The Upside Down Under
Irukandji Jellyfish


With an adult size of roughly a cubic centimetre (.06 cubic inch), Irukandji are both one of the smallest and most venomous jellyfish in the world.

Tiny, venomous and virtually invisible to the human eye, Irukandji jellyfish inflict a sting so painful that if you don’t die you may wish you had. They are able to fire their stingers into their victim, causing symptoms collectively known as Irukandji syndrome

Irukandji Jellyfish
One of the smallest and most venomous jellyfish in the world.

The jellyfish were named after the Irukandji people whose country stretches along the coastal strip north of Cairns, Queensland.

The first of these jellyfish, Carukia barnesi, was identified in 1964 by Jack Barnes; to prove it was the cause of Irukandji syndrome, he captured the tiny jelly and allowed it to sting him while his son and a lifeguard observed the effects. He was lucky and only ended up mildly sick.

Australian toxinologist Professor Jamie Seymour made a documentary about the jellyfish called 'Killer Jellyfish'.

Professor Seymour of James Cook University, told

“I cannot begin to explain how excruciating the pain is, I’ve been stung 11 times and each time I’ve ended up in hospital.

 Professor Jamie Seymour
Jellyfish expert Professor Jamie Seymour in the wake of an Irukandji sting which inflicts up to a day of excruciating pain and vomiting. Picture:

“It’s very mild to start with, then it takes about 15 to 20 minutes to kick in and it’s overall mind-numbing horrific pain.

“The last time I got stung across the top of my lip, then I got pins and needles in my feet, pain like red hot pokers in my joints and then overwhelming racking body pain and throwing up for 18 hours.”


The Irukandji jellyfish exists in the northern waters of Australia. The southern extent of the Irukandji's range on Australia's eastern coast has been gradually moving south, and this has been attributed to climate change. Scientists predict the jellyfish, of which there are at least eight species, will reach the Sunshine Coast within the next two decades.

Irukandji distribution in Australia
Irukandji distribution in Australia

Professor Seymour explains...

“Fifty years ago it was found off Cairns and Townsville, 40 years ago off the Whitsundays and 10 years ago off Fraser Island,” he said.

“It is cold-blooded and therefore likes warm waters and is coming further and further south and as water temperatures increase will reach the Sunshine Coast in my lifetime.”

The Sting & Irukandji Sydnrome

The Irukandji's sting causes symptoms which are collectively known as "Irukandji syndrome". Every summer, more than sixty people are hospitalized with this potentially fatal syndrome.

Irukandji Syndrome

Irukandji syndrome is a distressing envenoming secondary to the sting of Carukia barnesi and other, as yet unidentified, jellyfish found in coastal waters of tropical Australia. It has also been reported in Hawaii, the Caribbean, Asia and Papua New Guinea. In a small number of cases, life‑threatening hypertension and pulmonary oedema may develop. Two fatalities have been attributed to this condition in Australia. Management is symptomatic and supportive. Antivenom has not yet been developed.

Unlike most jellyfish, which have stingers only on their tentacles, the Irukandji also has stingers on its bell. Biologists have yet to discover the purpose of this unique characteristic. The hypothesis is that the feature enables the jellyfish to be more likely to catch its prey of small fish.

Irukandji jellyfish have the ability to fire stingers from the tips of their tentacles and inject venom. Their stings are so severe they can cause fatal brain haemorrhages and on average send 50-100 people to the hospital annually.

It is capable of delivering a sting 100 times as potent as that of a cobra and 1,000 times stronger than a tarantula.

There is no anti-venom in existence for the Irukandji and compounding the problem Prof Seymour says is the eight different types of the jellyfish have different venom and the venom in the juveniles of the creatures sets off a different physiological reaction to that of the adults.

Video: Australian toxinologist Professor Jamie Seymour talks about the Irukandji Jellyfish


Irukandji syndrome

Add comment

Leave a Reply

Subscribe to my blog:

Follow Me on Social Media

Click on the icons below to follow
me on your favourite social platform...

Translate Site

Blog Stats

  • 11,466 Post Visits

Your Header Sidebar area is currently empty. Hurry up and add some widgets.

Back to Top
%d bloggers like this: