[Animals] Sperm whale ‘clans’ in the Pacific mark out their culture with songs

[-Sn!PeR-]

 

Seven ancient “clans” of sperm whales live in the vast Pacific Ocean, proclaiming their cultural identity by distinctive patterns of clicks within their songs, according to a new study.

 

It’s the first time cultural markers have been observed among whales, and they mimic markers of cultural identity among human groups, like distinctive dialects or tattoos.

The discovery is also a step toward a scientific understanding of what whales say to one another in their underwater songs — something that’s still a mystery despite years of research.

 

Bioacoustician Taylor Hersh, a postdoctoral researcher at the Max Planck Institute of Psycholinguistics in Nijmegen in the Netherlands and lead author of the study published this month in the Proceedings of the National Academy of Sciences, said that sperm whales often exchange streams of loud clicks with each other when they’re resting near the surface between dives into deeper waters — sometimes more than a mile down — for prey like squid and fish.

 

The streams of clicks are divided into what are called “codas” and the calls are known as sperm whale “songs” — although they’re not very musical and can sound a bit like hammering and squeaking (Navy sonar operators used to call sperm whales “carpenter fish” for this reason). 

 

No one knows what all the sperm whale codas mean, but they can have distinctive rhythms and tempos, known as “dialects,” Hersh said. And the new study shows they include specific patterns — bursts of clicks that last only a few seconds, like fragments of Morse code — that the whales use as “identity codas” to proclaim their membership of a particular clan.

 

“Identity codas are really unique to the different cultural groups of whales,” she said.  

 

The study also shows that sperm whales emphasize their dialects when rival clans are nearby — a tell-tale behavior also seen among humans — with the result that whales from different clans usually don’t interact with one another when they occupy the same waters, she said.

 

The study analyzed more than 40 years of recordings of underwater sperm whale calls made at 23 locations across the Pacific Ocean, from Canada to New Zealand to Japan to South America. From these, the researchers extracted more than 23,000 click patterns, and then used an artificial intelligence system to determine which of them were distinctive identity codas.

 

They’ve now determined that there are at least seven distinct sperm whale “vocal clans” across the Pacific Ocean, each with their own identity codas, Hersh said. 

Each clan could consist of thousands of individual sperm whales, and calls by members of the same clan have been recorded at the extremes of the Pacific Ocean, sometimes more than 9,000 miles apart. It’s not known how many sperm whales exist in the world’s oceans, but it’s estimated there might be as few as 360,000; roughly half of them could live in the Pacific.

 

Source.