How do you avoid jellyfish? Look at the sea: if they are there, they are usually seen and the only way to avoid them is … don't swim. Jellyfish do not attack us, they do not come towards us: we are the ones who go at them. As Ferdinando Boero, marine biologist of the University of Salento, explains: «Jellyfish move vertically, so they can stay on the surface and can go down to the bottom. They are animals that move, and often go where the currents carry them. There are no predefined rules: you find them everywhere. Because jellyfish are part of plankton and move with the current. They can swim but cannot counteract the movement of the currents ».

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If I see a distant jellyfish, can I dive in? If there are stinging jellyfish in the sea it is better not to bathe, unless there are very few. Jellyfish that sting usually have very long tentacles: Pelagia reaches 10 meters while Physalia (also called Portuguese Caravella) reaches even 20 meters. So even if the jellyfish seems far away, its tentacles are not necessarily close.
Can jellyfish kill? Yes, some jellyfish can cause anaphylactic shock. Furthermore, the severe pain that causes the puncture can be fatal in individuals with heart problems. It is therefore necessary to go to the emergency room in case of diffuse skin reaction, difficulty breathing, sweating, pallor and disorientation.
Tells Boero: «In Australia, jellyfish are more victims than sharks. And Physalia - in Florida - killed. But to date there have been no cases of victims due to jellyfish stings in the Mediterranean, even though often the peaks end up in the hospital ».

Can non-stinging jellyfish be touched? Better not, even if their poison is almost harmless to us. Even the tentacles of harmless jellyfish, in fact, have cnidocysts (the small cellular organelles that contain the poison) that can remain on the palm of the hand and, if we don't wash them and then touch our eyes (or other delicate parts), we can transfer the poison and cause inflammation.

What is the stinging jellyfish liquid made of? From a mixture of three proteins: one with a paralyzing effect, one with an inflammatory effect and a neurotoxic one. "There are no specific antidotes for these poisons - explains Boero - which, however, are thermolabile, ie they degrade at high temperatures".
What do you feel when you're points? A local inflammatory reaction that causes burning and pain. "The skin reddens and small bumps appear like pomfi, but after about 20 minutes the burning sensation is exhausted and the sensation of itching remains, " explains Francesco Sacrini, a specialist in dermatology at the Humanitas Clinical Institute in Milan. The degree of pain-burning varies according to the areas affected and becomes unbearable if more than 50% of the body surface is affected.
What to do when you're points? Stay calm, breathe normally, get out of the water immediately and then wash the affected area with sea water. "Staying in the water is dangerous because you can also have serious reactions such as anaphylactic shock, " advises Mario Aricò, a dermatologist at the University of Palermo and head of the dermatology division at the Giaccone hospital in Palermo.
Sacrini states: «The first thing to do is to wash with sea water and not with fresh water because this would favor the discharge of the venom of the cnidocysts. Sea water, on the other hand, is essential to clean the skin of parts of jellyfish that have remained attached to the skin and to dilute the toxin not yet penetrated ».
Grandma's remedies: do they work? Do-it-yourself remedies such as applying a warm stone (or water) to the part, rubbing with hot sand, washing with ammonia (or urine), vinegar or alcohol, are not only useless, but can also worsen the situation. The heat of a stone or sand is absolutely useless because to eliminate toxins it would be necessary to reach 40-50 degrees. Not even the ammonia and urine that contains it serve: they are not deactivating the jellyfish toxin and could further ignite the affected part.
What is the medication to do? To have an immediate antipruritic action and to stop the spread of toxins it is good not to scratch and apply an astringent gel to aluminum chloride. "They are not products easy to find on the market - advises Arricò - but can be prepared by the pharmacist indicating a concentration ranging from 3 to 5%". The ideal is a 5% concentration.

Soothing seawater-based sprays and natural astringent substances work equally well. "Cortisone creams or antihistamine-containing creams, on the other hand, are useless because they come into action only 30 minutes after application, that is when the maximum reaction is exhausted naturally" explains Sacrini.

Image A sea jellyfish (Rhizostoma octopus). | Hans Leijnse / NiS / Minden Pictures / contrast

Finally, how can we avoid the scar on the skin? We must not expose the part to the sun, but keep it covered until the inflammation that can last even two weeks is over. The area of ​​skin affected by jellyfish, in fact, tends to darken because it remains sensitive to sunlight.
Goggles, mask and jellyfish suits help? Swimming with goggles or a mask helps you look underwater and see any dangers and a surf suit can protect your skin. Also useful are the new anti-medusa coveralls designed and produced in Australia, for sale in Italy online .
And the anti-jelly creams? In medical literature the creams called "antimedusa" have been formulated by studying the protection mechanisms used by clown fish [fish that has a repellent substance for jellyfish, ed]. Antimedusa creams, currently on the market, are associated with sunscreens. They are based, as described in scientific works, mainly on 4 principles:

  • they make the skin slippery and consequently difficult to cling to the tentacles of jellyfish;
  • they confuse the mechanism of recognition of the jellyfish;
  • block the activation system of the stinging cells e
  • they fight the osmotic pressure that forms inside the nematocysts [which are the urticating organs of the jellyfish, ed].
  • It is possible to have a variable response depending on the jellyfish species, the correct application and the time spent in the water.

    The advice of not diving when the jellyfish are present in the sea is still valid.

    Finally, is it true that jellyfish love clean and warm seas? Their presence does not necessarily mean that the water is clean even if, like all animals, jellyfish do not like pollution. Boero says: "There are species that prefer cold waters (including arctic ones), and species that prefer warm ones. Just like fish: there are the tropical ones, the arctic ones, the coastal ones, the deep ones ».
    Is there a season when jellyfish populate the seas the most? Usually, jellyfish become more abundant after spring. Boero says: «First there is the flowering of phytoplankton (around February - March), then that of crustaceans, around March April, and then jellyfish begin. Velella (which is not a jellyfish) is very abundant towards April May (also this year), while Pelagia is more summery. But this year it has started to be present since February ».