Dolphins don't have book clubs, but they have other ways of forging friendships, and scientists are learning more about how these intelligent marine mammals buddy up.
A study involving biologist Simon Allen at the University of Bristol in the UK followed the activities of 37 male Indo-Pacific bottlenose dolphins living in Shark Bay in Western Australia. Some of these dolphins use marine sponges as tools to forage for food, a learned behavior.
Of the 37 dolphins studied, 13 were spongers and 24 were non-spongers. Just like us humans enjoy packing together with other people who share our hobbies, the spongers seemed to bond over their mutual food-hunting technique.
"Male spongers spend more time associating with other male spongers than they do non-spongers, these bonds being based on similar foraging techniques and not relatedness or other factors," said the University of Bristol.
An earlier study focused on female spongers and found they associated with each other more than non-sponge-using females. This new research adds to those previous observations and shows a social pattern across both male and female bottlenose dolphins.
These new insights into male dolphins were unexpected. "Foraging with a sponge is a time-consuming and largely solitary activity so it was long thought incompatible with the needs of male dolphins in Shark Bay -- to invest time in forming close alliances with other males," said Allen.
The male dolphins can form bonds that last for decades, noted Manuela Bizzozzero at the University of Zurich. Alliances help male dolphins defend and mate with females. Bizzozzero is the lead author of the study published on Wednesday in Proceedings of the Royal Society B.
Dolphins may have a lot in common with people. They seem toand can . Now we have to wonder if the tool-using dolphins have a name for their club. The Underwater Sponge Appreciation Society perhaps?