Group of jellyfish discovered living in Swiss lake

Group of jellyfish discovered living in Swiss lake

When swimming in Swiss lakes and rivers, while it’s best not to think too much about what might be lurking in the murky depths, you don’t expect the wildlife below the water line to be plastic and jelly-like. Now, thanks to the work of a self-proclaimed “eco adventurer”, we know that a species of jellyfish has found a home in the alpine nation.

Eco-adventurer allows scientists to analyse Swiss lakes

Our story starts with Noam Yaron, a self-styled adventurer and triathlete who is most famous for his long-distance runs. In August 2023, the man from Vaud crossed Switzerland and the mountains from east to west, covering 750 kilometres and climbing 13.000 metres in just one week. 

Noam explained at the time that his run was designed to raise awareness about water protection and biodiversity in Switzerland. This meant that while he was running he also took water samples from many of the alpine nation’s most famous lakes. 

These samples were then sent via the Summit Foundation - a mountain preservation association - to Swiss startup SimplexDNA, who were able to tell what species were present in the water via DNA analysis. What they found was truly astonishing.

Freshwater jellyfish colony alive and well in Lake St. Moritz

In a statement given to 20 Minuten, the Summit Foundation confirmed that there is a colony of freshwater jellyfish living in Lake St. Moritz. This is the first time jellyfish have been found living and thriving in Switzerland outside of Ticino - some invasive species of jellyfish have occasionally been found in Lake Lugano.

Called the peach blossom jellyfish (Craspedacusta sowerbii), the species originally comes from the Yangtze River in China, leading experts to speculate as to how on earth it found itself alive and well in the Engadine. “Jellyfish are often difficult to detect using traditional methods…thanks to the analysis of environmental DNA, we can identify the organisms present without direct observation,” noted Summit Foundation founder Laurent Thurnheer.

Are freshwater jellyfish harmful to humans?

The freshwater jellyfish feeds on prey by using its tentacles to poison zooplankton and other minute species. Luckily for those who fancy a dip this summer, there is no evidence to suggest that the peach blossom can actually sting a human or pierce human skin.

While not deadly to humans, the Summit Foundation noted that the jellyfish colony in St. Moritz is bound to have an impact on the local ecosystem, as the species is known to spread rapidly and in high numbers. However, in a piece of good news, they found that the invasive quagga mussels that have devastated habitats in other Swiss lakes were not detected in Lake St. Moritz.

Noam Yaron likely off to sea in 2024

The foundation concluded that Yaron’s run allowed it to analyse and better protect the local ecosystems of 10 mountain lakes. When asked by 20 Minuten where the “eco-adventurer” was off to next, Yaron said, “I can’t reveal it yet, but it will be salty.”

Jan de Boer


Jan de Boer

Jan studied in York and Sheffield in the UK, obtaining a master's in broadcast journalism and a bachelor's in history. He has worked as a radio DJ, TV presenter, and...

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