Dolphins Seen Self-Medicating Skin Ailments by Rubbing Against Certain Corals and Sponges


Rashes are irritating for humans, as well as other animals, especially when they itch. When a dolphin gets a rash, they can’t just run down to the pharmacy and pick up some ointment for it, but they may have a treatment method. Scientists have observed Indo-Pacific bottlenose dolphins in the Northern Red Sea getting in line to rub themselves against corals, purportedly to treat skin conditions, reported

The first time wildlife biologist at the University of Zürich, Switzerland, and co-lead author of the study Angela Ziltener saw dolphins rubbing themselves against coral off the Egyptian Coast in the Northern Red Sea was in 2009. After observing that the dolphins chose certain corals to rub against, she and her research team wanted to understand the meaning behind the behavior. 

In a new paper, Ziltener and her team demonstrated that the corals the dolphins chose to rub against have medicinal properties, which led the scientists to believe that the dolphins are using them to self-medicate skin conditions.

“I hadn’t seen this coral rubbing behavior described before, and it was clear that the dolphins knew exactly which coral they wanted to use,” said Ziltener, as reported. “I thought, ‘There must be a reason.’”

The study, “Evidence that Indo-Pacific bottlenose dolphins self-medicate with invertebrates in coral reefs,” was published in the journal iScience.

According to the study, Ziltener and her team have been studying about 360 Indo-Pacific bottlenose dolphins in the Northern Red Sea around El Gouna and Hurghada and have observed dolphins rubbing their skin against specific marine species: gorgonian coral (Rumphella aggregata), leather coral (Sarcophyton) and the sponge species Ircinia.

“It’s very intensive,” Ziltener said of how dolphins act with certain corals, as reported by The Guardian. “They don’t just go through [the coral] – they go up, they come back down again and they rub their belly, their ventral area and the back.”

Ziltener dived down to observe the dolphins, and it took a while to get them to trust her, reported. Once she and her team were able to get close to the dolphins on a regular basis, they observed that when the dolphins rubbed against the small polyps of the corals, mucus was released. 

The team gathered coral samples, and, upon analysis by lead author and analytical chemist at Justus Liebig University Giessen in Germany Gertrud Morlock and her team, it was discovered that the gorgonian coral, leather coral and sponge species contained “17 active metabolites with antibacterial, antioxidative, hormonal, and toxic activities,” reported

The presence of the substances led the researchers to conclude that the mucus was being used to medicate the dolphins’ skin.

“Repeated rubbing allows the active metabolites to come into contact with the skin of the dolphins,” Morlock said, as reported. “These metabolites could help them achieve skin homeostasis and be useful for prophylaxis or auxiliary treatment against microbial infections.”

The reefs containing these medicinal corals are recreational places where dolphins congregate to take naps and refresh themselves, like something akin to dolphin spas.

“Many people don’t realize that these coral reefs are bedrooms for the dolphins, and playgrounds as well,” Ziltener said, as reported by “It’s almost like they are showering, cleaning themselves before they go to sleep or get up for the day.”

Out of concern for the dolphins and their habitat, Ziltener started the conservation group Dolphin Watch Alliance to educate tourists, tour guides and the public on how to conduct themselves in a way that won’t harm the dolphins.

“The tourism industry makes a lot of money now out of dolphin swimming. People are dreaming of swimming with the dolphins, so they are figuring out which reefs they use and disturbing the dolphins if they don’t follow the guidelines for how to approach them in a responsible way,” Ziltener said, as reported.

Ziltener and her team hope to one day pinpoint which corals and sponges the dolphins use to medicate particular parts of their bodies.

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