Dolphins make clever changes to their sonar signals as they home in on their prey, according to a study published in the British weekly journal Nature. Operating in the dark, bats, submarines and dolphins have to rely on sound rather than vision, sending out high-frequency pings or "clicks" to locate their targets.

But they all face a similar problem: as they get closer to the target, the echo comes back faster but also becomes progressively louder. This is because more energy is reflected back than before, rather than gets lost in the surrounding water or air. And if the echo gets too loud, it could become deafening.

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I would like to believe that is why dolphins usually target large groups of fish, to hieghten the chance of succeeding in lunch. I don't think they search and hunt down single prey, it would be difficult. *Dolphins are adorable!!*