Dolphins may rub on specific corals andsponges to treat their skin, researchers reported Thursday in the journaliScience. These stationary sea creatures may serve as drive-by pharmacies,dispensing a chemical cocktail that could treat bacterial or fungal infectionsor support skin health. The scientists said cetaceans have not been observedself-medicating before.
Angela Ziltener, a biologist who works at theDolphin Watch Alliance in Switzerland, spotted this behavior in 2009. Dolphinslined up in front of a coral and each one took their turn, sometimes circlingto the back of the line for another go.
The dolphins seemed to have clear preferences— out of hundreds of coral species in the reef, they used a select few,Ziltener said. Sometimes after the dolphins hit up a coral, their skin wasstained yellow or green. Knowing that sponges and corals contain an assortmentof chemical compounds, Ziltener connected with Gertrud Morlock, an analyticalchemist, to investigate whether the dolphins’ behavior could be explained bywhat’s in the goo these creatures exude.
In 2019, the researchers snipped tiny piecesfrom two soft coral and one sponge species they had seen dolphins rubbingagainst in the Red Sea. Combining several powerful techniques, the teamsleuthed for substances. Morlock said they found 17 bioactive compounds.
Some of these molecules may serve as immuneboosters or sunscreens, said Julia Kubanek, a marine chemist.
She noted that the scientists didn’t reportwhether dolphins prefer to rub against corals and sponges that contain morebioactive compounds.
Self-medication “seems totally plausible,”said Eric Angel Ramos, a marine mammal scientist. “But equally it’s plausiblethat they just love to rub against it.”
He suggested testing whether the dolphins geta medicinal benefit from these invertebrates by working with captive animals.They often scratch, bite or otherwise beat up one another, which provides anopportunity to track how dolphins’ skin fares after some coral or sponge skincare.
The research team is working to analyzefootage of thousands of dolphin rubs on corals and sponges, Ziltener said. Thatdata could contain clues to whether the dolphins are getting an Rx on the reef.If some of them repeatedly dose themselves, that could bolster the case forself-medicating.
