Rare images of dolphins help scientists crack the mystery of marine mammal communication

connectVideoWATCH: Dolphins greeted paddle border with a friendly bump

An observer was waiting for the movie surfers when he noticed a school of dolphins trying to chase fish off the coast of Gracetown, Australia. When the holder of twenty or so dolphins turned to catch a wave, a dolphin jumped up and hit a stand up paddle boarder right out of his board of directors with a friendly bump!

Brazil Araguaian river dolphin may not be as big of a loner as researchers previously thought.

The river dolphin species generally referred to as “botos,” were first discovered in 2014. Since then, scientists have been eager to learn more about the mysterious creatures. Just 600 to 1500 are estimated to be in existence in the South American country, the Araguaia-Tocantins River system, per a 2014 study published in the Journal PLOS One.

In contrast to their saltwater brothers and sisters, Araguaian river dolphins were regarded as a shy, solitary animals with “little social structure that would require communication at the University of Vermont, explained in a press release on Thursday.


But a recent expedition to the Brazilian city of Mocajuba changed researchers ‘ conclusions about the species and potential “cracked the code” of how communication has evolved in marine mammals.

Biologists Laura May Collado and Gabriel Melo-Santos of the University of Vermont and the University of St. Andrews in Scotland, respectively, brought a team equipped with underwater cameras and microphones in the Brazilian city of Mocajuba, where botos have been more present. After analysing 20 hours of recordings of the species, the researchers were able to identify 237 types of sounds.

The team’s findings were published in the journal Peer J on Thursday.

Brazil Araguaian river dolphin can be up to 237 different sounds.
(Mark Carwardine/Barcroft Media/Getty Images)

“We find that they deal with each other, and make more noise than previously thought,” Collado said in an online statement. In fact, “their vocal repertoire is very diverse,” she added.


“The majority of the studies with Amazon River dolphins, as well as other river dolphins around the world, reported few sounds used for communication,” Melo-Santos added to Gizmodo. “Some studies would even state that botos had a simple communications system composed by low noise types.”

River dolphins actually use the same signature to call, and sounds like their marine counterparts, but they represent different needs.

“It’s exciting; marine dolphins, including the bottlenose dolphin signature whistles for contact, and here we have another sound used by the river dolphins for the same purpose,” said Collado, adding they may even have the opposite purpose — as a signal to keep your distance.

They also have a lower tone than the other dolphins, which researchers believe may have changed, together with their surroundings, which is allegedly threatened by the oil and gas, mining, fisheries, pollution, among other issues.

“There are a lot of obstacles, such as flooded forests and vegetation in their environment, so this signal may have evolved to avoid that the echoes of the vegetation and the improvement of the communication range of mothers and their calves,” Collado added.


Since river dolphins, in general, were documented long before other dolphins, the group of the findings may point to their “language” may have contributed to the calls and the call you hear from marine dolphins today.

In the near future, the researchers hope to delve into the other river dolphin species to see how their communication and to compare it with the botos.

“We can’t say what the evolutionary story is still up and we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we find,” she says. “We now have all these new questions to explore.”

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