- Male bottlenose dolphins synchronise their calls and movements when working together.
- Researchers believe this helps them to strengthen bonds and co-operate well.
- Co-operation could help to reduce stress in dolphins, like it does in humans.
Male bottlenose dolphins match the tempo of each other’s calls when working together, as well as synchronising their movements, a study has found.
An international team of researchers used long-term acoustic data from the famous population of dolphins in Shark Bay, Western Australia. The study, published in the journal Proceedings of the Royal Society B, found that male dolphins co-ordinate their behaviour in a similar way to humans when working together.
Male dolphins were shown to match the tempo of their partner’s calls and sometimes produce their calls in sync. It was previously thought that only humans used both physical and verbal synchronised actions to strengthen bonds and improve co-operation.
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The research was carried out by an international team from the Universities of Western Australia (UWA) and Bristol.
Dr Stephanie King, senior lecturer from Bristol’s School of Biological Sciences, said: “Male dolphins need to work together to herd a female and defend her from rival alliances, but they are also competing to fertilise her.
“Such synchronous and co-ordinated behaviour between allied males may therefore promote co-operative behaviour and regulate stress, as it has been shown to do in humans.”
In humans, synchronised actions can lead to increased feelings of bonding, foster co-operation and reduce the perceived threat of rivals. Apart from humans, very few animals co-ordinate both vocal signs and physical movement when working together.
The study found that male bottlenose dolphins not only synchronise their movements but also their vocal behaviour when working in alliances.
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Bronte Moore, who worked at UWA’s School of Biological Sciences, said male bottlenose dolphins “can form alliances that can last for decades”.
“To advertise their alliance relationships and maintain their social bonds, they rely on synchronous movements,” she said.
The study was funded by The Branco Weiss Fellowship – Society in Science, and the National Geographic Society.
Reader Q&A: Can marine animals get the bends?
Asked by: Eleanor Caldwell, London
In scuba divers, the bends is caused by ascending too quickly. Nitrogen dissolved in the bloodstream can form bubbles before the gas has had time to return to the lungs, causing pain and tissue damage. Marine animals, however, don’t normally suffer from this condition.
To find out why, scientists recently put a dead dolphin and seal in a pressurised chamber and carried out a CT scan. They found that the marine mammals’ lungs were separated into two regions: one filled with air, one collapsed. As the lung is collapsed, so too are the little air sacs inside the lung, where gas exchange takes place.
It’s thought that the blood flows mostly through the collapsed part of the lung, minimising the amount of nitrogen that can enter the animal’s bloodstream, while still allowing some oxygen and carbon dioxide to pass.