Animals. Jellyfish, swimming swimming but treasure of science

They are small, purple, and their stings are incredibly painful: If jellyfish disrupt bathing on the Mediterranean coast, they also have specific physiological properties, whose study has advanced science and suggests several uses.

Since mid-June, on many beaches in the Côte d’Azur and the French island of Corsica, Pelagia noctiluca, small purple jellyfish found throughout the Mediterranean, has been tossed around by dozens of sea waves. But hoping to get rid of it is illusory. Because jellyfish, which appeared 600 million years ago, are among the first inhabitants of the planet.

“When present all year round”

They consist of 95 to 98% water, brainless, able to float and swim but not withstand ocean currents, they are part of zooplankton. And “they are present all year round in a current that flows around the Mediterranean and tends to remain offshore,” Fabien Lombard, a teacher-researcher at the Villefranche-sur Oceanography Center, explained to AFP. -The sea, in the southeastern part of the city. France. “It was the southern current that brought them back to the shores.”

In Ajaccio, Corsica, thousands have been seen. On Saint-François beach, in the heart of the city, Simone Martini, an Italian swimmer, was one of the many who met their painful: covered with stinging cells, the knidocytes, the jellyfish’s tentacles brushed his forehead and loosened tiny harpoons that injecting a cocktail of poison.

A bite to eat

“Fifteen days later, I still have a burn that sometimes hurts me,” he told AFP. “These blind animals bite everything they touch to try to eat. They inject neurotoxins to immobilize their prey, and digestive enzymes,” explains Fabien Lombard.

And everyone has their own method of relieving pain after injection. “Peeing on it is useless”, laughs Fabien Lombard, who advises against “rubbing, rinsing with seawater and removing prickly cells with wet sand”.

A significant spread

At the environmental level, their spread would be such that it would cause a “gelation” of the oceans, according to a September 2019 report by the Intergovernmental Panel on Climate Change (IPCC).

A claim that divides the scientific community: “We have no reliable measurements to say that there are more,” says Fabien Lombard. While acknowledging that if “in the 80s and 90s, in Villefranche-sur-Mer, there were 5 to 6 years with jellyfish and the following 5-6 years without, this is the 25th non-stop year with jellyfish “.

For Lovina Fullgrabe, a scientist at the Underwater and Oceanographic Research Station (Stareso) in Calvi, Corsica, “overfishing, which eliminates their predators such as tuna or turtles, is one of the hypotheses” favored to explain this higher frequency. . .

And if the Food and Agriculture Organization of the United Nations (FAO) recommended eating them in 2013, in order to combat their spread, Fabien Lombard warns against the idea of ​​treating “this symptom of an imbalance in the sea” rather than the original disease, which is the depletion of Fish due to overfishing.

Two Nobel Prizes

However, if these animals are of concern, they have also enabled significant scientific progress. In 1913, the Nobel Prize in Medicine rewarded work on the function of the poison from cousins ​​to jellyfish, which made it possible to understand “anaphylactic shock”: the poison falls instead of strengthening the immunity of people who have already been stung.

“It was a bit of a revolution, until then everyone was more in the idea that + the more you expose yourself to something, the less you are sensitive to it +”, explains Fabien Lombard.

In 2008, another Nobel Prize, this time in chemistry, was awarded for working with the ability of certain jellyfish to shine in the dark via a protein. This fluorescence has been used by many biochemists, biologists and medical researchers in their research, especially on tumors or Alzheimer’s disease, the Nobel Committee pointed out in 2008.

“It has revolutionized cell biology by literally making it possible to + turn on + the cells when activated, to see how they work,” summed up Fabien Lombard.

jellyfish in space

NASA has taken jellyfish aboard spaceflights to study their reproduction in weightlessness, and the EU launched a call for projects in 2017, “GoJelly”, to investigate how to exploit them in the food sector. , fertilization, cosmetics or pollution.

Because “jellyfish are full of potential”, the teacher-researcher assures: they are used as food for aquaculture fish, fertilizers or soil moisture stabilizers for crops such as vines in Landes, rice in China or basil in Mexico. Their collagen is used in cosmetics, diapers or sanitary tampons in Israel and to soften concrete in antiseismic installations in Russia, the scientist states.

For him, the most promising use is “jellyfish slime”, composed of a molecule that “seems to promote the regrowth of human cartilage”.

To meditate during the next swim.

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