Reason not to go swimming #57,875

Posted: December 28, 2012 in Cnidaria

I try to avoid easy jokes on here.

Actually, that’s a lie. I love easy jokes, mainly because they are almost as easy and fun as your mum [oh, for God’s sake…Ed]. But one joke I have tried to avoid is the whole ‘Australia is full of horrible animals that will kill you’ joke. Even though it is.  

This is nothing to do with pushing myself, to write without reverting to clichés. But mainly because I think it is a tad silly. If there is one thing I wish you to take away from this blog, it is that nature is everywhere, that Her vile minions lurk everywhere, that nowhere and no-one is safe and that the only sensible course of action is to curl into a fetal ball of terror and weep hysterically.

Having said that, Australia is full of horrible animals that will kill you. And that goes double for the seas around it.

We’ve already covered the stonefish, which I thought made for a ‘cool revenge strategy’ and everyone else thought was “evidence in the inevitable trial’. Today, because I have no concept whatsoever of original thought, we’re going to cover a group of jellyfish known to biologists as ‘Cubozoa’, to others as ‘box jellyfish’ and to their victims as ‘the Evil.’

The first thing to note is that there are actually quite a lot of cubozoa (at least 36 and probably more) – it is a whole class of the cnidaria (containing jellyfish, anemones, corals and suchlike), after all. The second thing is that they are not actually true jellyfish – that honour belongs to the catchily named Scyphozoans, and the third thing is that they are quite evidently the next stage of cnidarian evolution, that will one day emerge from the depths and reap a terrible yet just harvest upon Man.

One thing you might know about Jellyfish is that they are basically floating bags of bad news that basically float around all day, vaguely hoping that something wanders into their grasp. Cubozoans are…not quite like that. For a start, they appear to actively swim and perhaps hunt ( Secondly, they have eyes and use them to avoid obstacles (Garm et al 2007) and, possibly, to hunt. In theory, these jellyfish can see you, and then actively hunt you down. (They also appear to be averse to the colour red; thus meaning a potential super-villain scheme could be to cross breed Cubozoa and bulls [is that even possible? Ed.])

At this point, in the interests of accuracy, we should probably point out that not all Cubozoa can kill you quickly yet painfully. Chirospella bart, ( for example, apparently gives only a ‘localised painful sting’, which is partially reassuring, even though a) by now we kind of expect that these jellyfish can write academic papers downplaying their lethality and b) what counts as a painful sting’ to an Australian may be ‘soul scarring pain which makes life not worth living’ to those of us whose ancestors were not transported. [Well, we’ve alienated our one Australian reader or 50% of our readership. Ed.]

However, even if most of the 36 or so Cubozoa are lovely, peaceable and boring creatures that eagerly read the Guardian, there are at least three species that can and will make you wish you had never been born. Or, if you are slightly more of a clear thinker after being exposed to agony almost beyond the ken of mortal understanding, that the jellyfish in question had never been born.

The largest species is Chinoflex fleckeri, whose bell can be around 30cm in diameter and whose tentacles can extend 3m behind the animal. This particular species is know, along with a few others (such as C. quadrigatus), as a ‘sea wasp’, as generally the victim in question is not in a position to precisely the source of their discomfort. This discomfort has been reported to feel like having red hot wires wrapped around one’s limbs; often causing victims to become hysterical with pain ( One anecdotal account has a victim being sedated with strong anesthetic, but still continuing to scream even whilst unconscious. The venom also causes potassium to leak out of Red Blood Cells, which can cause complete cardiac and respiratory failure. (

This is probably not a good time to note that the jellyfish, large though it is, is almost invisible in shallow, sunlit water.


There are actually fifty three jellyfish in this photo…(Photo credit: Wikimedia Commons)

Another bad thing to note is that these things are not just limited to Australia; various species of Cubozoa, of varying terror, crop up most places on Earth; although Oceania is still the go-to place if you wish to commit suicide in a way that involves the word ‘jelly’.

But there are two other species which prove that horror can be compressed. Indeed, it took a surprisingly long time before anyone made the connection between a mysterious illness that suddenly struck down swimmers, and two jellyfish, Malo kingi and Carukia barnesi; neither of which are larger than a centimeter cubed. These are just as invisible as C. fleckeri, but obviously being so small they are much, much harder to avoid. The sting of these animals causes Irukandji syndrome. In many cases, the initial sting is missed; the real pain coming between 20 to 50 minutes after the sting. Severe back pain starts, and then changes into waves of muscle cramps, which have been described as unbearable and coming in waves. Chest pains then start, as does continuous vomiting and an ‘incapacitating’ headache. Sometimes, heart failure may result.

A curious psychological side-effect of this is that the victim often feels a sense of impending doom, and sometimes they have even been known to ask to be killed, simply to end the fear. Slightly worryingly, a first aid guide to this notes that the first aider may share this feeling, because what you want in your first aid guide is a jaunty little reminder that you will probably fail (

Considerably more worrying is the fact that the scientist who discovered what caused Irukandji syndrome did so by stinging his own son (as well as himself in fairness), which we are willing to bet made for a few awkward family meals afterward, as well as meaning that his mother’s threats were now useless against him. (“I will dock you a week’s allowance, and your Dad will sting you with a jellyfish straight from the bowels of Hell itself”).

And on that cheerful note, see you all next year! 


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s