Smart dolphins use sponges as 'accessories' to make hunting easier

London, Jan 4 (ANI): A new study by researchers at Georgetown University in Washington DC has revealed that dolphins have developed tools to help them hunt for food.

According to the researchers, the discovery suggests that mammals could be even smarter than previously thought.

Bottlenose dolphins from an extended family in Australia's Shark Bay have taken to protecting their noses with pieces of sponge when foraging for fish on the abrasive seabed.

According to the researchers, a single dolphin discovered the foraging technique by chance and then passed it on to her offspring.

Its use has had a marked impact on the dolphins' hunting and social behaviour as the animals deploying the sponge tool spend more time alone, rummaging through sand.

The researchers said that discovering a new tool is a direct sign of intelligence.

"There's a strong link between animals with larger brains and tool users. Bottlenose dolphins have a brain second in size only to humans," Times Online quoted Janet Mann, a marine biologist who led the research, as saying.

"Dolphins are already good at catching fish so they don't need tools, but they've discovered this sponge makes their job easier. Working out how to use tools in a creative way like that is a hallmark of intelligence," Mann added.

The foraging technique came to light a few decades ago when a local fisherman spotted what looked like a strange tumour on a dolphin's nose.

Eventually, researchers worked out that the 'tumour' was a conically shaped sponge and it became apparent that the dolphins would spend considerable time searching for one the right shape to fit their nose.

The sponge is used to scatter the sand gently on the sea floor and disturb buried fish. When a fish is spotted, the dolphin drops the sponge and gives chase.

During the study, the researchers also discovered that although dolphins tried to teach the hunting technique to all their young, it was mainly female offspring that grasped the concept. (ANI)