How Do Jellyfish Sting?

The Science Behind the Sting

Jellyfish don’t actively hunt their prey; instead, they rely on specialized cells called cnidocytes, which contain tiny, harpoon-like structures known as nematocysts. When triggered—whether by touch or chemical signals—these microscopic barbs fire at speeds faster than a bullet, injecting venom into their target.

Each nematocyst is a pressurized capsule loaded with venom and a coiled tubule. When activated, the tubule uncoils and penetrates the skin, releasing toxins that can cause anything from a mild rash to intense pain, paralysis, or even heart failure in extreme cases.

Why Do Jellyfish Sting?

Jellyfish use their venom for two main reasons:

🔹 To Catch Prey – The venom immobilizes small fish and plankton, making them easy meals.

🔹 For Defense – If a jellyfish feels threatened, its stinging cells act as a powerful deterrent.

Which Jellyfish Pack the Most Painful Stings?

While many jellyfish stings are harmless, some species can be dangerous:

• Box Jellyfish – Found in Australian and Indo-Pacific waters, its venom can cause cardiac arrest in minutes.

• Portuguese Man o’ War – Technically not a jellyfish, but its tentacles deliver a painful and venomous sting. (Seen in the image below)

• Irukandji Jellyfish – Small but deadly, this jellyfish’s sting can cause extreme pain, vomiting, and even fatal complications.

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