behavior.

Janet Mann (Georgetown University) et al .: Nature Communications, DOI: 10.1038 / ncomms1983 © science.de? Sabine Short

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