Touching it is extremely painful and has an effect for weeks: Anyone who bathes in the Mediterranean should beware of stinging jellyfish. Many coastal regions are currently experiencing a real plague. Experts are concerned, but also emphasize the great benefit of the animals.
They can really spoil a vacation day by the sea: on the Mediterranean Sea, purple jellyfish, about the size of an apple, are increasingly tormenting bathers. Touching their tentacles is incredibly painful. Since mid-June, the fire jellyfish Pelagia noctiluca has multiplied explosively off the coasts of Corsica and the Côte d'Azur and is making bathing galling for holidaymakers on many southern French beaches. The Italian Simone Martini can sing a song about it. It caught him on a beach in Ajaccio, Corsica. "Two weeks later, the bite still hurts sometimes," he says of the wound on his forehead.
There are many tips on how to relieve the pain, but oceanographer Fabien Lombard has doubts about most of the methods: "Peing on the wound certainly doesn't help," says the expert from the marine research institute Laboratoire d'Océanographie de Villefranche/Mer, laughing . Above all, however, one should not "rinse the affected area with sea water or rub it with sand".
Squirrel jellyfish shoot tiny harpoons containing a poisonous cocktail from stinging capsules attached to their tentacles. "Jellyfish are blind, so they sting anything they come across to see if they can eat it. They inject neurotoxins to paralyze their prey and enzymes to digest them," explains Lombard.
Scientists worry about jellyfish for other reasons. In a report published in 2019, the Intergovernmental Panel on Climate Change (IPCC) warned that the proliferation of jellyfish would lead to "gelification", i.e. a kind of mucous contamination, in the seas. Fabien Lombard has doubts: "We don't have any reliable measurements that show that there are more jellyfish." However, he admits that "in the 80s and 90s in Villefranche-sur-Mer there were alternately five to six years with jellyfish and five to six years without jellyfish". But this year is "already the 25th in a row with jellyfish".
However, Lombard warns against seeing the jellyfish plague as a problem in itself. Rather, it is a symptom of the overfishing of the seas. For Lovina Fullgrabe from the Corsican marine research institute Stareso, the overfishing of tuna and sea turtles, which both eat jellyfish, is one of the most plausible hypotheses to explain the more frequent occurrence of jellyfish.
Jellyfish have been inhabiting the seas for around 600 million years. Science has some breakthroughs to thank for the cnidarians. The 2008 Nobel Prize in Chemistry, for example, was awarded for the use of the phosphor from jellyfish in the visualization of cell processes, for example in Alzheimer's research. The US space agency NASA is using jellyfish to study reproduction in weightlessness, and since 2017 the European Union has been working with the "GoJelly" project to find out how jellyfish could be used in nutrition, fertilization or against environmental pollution.
According to Lombard, jellyfish can be used as feed in fish farming or to maintain soil moisture, for example in viticulture or rice cultivation. The jellyfish's collagen is sometimes used in diapers or tampons to bind moisture, and in some places even makes concrete more flexible and thus more earthquake-resistant, says the marine researcher. Research is also being carried out into how jellyfish can help with the formation of cartilage in the human body.
And as a last resort, people could still eat jellyfish to limit their numbers. At least that's what the UN Food and Agriculture Organization (FAO) suggested back in 2013.
