Dolphins sponge up culture, study finds

2012-07-31 20:29

Paris - Bottlenose dolphins that have learnt to use sea sponges as hunting tools form cliques with others that do the same - the first evidence of animal grouping based on mutual interest, a study said on Tuesday.

The finding may represent the first known proof of cultural behaviour in the animal kingdom, US-based researchers wrote in a paper in Nature Communications.

They studied a group of bottlenose dolphins at Australia's Shark Bay, some of whom had learnt the skill of "sponging" - slipping a sponge on their beaks as protection against sharp rocks while scouring the ocean floor for prey.

Based on 22 years of observations, the team found that the "spongers" forged closer ties with other spongers than with dolphins that had not acquired the hunting technique.

"Like humans who preferentially associate with others who share their subculture, tool-using dolphins prefer others like themselves, strongly suggesting that sponge tool-use is a cultural behaviour," wrote the researchers from Georgetown University in Washington.

Ongoing quest

Sponging is a solitary activity.

"Dolphins don't sponge together but can identify who sponges and who doesn't," study author Janet Mann said.

"Spongers spend a lot of time hunting, tend to be solitary, but clearly go out of their way when they can to meet up. You could think of them as workaholic dolphins that prefer to meet up with the other workaholics."

The study forms part of an ongoing scientific quest for proof of animal culture - loosely defined as a form of social learning that differentiates between groups.

The first spongers were discovered among Indo-Pacific bottlenose dolphins in Shark Bay in the mid-1980s, and scientists believe they may have been using this hunting technique for centuries.

Normally, when some members of an animal group develop tool-use, the rest learn it too, as with chimpanzees using sticks to fish termites out of their nests or elephants swatting flies with tree branches.

Only calves

But in the case of the Shark Bay dolphins, only the calves of sponger females become spongers themselves, and the practice remains limited to a small subset - less than 5% of the 3 000-odd population, and mainly females.

No other example of sub-culture has ever been shown outside of humans, said the study.

"This was the first study to show that a non-human animal groups on the basis of ... behaviour even though they don't engage in the behaviour together," said Mann.

"This is more similar to how we think of human culture."

Their intelligence and communication skills make dolphins popular subjects for such research.

  • phae.rayden - 2012-07-31 21:29

    Fascinating stuff.

  • cliff.slabbert - 2012-07-31 21:57

    What brilliant animals!

  • adam.hannath - 2012-07-31 23:13

    It is a widely known universal fact that dolphins are the most intelligent species on Earth. Stupid humans...

  • clay.gray.505 - 2012-08-01 08:14

    Does this count as a form of evolution?

      Ryan Michael Leigh O'Sullivan - 2012-08-03 10:16

      It's not easy to show that behavior is based on genetics and thus able to be passed onto any offspring, so technically no this is more of an adaptation than evolution however if this behavior gives the advantage to this group over another then natural selection comes into play. Should be interesting to see after a few generations!

  • Robert - 2012-08-01 10:49

    I think that it is inevitable that as we gain more insight into the behaviour of the animals we share the earth with we will discover that us humans and them have a lot more in common. The only major difference is that we make more intense use of the materials and minerals available to us by advanced thought processes and the line between being intelligent or not as we perceive it may closer than previously believed. An example being that some animals share emotional traits akin human at the lose of a sibling or family member.

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