Dolphins 'form queues to use coral as medicine for skin ailments'

The coral will see you now! Dolphins form orderly queues to use coral as medicine for skin ailments, study reveals

  • Some dolphins with skin conditions ‘rub against coral with medicinal properties’
  • According to study they’re selective about which coral they use to self-medicate
  • Experts were able to dive down with a pod to identify corals dolphins rubbed on
  • Mucus of the corals is ‘regulating dolphin skin’s microbiome and treat infections’ 

Some dolphins with skin ailments use an ingenious solution to self-medicate, experts have found, after observing them forming an orderly queue to rub against coral.

The animals are selective about seeking out a particular type of coral which has medicinal properties in the mucus it releases, according to the study. 

Co-lead author Angela Ziltener, a wildlife biologist at the University of Zurich in Switzerland, first observed the dolphins rubbing against coral 13 years ago in the northern Red Sea, off the coast of Egypt.

‘I hadn’t seen this coral rubbing behaviour described before, and it was clear that the dolphins knew exactly which coral they wanted to use,’ she said.

‘I thought, there must be a reason.’

Some dolphins with skin ailments use an ingenious solution to self-medicate, experts have found, after observing them forming an orderly queue to rub against coral. Pictured is a dolphin mother teaching her calf to rub against medicinal coral

Dolphins can recognise their friends by tasting their URINE 

Similar to how dogs sniff urine left by other dogs, dolphins can recognise each other by tasting their urine, a new study reveals. 

In experiments, dolphins showed signs of recognition when tasting the urine of another dolphin that they’d already met.

Dolphins do not have olfactory bulbs, so they have to identify which other dolphins have been in the area using taste, researchers say. 

It’s thought that molecules known as lipids that are present in the urine allow dolphins to identify the individual chemical signatures of their friends. 

The researchers were able to dive down with a pod of dolphins to identify and sample the corals the animals were rubbing on.

They noticed that by repeatedly doing this, Indo-Pacific bottlenose dolphins were agitating the tiny polyps that make up the coral community, and these invertebrates were releasing mucus.

When the experts analysed the samples, they discovered that gorgonian coral Rumphella aggregata, the leather coral Sarcophyton, and the sponge Ircinia produced a substance with antibacterial and antioxidative properties, among others.

This finding led the team to believe the mucus of the corals and sponges is serving to regulate the dolphin skin’s microbiome and treat infections.

Lead author Gertrud Morlock, an analytical chemist and food scientist at Justus Liebig University Giessen in Germany, said: ‘Repeated rubbing allows the active metabolites to come into contact with the skin of the dolphins.

‘These metabolites could help them achieve skin homeostasis and be useful for prophylaxis or auxiliary treatment against microbial infections.’

The reefs where these corals are found are important places for the local dolphin populations, the experts said, because they head there to rest and to have fun. 

‘Many people don’t realise that these coral reefs are bedrooms for the dolphins, and playgrounds as well,’ said Ziltener. 

In between naps, the dolphins often wake to perform the coral rubbing behaviour. 

‘It’s almost like they are showering, cleaning themselves before they go to sleep or get up for the day,’ Ziltener added. 

The researchers said their findings highlight the urgent need to protect coral reefs for dolphins and other species.

The study has been published in the journal iScience.

Coral expel tiny marine algae when sea temperatures rise which causes them to turn white

Corals have a symbiotic relationship with a tiny marine algae called ‘zooxanthellae’ that live inside and nourish them. 

When sea surface temperatures rise, corals expel the colourful algae. The loss of the algae causes them to bleach and turn white. 

This bleached states can last for up to six weeks, and while corals can recover if the temperature drops and the algae return, severely bleached corals die, and become covered by algae. 

In either case, this makes it hard to distinguish between healthy corals and dead corals from satellite images.

This bleaching recently killed up to 80 per cent of corals in some areas of the Great Barrier Reef.

Bleaching events of this nature are happening worldwide four times more frequently than they used to. 

An aerial view of Australia’s Great Barrier Reef. The corals of the Great Barrier Reef have undergone two successive bleaching events, in 2016 and earlier this year, raising experts’ concerns about the capacity for reefs to survive under global-warming

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