A swim in the North Sea: is it safe (with all those jellyfish)?

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Jellyfish are the last thing that many beach visitors want to see, let alone feel in the water. Even so, there is no need to be too concerned and the poison from our jelly fish is little to worry about. Been stung? Then there are some things you can do to relieve the pain. Pee for example, or is that a myth?

This article was first published on July 7, 2022. The interviewee was contacted for an update in July 2023.

In the summer particularly, it is very likely that you will see jellyfish floating around close to the shore. But there’s no need to be afraid of them, says Sara Vandamme (Marine@UGent) reassuringly. “A jellyfish bite is not pleasant, but our North Sea jellyfish are much less toxic than their Australian cousins. Some people suffer an allergic reaction, similar to a bee or a wasp sting. In that case it is best to call the lifeguards immediately.” 

To pee or not to pee?

The most famous jellyfish, the common or moon jellyfish, is unable to penetrate the skin. However, you may be stung by a blue jellyfish or compass jellyfish. “The sting of a compass jellyfish can be compared with a nettle sting. Annoying, but rinse it well with sea water and the irritation soon disappears”, says jellyfish fan and professor in marine biotechnology Jana Asselman. 

Does peeing on a jellyfish bite really help to soothe the pain? Yes and no, is the answer to that one. “The poison in some jellyfish is thermolabile, which means that it breaks down more quickly when it’s hot. However, that is not the case for all jellyfish. In general, the best remedy is to rinse the wound well with sea water. Or with vinegar, but that only works with the compass jellyfish and actually causes more pain in the case of other species. Since most people don’t recognise the difference between the different types of jellyfish we strongly advise against rinsing with urine, drinking water and alcohol”, recommends marine ecologist Colin Janssen. 

What about the Lesser Weever?

So, all in all, those jellyfish are not so bad. A far more vindictive sea creature is the Lesser Weever. A jab from this fish can be very painful. So watch out, especially if you know they can found in places where children like to play. Sara: “The Lesser Weever buries itself just below the surface of the sand, and only the black spine beside its head emerges.” “They are mostly found in pools around sandbanks that are left on the beach at low tide, or ‘kellen’ as these are called in West Flemish”, says Colin.


The Lesser Weever
© Decleer, Misjel

Fortunately, peeing on the site of the bite can bring a little relief. Sara: “That’s because the poison in the Lesser Weever is broken down by heat.” That means it is just as effective to apply something else that is warm, for those that prefer to skip the urine.

Longer life at sea

In any case it would be such a shame, according to Colin, Jana and Sara, if people were put off by these ‘risks’. These are peanuts compared to all the benefits that the sea has to offer. 

Jana: “When we are at the seaside, we have more physical exercise than we do at home, that’s for sure. Exercise has a positive impact on our physical health and mental well-being. During the lockdown, people living by the sea felt less depressed than people living inland, it appeared in a study by the VLIZ (Flemish Institute for the Sea) in collaboration with a number of colleagues at Ghent University.”

And there also seems to be a positive sea effect in general: “People who live by the sea live more healthily and for longer. But we don’t yet know why. We suppose that the sea air has something to do with it.” The iodine in the air? “No, the iodine content is too low to have any effect (laughs). However, there are a thousand and one substances in the air that come from algae, seaweed, … Even jellyfish. In fact, some of the most innovative medicines are founded on jellyfish poison.” Jolly amazing those jellyfish!

Colin Janssen

Professor Colin Janssen (Faculty of Bioscience Engineering, department of Animal Science and Aquatic Ecology) kicked off his academic career as an eco-toxicologist and (applied) marine ecologist. These days, along with Jana Asselman and Sara Vandamme, he focuses on the research domain of ‘Ocean & Human Health’. “Right from my earliest childhood moments, the beach was my playground. I always took the things I found back home with me, often to my mother’s disgust (laughs).”

Jana Asselman

Jana Asselman is a professor in Marine Biotechnology, associated with the Ghent University campus at Ostend Science Park, the first Belgian science park dedicated to companies in the marine and maritime sector. Researchers, companies and government bodies collaborate intensely on the blue economy. Her research targets the interactions between the sea and human health. She is fascinated by jellyfish. “I think they are beautiful, they dance up and down so gracefully and peacefully in the sea, and come in all kinds of colours and shapes.”

Sara Vandamme

Sara Vandamme is a coordinator at Marine@UGent. She lives and works at the coast and is a trained sea swimmer. Sara has personally experienced a sting from a Lesser Weever. “Really painful, but luckily someone had some warm coffee handy, which I immediately poured over!”

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