They were selective about the type of corals they rubbed, noted wildlife biologist Angela Zeltner, a guest researcher at the University of Zurich who spent the next 13 years trying to unravel the bewildering behavior.
The results of her comprehensive research on the 360 Dolphin community were published Thursday.
By observing dolphins and studying the properties of corals, Zeltner and her colleagues have discovered that dolphins seem to use the reef as a medicine box: the bioactive compounds in the mucus released by two different species of corals and sea sponges. Possibly helping dolphins protect their skin.
It took Ziltener years of diving with the local dolphin population to gain their trust. “You kind of have to adopt the dolphins,” she said. “It took me time to see all their secrets.”
Dolphins have rubbed only the gorgonian corals known as Rumphella aggregata, and the leathery corals Sarcophyton sp. , and the sea sponge Ircinia sp. Ziltener noted. Moreover, they used living organisms in different ways.
With leathery coral and sponge – They are more compact and firmer in texture than soft Georgian coral branches – the study found that dolphins tend to push an isolated part of their body inward and wrap it around. In contrast, they inserted their entire body into the Gorgonian reef multiple times, rubbing multiple parts of the body simultaneously.
The dolphin’s rubbing behavior on gorgoning reefs, called gorgoning, was first revealed by Ziltener’s research in 2017 in the BBC’s “Blue Planet II” and a number of other nature documentaries. However, this is the first time that a detailed study of the behavior has been published in a scientific journal.
When in groups, the dolphins often line up and take turns rubbing against the gorgonian corals. interacts with Coral skinning did not appear to have been a group activity.
With leathery coral, the dolphin would sometimes pick it up from the ground and hold it in its mouth for a few minutes, swinging it around—an action that caused compounds to seep out of the coral and spread around the dolphin’s head, staining it yellow-green.
Because the reefs are protected, the team got permission to take small samples – just a centimeter – From coral reefs and sea sponge used by dolphins. Analysis of the study found that these organisms contain 17 biocomplexes, which have different properties, such as antibacterial, antioxidant or hormonal properties, said co-author Gertrude Morlock, analytical chemist and University Professor Food Science at Justus Liebig-Giesen University in Germany.
The three different living things It showed similar and some different effects, Morlock said.
“The common factor was that all three had a wealth of antibacterial and antimicrobial activities. What was particular to the leather shed, for example, contained estrogen-like compounds while the other two were not.”
“We were surprised that there were so many (complexes),” she said. “We think[dolphins]clearly choose these substrates, and we’ve demonstrated that they contain bioactive compounds and when you come into contact with this[coral], Their skin is in direct contact with these molecules. “
Morlock explained that the purpose of the behavior is likely to regulate and protect the skin microbiome — a bit like the way humans use skin cream. She said the research team had no conclusive evidence that dolphins were using coral as a form of medicine, although dolphins regularly suffer from fungal infections and rashes.
Not every dolphin in the capsule rubbed coral. Only young calves under a year old watch them, Zeltner said. This led the researchers To believe that behavior is learned, not innate.
“This ability to remember behaviors and their implications, and then repeat those behaviors to treat future skin problems adds (to) a wealth of evidence that dolphins are intelligent,” she said.
Dolphins have long been seen as highly intelligent animals capable of communicating and using tools, such as shells, to help them hunt. It’s possible for other marine animals to use coral in this way, Zeltner said, but it’s difficult to systematically monitor underwater animals.
Zeltner said dolphins often wake up from naps to perform the coral-rubbing behavior.
“It’s as if they are taking a shower and cleaning themselves before they go to sleep or wake up in the day,” she said.
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