Do dolphins heal their own wounds?
Scientists think that dolphins rub against coral to treat wounds on their skin. The New Scientist magazine in May 2022 explained that Bottlenose Dolphins appear to look for specific corals and sea sponges that produce anti-bacterial or hormone-like substances, which may indicate that they are trying to heal their own wounds and infections by rubbing against them.
Scientists have observed orcas and Beluga whales rubbing their bodies against underwater sand and pebbles, but similar behaviour in dolpins has not been widely observed.
Research scientists at the University of Zurich in Switzerland wanted to study dolphin behaviour. They filmed Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the wild in the Red Sea off the coast of Egypt. While they were filming, they saw a pod of dolphins lining up to rub themselves against specific corals and sea sponges.
They noticed the dolphins repeatedly rubbing themselves on corals that released mucus. The scientists thought the dolphins might be self-medicating.
Researcher Angela Ziltener said, ‘They always come back to the same organism and they are really rubbing different body parts on them. The behaviour is not observed in sand or in seagrass, for example. It’s a different behaviour. They’re queueing up and waiting their turn.’
The researchers took samples of the corals that the dolphins were rubbing against. They included a Gorgonian Coral (Rumphella aggregata), a Leather Coral (Sarcophyton sp.), and a Sea Sponge (Ircinia sp.). They analysed the samples using a high-resolution spectrometre in the laboratory to identify the chemicals and properties in the coral mucus.
In the sampled corals, scientists found 17 bioactive compounds with anti-bacterial, anti-oxidant, or hormone-like properties.
Angela Ziltener and her team cannot be certain that the dolphins are using the coral’s mucus and sea sponge’s substances for medicinal purposes, or to keep their skin healthy by treating bacterial infections. More research is needed.
Jason Bruck at Stephen F. Austin State University in Texas, who was not involved in the Bottlenose Dolphin research, agrees that more research is needed.
Bruck says that dolphins replace their outermost skin layer every two hours or less, which is nine times faster than humans replace their outermost skin. So, are the dolphins using the corals to rub off their outermost skin or are they seeking specific corals with healing properties to heal their skin. Bruck thinks that the dolphins’ ‘unique dermal anatomy and physiology’ means that people shouldn’t assume that the medicinal effects of corals would be the same for dolphins and humans, but further research could help us to understand the importance of coral and its relationship with ocean mammals.
Journal reference: iScience, DOI: 10.1016/j.isci.2022.104271
Photographer: Martina Nicolls
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