Lay a jellyfish eggs 1

Wonder jellyfish in the Baltic Sea Food addict, fertile and almost immortal - the sea walnut

It has the shape of a walnut, is delicate, small, transparent with edges that look like zippers. On average, it only grows to five centimeters, rarely ten. Marine biologist Dr. Jamileh Javidpoor ​​from the Helmholtz Center for Ocean Research in Kiel says she is a "goo animal." The "Glibbertier" sea walnut stands between the species. It belongs neither to the real jellyfish nor to the fish, explains Javidpoor: "They are very simple animals, they have no brains, but very simple organs."

Thousands of eggs a day

Sea walnuts have a few muscles, reproductive organs, and digestive organs. The muscles only use them when they have to. Most of the time they just let themselves drift. As soon as the water gets warmer, they come out and multiply - extremely quickly. "One large sea walnut can produce thousands of eggs a day," says Javidpoor. And in order to do that, the sea walnut needs a lot of food. That wouldn't be a problem if it weren't for climate change.

Two months early this year

Usually, the animals appear in large numbers in late August, early September. But this year they are there earlier. "We saw the first specimens yesterday, three or four centimeters tall," said the marine biologist from Kiel. The reason could be the warm weather or the fact that sea walnuts feel more comfortable here from year to year. Jamileh Javidpoor ​​doesn't know exactly yet. The researchers now fear that there will not be enough food for everyone in midsummer. Because the small sea walnut eats a lot. "They can also eat all the time. That means that a large jellyfish can hold hundreds of crabs. When their stomachs are full, they spit everything out and take something again."

In their home waters, the Atlantic, the sea walnut has natural enemies. It doesn't occur that often there either. It is different in the Baltic Sea. It is only eaten there by the fire jellyfish, maybe also by a few fish. Marine biologist Javidpoor ​​isn't sure yet. Examining the stomach contents of fish has brought little, she says, because it only contains goo and it dissolves quickly.

Slime could scare bathers away

The researchers fear food shortages if the sea walnut appears so early. In addition, the bathers are frightened. At weddings, the animals produce so much eggs and slime that the water becomes thick. So far, this phenomenon has only occurred in autumn. According to Javidpoor, it was only a year or two where they had so many animals. And that was also in September. This year the bather could see more of it. But no fear. "They don't do anything," assures Javidpoor. The marine biologist is fascinated by the animals. But she cannot answer many questions yet. For example, how old the animals get: "Please don't ask that, because then I'll be completely wrong. You really don't know whether they can live forever."

In any case, the Kiel researchers expect difficulties in the Baltic Sea this year, with a lack of food and poorer water. The bathing guest can watch a new natural spectacle: the sea walnut glows blue to rainbow-colored at night.