Humans prefer to associate with other humans who share their subculture. That’s why there are knitting clubs and fantasy football leagues.

And it turns out that dolphins also form cliques: Researchers found that dolphins known as spongers spend most of their time with other spongers. The study is in the journal Nature Communications. [Janet Mann et al., Social networks reveal cultural behaviour in tool-using dolphins]

Spongers are a small subset of dolphins that use marine basket sponges to hunt for prey. The dolphins wear the sponges over their beaks to protect themselves from rocks and broken coral when they are searching for nutritious food on the sea floor.

Sponging is passed down from parents to their young. And because the practice is socially learned, researchers agree that spongers are culturally distinct from other dolphins.

These findings are consistent with the notion that dolphins form fission-fusion societies—where all dolphins in a community belong to the same larger group, but have specific friends whom they spend most of their time with. Of course, scientists have yet to find out which dolphin clique is the coolest.

—Amy Kraft

[The above text is a transcript of this podcast.]

[Scientific American is part of Nature Publishing Group.]