The Baltic Sea attracts many tourists from all over Poland and beyond every holiday season. It's no surprise – carefree lounging on the sandy beach and bathing in refreshing waves is what many of us look forward to all year. However, when planning vacations, concerns about jellyfish often arise. Are these concerns justified? Can these cnidarians really sting? Which of them can we encounter by the Polish sea? We write about this below.

Characteristics of Baltic jellyfish

The Polish sea is a body of water with rather specific conditions, with an average salinity of about 7%. Although it is not an ideal home for many jellyfish species, two of them are increasingly found in it. These are primarily the moon jellyfish (Aurelia aurita), which is already quite well known to Polish tourists. It is a species with a distinctive appearance. The gelatinous body of the jellyfish is completely transparent, as it consists of 98% water. Its diameter can be several centimeters. Like other Baltic jellyfish species, it also has stinging cells equipped with a venomous substance. However, there is nothing to fear – contact with it is completely harmless to humans. The second, although much rarer species, is the lion's mane jellyfish (Cyanea capillata).

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The largest jellyfish species in the Baltic Sea

The lion's mane jellyfish is the largest species of cnidarians found in our sea as well as worldwide. It can usually be found in deeper waters, but carried by sea currents, it also appears near the shore. Its coloration can vary – most often yellowish or bluish. Contact with it can be painful for humans – all because of the toxic venom present in its stingers. This jellyfish species can reach up to 2 meters in size, with tentacles up to 37 meters long. However, such impressive sizes are quite rare, as it usually reaches a diameter of up to 50 cm.

The issue of jellyfish and safety

The presence of jellyfish in the Baltic Sea may cause some concern. Parents worry about the safety of their children who spend long hours on the sandy shore. After all, cnidarians are primarily associated with stinging tentacles that can cause skin irritation. In reality, there is no reason to worry on our coast.

Do jellyfish in the Baltic Sea sting?

All jellyfish bodies are equipped with stinging cells containing a venomous substance called toxin. The good news is the venom of the moon jellyfish most often does not cause any noticeable effects in humans. Its stingers cannot penetrate human skin, so contact with it is practically harmless. Encountering a moon jellyfish might only result in a slight tingling or itching sensation, which quickly passes.

The situation is somewhat different with the lion's mane jellyfish, often also called the fire jellyfish. It has significantly more developed stingers which, upon contact with human skin, can release toxins. Therefore, the burns caused by it can lead to skin irritation. Nevertheless, it prefers cold waters, so it is extremely rare to appear over Polish beaches, especially during the season. If it does appear, they are small individuals whose venom does not pose a threat to life, so again, there is nothing to fear.

Does a dead jellyfish sting?

The stinging properties of jellyfish persist even after their death. The stinging cells are triggered by mechanical stimuli, such as touch or pressure. So if you spot a dead jellyfish while walking along the shore, it's best to leave it alone and observe it from a safe distance. This way, you avoid unnecessary risks.

Symptoms of jellyfish stings

The way a sting manifests largely depends on the species. The most common symptoms include:

very intense burning pain;
swelling;
redness;
blisters or red rash on the skin.

These symptoms can last for several days. It is also important to note that, just like with other animal venoms, it is possible to be allergic to cnidarian venom. In such cases, symptoms may be much more severe, may require doctor's intervention, but primarily immediate first aid is necessary for the injured person.

First aid for jellyfish stings

Contact with the lion's mane jellyfish – the only dangerous cnidarian by the Polish sea – is very unlikely. However, if a sting does occur, it is crucial to provide first aid immediately to minimize the effects of the venom. To do this, follow these steps:

Rinse the sting area with salt water, avoiding fresh water, which may activate remaining stingers.
If tentacle fragments remain on the skin, remove them using tweezers or any other tool, avoiding direct contact with the stingers.
If possible, it is worth washing the sting with 5% vinegar or warm water about 45°C, which helps alleviate pain and limit toxin effects.
Avoid rubbing the wound, using ice or alcohol.
If necessary, pain relievers and hydrocortisone creams for swelling can be used.

It is important to observe if the injured person is allergic to the venom. If symptoms such as seizures, difficulty breathing, or vomiting occur, medical help must be summoned immediately.

On which beaches are jellyfish most commonly found?

Jellyfish in the Baltic Sea are no longer a surprise to anyone. For several seasons, there has been more talk especially about swarms of moon jellyfish. They can mainly be spotted in summer when warm and salty waters favor their reproduction. The areas where they are most often found are around the Gdańsk Bay, including the Tricity area and west Pomeranian beaches.

Summary

Thousands of organisms live in the Baltic Sea waters, including cnidarians. This is a fact to consider when planning a seaside vacation. The most popular jellyfish species, the moon jellyfish, is not dangerous to humans. On the other hand, stings from the lion's mane jellyfish can have unpleasant consequences for tourists, but still do not pose a life threat. For your safety, however, it is wise to avoid contact with them and equip yourself with essential knowledge about these creatures. This will allow for a calm and safe relaxation by the sea.