Numerous findings of string jellyfish in Sweden
Winter swimmers along the Swedish west coast are being warned about the string jellyfish – also called "long stringy stingy thingy", and in Norway it has caused major problems in salmon farms. The up to 30 metres long stinging cnidarian has attracted much attention after Christin Appelqvist, a marine biologist at Tjärnö Marine Laboratory, encountered the species on a jetty. Since then, many finds have been reported by the public.
Why is the string jellyfish appearing now?
“This is difficult to answer. It's a native species that thrives in cold weather, but it's unusual for it to appear on this scale. The first time something like this was reported was back in 1997, and we know that the species has increased in numbers along the Norwegian Atlantic coast in recent years. But this was the first time I saw it with my own eyes. It was very beautiful and seven metres long. And I burned myself on it.”
How did it feel?
“A bit worse than a jellyfish and the pain lasted for a day or so. It’s not really dangerous for humans, but it is for fish. They get burns that become infected, or their gills get clogged by the string jellyfish so they can't absorb oxygen. Last week, thousands of salmons were killed after the species entered fish farms in northern Norway.”
It has been described in the media as a long glowing feather boa, but what kind of animal is it really?
“The species belongs to a group called siphonophores. Unlike a jellyfish, which is a single individual, these are made up of many genetically identical individuals that form something that looks like a small train, or 'colony' as we call it. Parts of the colony swim, others pick up food, and others produce gametes. So they have a common strand, but different tasks. They grow by forming more individuals in the same chain, and can bud off at any time to form new colonies. In addition, they have the ability to emit light, just like milky seas, but its function is not known. Overall, very little is known about the species and there’s no scientific data to explain why it seems to have become more common.
If you had to guess?
“Climate change could be a contributing factor. Many scientists believe that ‘jellylike’ creatures are the winners in a more acidic ocean, with sea squirts and jellyfish taking over. Since they don’t have a calcareous skeleton, they are not disadvantaged by a low PH value. This could also be linked to fishing and the fact that there are fewer fish that eat plankton and compete for food. But this is of course speculation.
Will you follow up on the findings somehow?
“We'll see how it develops and I would very much like people to contact me if they find more, so that we can get a better picture of the occurrence. So far, there have been reports from Strömstad to Lysekil, but since we don't know what salinity levels the species can handle, it's impossible to say how far south it can travel. It also depends on ocean currents and the movement of weather systems.
I brought with me a piece of the one I found, so now I have a small colony in a jellyfish aquarium here on Tjärnö that I try to keep alive and monitor.
Does it seem to feel at home?
“Yes, it has been here for a week now and it seems to be doing well. It curls up and stretches out and is very nice to look at. And maybe it has already become a bit longer.”
Writer: Per Adolfsson
Translation to English: Annika Wall
