Critter of the Week: Irukandji Jellyfish

Imagine a tiny, thimble-shaped creature, invisible in water - and deadly. Step up, the Irukandji jellyfish! Izzie Clarke spoke to Lisa-ann Gershwin from the Australian Marine Stinger Advisory Services about this contender for Critter of the Week...

Izzie - Name: Irukandji jellyfish, phylum: Cnidaria, location: these jellyfish exist in oceans across the world, special abilities: the power of invisibility with the silent but deadly sting. Lisa-ann Gershwin, director of the Australian Marine Stinger Advisory Services makes the case for this week’s Critter of the Week.

Lisa-ann - You may them most as pathetic globules of white washed up on the beach but jellyfish pack a punch. One that you really don’t want to mess with is the Irukandji jellyfish. These jellies cause a debilitating illness known as Irukandji syndrome, named after an Australian aboriginal tribe. Imagine a tiny thimble-shaped creature, smaller than a miniature marshmallow and invisible in water. In life, it has 4 tentacles as fine as cobwebs and a hundred times its body length.

Izzie - Cute factor: check, home-grown invisibility cloak: check, but don’t be fooled; there's a catch.

Lisa-ann - Its sting is worse than anything Hollywood has dared to imagine. Make no mistake. This tiny beast is a killer. The sting itself is often painless and leaves no mark. Half of the victims don’t even know they’ve been stung.

Izzie - The Irukandji can fire their stingers into their victim and unlike most jellyfish, you'll also find stingers on the Irukandji’s bell.

Lisa-ann - After about half an hour, severe lower back pain begins with patients often describing it as feeling like an electric drill, drilling into the back. Within minutes, relentless nausea and vomiting begin, and can persist for 12 hours. A short time later, the rest of the syndrome kicks in including difficulty breathing, sweating, full body cramps and spasms, restless legs, and a feeling of impending doom.

Izzie - And if you think that sounds bad, get a load of this…

Lisa-ann - Some species also cause severe hypertension or high blood pressure; severe enough to haemorrhage to the brain or cause heart failure. There's no anti-venom but intriguingly, intravenous magnesium stops the whole syndrome in its tracks in many cases.

Izzie - So it’s tiny, invisible, and extremely venomous. Where can I avoid this cool but cruel critter?

Lisa-ann - Even though most people have never heard of Irukandji syndrome, species that cause it are found in all the world’s oceans; from Hawaii to Boston, to the Caribbean, from southeast Asia to the south Pacific Islands. So why do I think Irukandjis are the best critters? Because anything so small, so invisible, so mysterious, and so dangerous certainly gets my respect.

Izzie - There you have it ladies and gentlemen – the ever so small and oh so dangerous, Irukandji jellyfish.