Dolphins are smart--but who knew they could do math? A research team from the University of Southampton has shown that the animals use something akin to advanced mathematics when they hunt.

Dolphins have long been observed using a hunting technique in which they blow bubbles around fish to force them closer together (the so-called "bubble nets" make the fish easier to catch). The dolphins then use echolocation (sonar) to pinpoint their prey. But how do dolphins distinguish the fish from the bubbles?

Research led by Dr. Tim Leighton, a professor of ultrasonics and underwater acoustics at the university, suggests that dolphins somehow "count" the feedback from the sonar signals they emit--an ability that seems to require advanced "nonlinear" math.

"These dolphins were either 'blinding' their most spectacular sensory apparatus when hunting--which would be odd, though they still have sight to reply on--or they have a sonar that can do what human sonar cannot," Dr. Leighton said in a written statement.

When they use sonar, dolphins emit clicks of varying strength (amplitude)--a phenomenon that seems to be central to their amazing ability.

"The variation in amplitude of these clicks is the key," Leighton said. "It produces changes in the echoes which can identify the target [fish] in the bubble net, where man-made sonar does not work."

Leighton found that an advanced form of sonar called biased pulse summation sonar (BiaPSS) can do what dolphins do naturally--separate sonar "clutter" from prey. The research doesn't prove that dolphins use this technique but shows it's possible.

"The researchers are asking whether or not it’s feasible," engineer Hugh Griffiths from University College London in England told ScienceNews. “And they conclude--quite rightly--that yes, in principle, it is.”

The research was published in the journal Proceedings of the Royal Society A on July 12, 2012.

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