Porpoises, whales and dolphins use 'sound searchlights'

The animals hunt with clicks and buzzes - detecting the echoes from their prey.

This study showed them switching from a narrow to a wide beam of sound - "like adjusting a flashlight" - as they homed in on a fish.Researchers think that other whales and dolphins may use the same technique to trap a fish in their beam of sound in the final phase of an attack.

This could help prevent porpoises, whales and dolphins' prey from evading their capture.

By revealing these acoustic secrets in detail, researchers are hoping to develop ways to prevent porpoises, and other toothed whales, from becoming trapped in fishing nets.

The study, published in the journal eLife, was led by Danuta Wisniewska of Aarhus University.She and her colleagues worked with harbour porpoises in a semi-natural enclosure at a conservation research centre on the coast of Denmark.

See the full article on the BBC web site

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