Are Jellyfish Poisonous? First Aid for Jellyfish Stings and Whether They Can Be Eaten

When playing in the sea, people may be stung by beautiful jellyfish. It is said that the moment of contact feels like an electric shock, with the whole body going numb. Whether in tropical waters, temperate waters, shallow waters, the ocean at a depth of about 100 m, or even freshwater areas, they can be found. So what should you do if stung by a jellyfish? Are they poisonous? Can jellyfish be eaten?

Are jellyfish poisonous?

Being stung by a jellyfish is poisonous. The surface of a jellyfish's tentacles and tissue around the mouth has nematocysts, which contain nematocyst capsules that store venom and can fire threads through the capsules to inject venom into humans or animals, producing a variety of biological toxic effects on the cardiovascular system, blood, nerves, and muscles. Jellyfish venom has lethal activity, hemolytic activity, cardiovascular toxicity, liver toxicity, neurotoxicity, enzymatic activity, and more. After being stung, humans may experience rash, redness and swelling, itching, pain, lowered blood pressure, and even difficulty breathing, fainting, shock, and death.

What should you do if stung by a jellyfish?

1. Remove the tentacles: First, if the jellyfish's tentacles are still attached to the skin, try to remove them, but make sure the injured person does not move around. If conditions allow, wear gloves to remove them, or use thick clothing, tweezers, a small wooden stick, etc. to gently separate the jellyfish tentacles from the skin.

2. Rinse with seawater: Then rinse the stung area with seawater to inhibit the activity of unfired nematocysts on the skin. Using freshwater has the opposite effect; any action that changes the balance of salt concentration inside and outside the nematocysts may stimulate the capsules to fire and release more venom.

3. Scrape off nematocysts: If conditions allow, use a small knife, razor, card, or similar item to gently separate the nematocysts from the skin. Before scraping, applying shaving foam or soap lather works better. After scraping, rinse again with seawater, vinegar, or a saltwater solution.

4. Take medication: Finally, let the stung area dry naturally. You may take antihistamines such as diphenhydramine, or apply hydrocortisone cream. In follow-up care, clean the open wound daily and apply antibiotic ointment to prevent bacterial infection.

Can jellyfish be eaten?

There are many kinds of jellyfish; some can be eaten and some cannot. In the jellyfish family, moon jellyfish (Aurelia aurita) and edible jellyfish (Rhopilema esculentum) can be eaten. Other kinds cannot be eaten. After being pickled, edible jellyfish is a delicacy on many people's tables, but it should not be eaten in large amounts. The umbrella-shaped part of the jellyfish is what we usually eat as jellyfish skin, and the jellyfish's tentacles are jellyfish head. When buying jellyfish skin, usually choose the red kind, as the texture is relatively delicate and more savory.

What do jellyfish eat?

Jellyfish are all carnivorous, feeding on plankton, small crustaceans, polychaetes, and even small fish. Due to the mechanical and chemical stimulation of food, cnidarians extend their tentacles and release nematocysts to entangle, paralyze, and kill their prey, then send the food into their mouths.

Is edible jellyfish a jellyfish?

Edible jellyfish is a kind of jellyfish; it is classified under the class Scyphozoa, family Rhizostomatoidea, genus Rhopilema. Jellyfish include edible jellyfish and other jellyfish. Edible jellyfish is one of the largest jellyfish and is also one that can be eaten. Other jellyfish cannot be eaten; only edible jellyfish and moon jellyfish can be eaten. Edible jellyfish is not only delicious but also has a unique texture, and it also has high nutritional value, so edible jellyfish has become a delicacy on modern people's tables.

What are the most venomous jellyfish?

1. Box jellyfish: Each tentacle of a box jellyfish has enough toxin to kill 50 people, and it can stop a person's heart and lung function within 3 minutes. Since 1884, at least 5,567 people have died from this animal, and the death rate it causes is even higher than that of snakes, sharks, and saltwater crocodiles.

2. Portuguese man o' war: The lethal toxin in the Portuguese man o' war is secreted by tiny nematocysts in the tentacles. Although the toxin secreted by a single nematocyst is negligible, the accumulated toxin of thousands upon thousands of nematocysts is no less intense than that of any venomous snake in the world today.

3. Sand jellyfish: The umbrella diameter of an adult sand jellyfish is 25-60 cm, with a maximum of nearly 1 m. The outer umbrella surface is smooth, and the mesoglea is thick and hard. Its nematocysts are highly toxic. After a human is stung, the skin becomes red and swollen, painful, and itchy; in severe cases, shock and even death may occur.

4. Lion's mane jellyfish: The lion's mane jellyfish is a creature that can cause human death, but it rarely appears in places frequented by humans. The nematocysts on its tentacles contain toxic needles and venom-filled sacs. Once the venom enters the human body, it quickly causes paralysis and death.

In short, when we are stung by a jellyfish at the seaside, we must promptly begin self-rescue and pay attention to our own condition at all times. When necessary, we should go to the hospital for treatment immediately. If a child is stung, even more attention should be paid.