But over 22 years of observing the Shark Bay dolphins, a pattern emerged, and "it seemed (the spongers) were going out of their way to hang out with other spongers, " Mann said.
But 28 female spongers did form strong groups, or cliques, with other spongers who weren't necessarily related to them, the researchers report in a paper published online Tuesday in the journal Nature Communications.
Mann and her colleagues compared the strength of social connections between both male and female spongers and non-spongers that lived in the same area, thereby eliminating differences in habitat that could potentially affect grouping behavior.