when members of the rough-toothed species (Steno bredanensis) travel in tight formations, only one emits sounds to scan for prey and distant objects, while the others stay silent, listening in on the echoes that bounce back. The authors say this behavior may help the dolphins save energy as they trek.
The tag line of their write-up is "Stealing Sonar". The word 'stealing' doesn't seem appropriate in this context, but I guess it is attention getting. I tried to track down the article (without success) to see if the authors proposed other explanations for the behavior. It seems to me that the dolphins could also be trying to minimize the chances of alerting prey OR confusing themselves with multiple reflections (sort of a sonar version of the cocktail party effect where too many people talking at once makes listening difficult). However, this is not my area of expertise, so I may be completely off base.