Are turtles safe to eat jellyfish Irukandji

Highly poisonous jellyfish

Portuguese galleys off Mallorca

Highly poisonous jellyfish prefer the warm waters of the tropics and subtropics. Only Portuguese galleys (Physalia physalis) - colonies of polyps that together form a jellyfish-like creature - sometimes manage to penetrate as far as our latitudes.

Strong currents in the Atlantic can drive them as far as the bathing coasts of the Canary Islands, Portugal, northern Spain and France and even as far as the English Channel.

Very rarely does the current wash them into the Mediterranean near Gibraltar. This was the case in 2018: some specimens were spotted off Ibiza and Mallorca. As a precaution, the Spanish authorities closed the affected beaches for a short time.

Because contact with Portuguese galleys can be life-threatening for people, especially swimmers. The nettle poison causes a violent pain reaction that Portuguese galleys actually use to catch and stun fish.

Swimmers are startled by the sudden severe pain, lash around, inhale salt water and run the risk of drowning. Travel doctors suspect that some unexplained swimming accidents in the open sea can be traced back to contact with Portuguese galleys.

The most dangerous killer: the sea wasp

On exotic dream beaches, vacationers have to expect poisonous box jellyfish. These jellyfish form a separate class of cnidarians. There are around 50 species. They are so called because their umbrella is not disc-shaped, but cube-shaped.

The poison from box jellyfish not only causes severe pain, as in the Portuguese galley, but also has a systemic effect on the whole body. There are massive circulatory reactions. For example, if a swimmer is treated too late after contact with a box jellyfish, the jellyfish venom can kill him.

The most poisonous box jellyfish is the sea wasp (Chironex fleckeri). It occurs in northeast Australia. The sea wasp can see well and swims very well - in contrast to other jellyfish, which tend to drift with the current. Their nettle cells contain so much poison that a single animal could theoretically kill 250 people.

Chemical hand-to-hand combat underwater

Even with highly poisonous jellyfish, a light touch of the tentacles is enough to activate their stinging cells. In a fraction of a second, a nettle thread injects the poison mixture into the skin with the help of a harpoon.

The first proteins of the poisonous cargo destroy the cell membrane and create a free path for the neurotoxins - proteins that damage the nerves.

The jellyfish poison immediately kills smaller prey such as tiny crabs or fish larvae. Larger prey such as fish are no longer able to defend themselves adequately due to the strong pain stimulus. The jellyfish can then overwhelm you more easily.

The sea wasp also uses this effective hunting method. Their preferred area are flat sandy beaches. It can also come too close to holidaymakers who take a bath. Those affected report indescribable pain that feels boiling hot.

The problem: the nettle poison of the sea wasp is significantly more poisonous than that of the Portuguese galley. In the human body, it can lead to cardiovascular failure within minutes.

The Irukandji Syndrome

Some box jellyfish cause another life-threatening poisoning called Irukandji syndrome. At first, the effects of nettle poisons are so weak that humans hardly notice them. Depending on the type of jellyfish, however, back pain, shortness of breath, sweats and cramps occur five to 40 minutes later. Extremely high blood pressure, heart failure and stroke are also possible in rare cases.

"Carukia barnesi" is the name of a species of jellyfish that triggers such reactions. There is no immediate pain stimulus upon contact with the tentacles. Researchers believe that the tiny jellyfish doesn't need this poisonous effect because it doesn't catch large, defensive fish.

Allergy sufferers have to be careful

On European beaches nobody has to fear life-threatening jellyfish poisoning: the native jellyfish species are harmless.

There are also stinging jellyfish, such as the hairy jellyfish or fire jellyfish (Cyanea capillata) in the North and Baltic Seas or the luminous jellyfish (Pelagia noctiluca) in the Mediterranean. But jellyfish injuries can usually be treated quickly in healthy people.

However, allergy sufferers should be careful: those who are allergic to animal poisons can also react to the poison of the local jellyfish with an allergic shock.