Physalia in the Atlantic: several beaches in the Basque Country and Landes closed because of this highly venomous invertebrate animal

Basques and Landes residents are finding themselves at each other's throats. Despite the holiday season being in full swing at the time of the famous summer cross-country skiing, lifeguards are starting to get into the habit of raising the red flag. This Wednesday, July 30, the swimming ban applies to the Basque beaches of Bidart and Anglet and Seignosse and Vielle-Saint-Girons in the Landes region.

The cause is the massive presence of an invertebrate: the physalia. Nicknamed the "Portuguese galley" or "sea bladder," it is very often confused with the jellyfish. Wrongly so. The physalia is much more dangerous. Libération takes stock.

A bright blue color, purple reflections, a slimy and translucent appearance that gives the impression of facing a plastic bag abandoned in the sea. In reality, a float of 15 to 20 cm supports the animal on the surface of the water, allowing it to move thanks to the sea currents and the wind.

The physalia carries a myriad of filaments and tentacles behind it, sweeping across an area 50 meters long in the most extreme cases. Enough to disrupt entire swathes of the Basque Country and the Landes region.

Already last week, some were spotted offshore, then in the bathing area. Five beaches scattered between Bidart and Anglet were forced to close. On Thursday, July 17, in Biarritz , access to the Port Vieux beach was closed due to the presence of ostreopsis algae, another problematic marine specimen, causing flu-like symptoms.

Located beneath the physalia's float, hundreds of tiny filaments spread out through the water like a drag net. The animal's long limbs allow it to hunt its prey, thus immobilizing an entire school of small fish. Its venom also serves as a defense against predators such as turtles and other octopuses.

Very unfortunate is the bather who crosses paths with a physalia. Each tentacle of the animal is equipped with a multitude of outgrowths resembling swollen pearls, which, upon contact, cause a very painful and stinging sting, enough to make the nettle sympathetic.

Its venomous filaments often detach themselves in the water and drift with the waves and currents. This can surprise the swimmer who finds himself caught in the shock, caught in a tentacle or filament like a sea bream in a trawl.

On the skin, contact causes painful lesions, similar to a burn or hives. Other, more serious symptoms can occur, such as discomfort, a feeling of loss of consciousness, or even an accelerated heart rate. On July 10, the Pays de la Loire Regional Health Agency issued a reminder that if these symptoms are present, swimmers should call the emergency services immediately.

Even dead, the physalia is a pest: the animal's tentacles and tiny filaments remain venomous for several weeks.

Emergency services recommend not rubbing the skin directly with your hand. The tentacles should be removed by rinsing the affected area with seawater and applying dry sand. Then, using a piece of stiff cardboard or a bank card, the filament should be detached. "Do not hesitate to ask lifeguards for help to take the appropriate measures ," the Landes prefect said in a press release.

In a message posted on Facebook at the end of last week, the Basque Country Community announced that its agents were remaining attentive to the development of the situation and that it was maintaining its surveillance system.

The physalia typically dives into the tropical and subtropical waters of the Indian and Atlantic Oceans. Fond of warm currents, they live there in large numbers and can gather to form impressive schools of several million individuals.

For several years, it has been observed on the coasts of Aquitaine and Charente-Maritime. It remains exceptional on the Breton coasts but was nevertheless spotted in Finistère in January 2023.