Pharmacy at sea: Dolphins ‘use coral as medicine for skin ailments’ | dolphins

Oho doesn’t like a bath scrub? Dolphins definitely do: they’re known to be smart, playful, and tactile animals, and they enjoy rubbing up against rough surfaces, napping in coral beds, and soaking on sponges like guests in an underwater spa. marine.

However, dolphins may get more from their bath scrubs than from relaxation and recreation. A study published today suggests bottlenose dolphins may be able to self-medicate their skin conditions using corals, adding to growing research into their previously unexplored medicinal properties.

“It’s very intensive,” said Angela Ziltener, one of the study’s lead authors, of dolphin behavior with particular corals. “They don’t just cross [the coral] – they go up, they come down and they rub their stomachs, stomachs and backs.

Red Sea dolphins cleaning their skin in the seagrass. The researchers found that the dolphins were meticulous in choosing which parts of their body to rub. Photography: Natalia Pryanishnikova/Alamy

Dolphins have thick, smooth and tough skin, but can be prone to skin conditions such as yeast and bacterial infections, scars or tattoo-like lesions caused by viral pox infections. These ills seem to be exacerbated by global warming.

Ziltener, a wildlife biologist at the University of Zurich, Switzerland, and his team studied a community of 360 Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the northern Red Sea since 2009. They observed that dolphins often lined up nose-to-tail to brush against corals as soon as they woke up and just before they fell asleep, as if taking a shower from the daytime. In addition to mechanical friction, the dolphins also caused the corals to release a polyp mucus.

The team also noticed that the dolphins returned to the same species of coral and seemed to be picky about which parts of their bodies to rub. They carried out laboratory tests on 48 samples of corals, sponges and coral mucus “chosen” by dolphins, including gorgonian coral Rumphella aggregateatacoral leather Sarcophyton sp. and the sponge Ircinia sp.

A dolphin swims along the seabed, its belly touching the coral
A bottlenose dolphin scratches on thick black coral (Antipathes of Rumphella) in the Red Sea. Photography: imageBroker/Alamy

The findings, published in the journal iScience, revealed at least 17 different bioactive metabolites with antibacterial, antioxidant and estrogen-like hormonal properties, all of which may be useful in skin treatments.

The compounds are not commonly used in antibiotics for humans or animals, but a growing body of research shows that certain corals and sponges have medicinal properties, including antimicrobials.

“These metabolites are useful if you have an infection,” said Gertrud Morlock, analytical chemist at Justus Liebig University in Giessen, Germany and lead author of the study. “If the dolphins have a skin infection, these compounds could have something like a healing property.

“If you think about it, they have no other options. If they have a skin problem, what can they do?

Clockwise: Examples of sponges, leather and tufted coral.
Researchers tested 48 corals, sponges and coral mucus used by dolphins, including (top left) the sponge Ircinia sp., coral leather Sarcophyton sp.and the gorgonian whip coral Rumphella aggregateata. Photography: Aliyah

The authors note that further research is needed to show what medicinal properties of coral dolphins need to treat certain diseases, and whether these properties have a measurable and positive impact on cetacean health.

Knowing more about the dolphin’s social network and demographics might help with that. According to Sarah Powell, a former marine biologist who studies how dolphins transmit their skin diseases, tracking individual dolphins who display the behavior and seeing if they have fewer skin diseases or reduced mortality compared to the rest of the group would reinforce this. argument. but did not participate in the study.

Previous research has shown that dolphins like to use coral sponges as foraging tools. “I don’t find it to be such a range that dolphins use corals and other plants in their environment for other purposes,” Powell said.

Stephanie Venn-Watson, a marine biologist who studies dolphin health and longevity and also was not involved in the research, said: “Since dolphins are by nature playful, tactile animals that like to rub, it is difficult to be sure that the dolphins are using the corals for medicinal purposes.

A next step to prove the link would be to show that corals skipped by dolphins don’t have the same medicinal properties, she said. “It’s a nice scientific itch to scratch.”