This Week In Zoology: What Causes Irukandji Syndrome?

For decades, a mysterious illness cropped up in the Australian summer months. People would fall prey to Nature’s Cruciatus Curse, an indescribable pain, a feeling like you are burning from the inside out and, at times, a conviction that you’re going to die that is so strong that you beg those around you to just kill you. This syndrome would last anywhere between 12 hours and 3 days, and then it would pass. While Irukandji syndrome was very rarely fatal, it was still scary enough that no one much wanted to have to go through it.

This mystery persisted until the 1960s, when physician and toxinocologist Jack Barnes told the world that this devastating syndrome was caused by the sting of a tiny, barely noticeable jellyfish.



As you can imagine, this was a tough sell. How do you convince the country and the world that this incredibly painful day from Hell could come from a little creature that you barely even notice when it stings you? So, how do you prove this far-fetched theory?


Well, according to Jack Barnes, you catch one. Then, you purposefully sting yourself, you nine-year old son, and an innocent bystander, just to make your point abundantly clear.

And so the world was convinced, and the little jellyfish was thereafter commonly referred to as the Irukandji jellyfish.

All of these years later, scientists still don’t understand how this venom works, and thus the official treatment for it remains vague and based on anecdotal evidence. Some say that magnesium helps. Others say that morphine is the only thing that will relieve the pain. Others still say that not even opioids will help much with the pain, as the venom is acting in a way that is of yet unknown. There are only two things that everyone seems to agree on:

  1. If you do get stung by an irukandji jellyfish, wash the area with vinegar as soon as possible. While this will not prevent the symptoms, it will kill any nematocysts that have not yet fired venom into your skin, thus at least somewhat mitigating the effects of the sting.
  2. The venom is not fatal to humans. Those who die from irukandji stings die from secondary causes, like a heart attack, precipitated by the extreme stress of the effects of the venom.

Another question that comes up is, why does such a tiny little jellyfish need such a powerful goddamned sting?! Surely it does not need a venom that packs a bunch so strong it can bring a grown man to his knees. It must eat things that are even smaller than itself, doesn’t it?

While we cannot say for sure, Zoologists believe that it’s size is precisely why it has such a powerfully strong venom.

If you’ve ever seen a video of a fish getting caught in the tentacles of a jellyfish, you will know that those fish do not die immediately. They struggle, twitch, and only after some minutes succumb to paralysis and death. If you are a large jellyfish with many tentacles, a twitchy prey is probably not going to do you much damage, nor are you going to lose much prey. However, if you are a tiny delicate creature like the irukandji, you cannot afford to have your prey try to rip away from you, no matter how small it is. To avoid this, you evolve to produce a venom that is so strong you kill your prey instantly, the second it crosses paths with your tentacles. That way, you not only assure that it does not get away, but you also assure that nothing accidentally rips off one of your few, precious tentacles.

So, there you have it. One of the smallest jellyfish you will ever come across is also the cause of one of the most painful, non-deadly things that can happen to you.

So of course it lives in Australia.


  1. Holms says

    Well, according to Jack Barnes, you catch one. Then, you purposefully sting yourself, you nine-year old son, and an innocent bystander, just to make your point abundantly clear.

    He only stung himself; his son and the bystander were not stung at all. Also, the bystander was a life guard, and was there specifically to observe and record the symptoms.

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