Irukandji Jellyfish

Awww! Look at that teeny, tiny, little jellyfish! Isn't it adorable?

Of course it is! It's just a shame about the killing...

Irukandji Jellyfish is the name given to Carukia barnesi, Malo kingi and any other box jellyfish that causes Irukandji syndrome. "Irukandji" refers to an aboriginal people who live on part of the northern coast of Australia, a similar distribution to the jellyfish. The "syndrome" part is a lot less sunny.

Irukandji syndrome is caused by the jellyfish's sting. At first it feels like little more than a mosquito bite, but the symptoms grow increasingly severe over the next 30 minutes or so. Eventually there are severe pains and headaches, terrible cramps in the arms and legs, sweating, vomiting, increase in heart rate and blood pressure, and even a "feeling of impending doom".

That last one is sometimes appropriate because people can and have died from this syndrome. Death is far from a common result, but even a single sting can require a visit to the hospital. There is no anti-venom either, so doctors can only manage the symptoms and severe cases can take weeks to clear up completely.

One may well ask why such a titchy jellyfish is armed with this incredibly potent venom. The answer appears to be their diet of small, fast-moving fish. A single sting is all that is required to immediately disable even the most swift and agile prey.

Certainly the Irukandji Jellyfish appears to be deeply devoted to those stingers. These jellies only reach about 1 cm (0.4 in) in size, not including 4 tentacles which themselves are often only a few centimetres long.

But the tentacles can also be stretched out, sometimes to a length of up to a metre (3.3 ft). It means that an Irukandji Jellyfish's total length may be 99% tentacle!

The tentacles can actually look quite pretty, like strands of spider silk on a dewy morning. Unfortunately, those shimmering beads are actually clusters of tiny stinging cells. Irukandji Jellyfish have yet more stinging cells on their bell, which is very unusual for jellyfish and no-one really knows what they're for.

In fact, there is a huge amount that is unknown about the Irukandji Jellyfish. The life cycle is largely unknown. The exact workings of the venom is also not well understood. It isn't even known how many other species of jellyfish cause Irukandji syndrome, but it's thought that there are at least a few more out there.

Consider the fact that Jack Barnes proved Carukia barnesi to be the cause of Irukandji syndrome as recently as 1964. How? By deliberately getting himself, his son and a local lifeguard stung, sick and hospitalised.

Seems a bit drastic does it not? Lunatic, even. Why his son and a lifeguard, too?

"I'm sure there's a perfectly rational explanation for this."

The thing with these jellyfish is that they're just so small and fragile. They are at once horrifically powerful and easily broken. Tiny and transparent to the point of invisibility, but you bloody well know when you've touched one.

Sometimes it's the small things that count.