Dolphins sponge up culture, study finds

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.

We live in a world where facts and fiction get blurred
In times of uncertainty you need journalism you can trust. For only R75 per month, you have access to a world of in-depth analyses, investigative journalism, top opinions and a range of features. Journalism strengthens democracy. Invest in the future today.
Subscribe to News24
Lockdown For
DAYS
HRS
MINS
Voting Booth
Matric results are out! Are you happy with your child's result?
Please select an option Oops! Something went wrong, please try again later.
Results
No, the pandemic really messed up their ability to focus
34% - 731 votes
Yes, they did well given the circumstances
66% - 1440 votes
Vote
Rand - Dollar
15.36
-0.8%
Rand - Pound
20.68
-0.4%
Rand - Euro
17.26
-0.1%
Rand - Aus dollar
10.91
+0.0%
Rand - Yen
0.13
-0.1%
Gold
1,818.88
-1.6%
Silver
23.54
-1.1%
Palladium
2,332.00
+5.9%
Platinum
1,035.50
+0.6%
Brent Crude
88.20
+2.2%
Top 40
67,364
+2.2%
All Share
73,797
+2.0%
Resource 10
75,253
+3.2%
Industrial 25
91,472
+1.8%
Financial 15
14,925
+0.8%
All JSE data delayed by at least 15 minutes Iress logo
Editorial feedback and complaints

Contact the public editor with feedback for our journalists, complaints, queries or suggestions about articles on News24.

LEARN MORE