At the time I originally posted this warning I had no documentation to back up my assertions. Today 12/30/09 there is an article on the BBC News website about the "Irukandji jellyfish, whose venomous sting can be lethal." This particular jellyfish appears to be found off the coasts of Australia and surrounding islands, but that may not be the limit of its range. Here is the link for the article which has a picture of it, but I'm also copying the article to this post after the link.
http://news.bbc.co.uk/2/low/asia-pacific/8434351.stm
'World's best job' man is stung
The man who landed what was dubbed "the best job in the world" as the caretaker on a tropical island off Australia has been stung by a lethal jellyfish.
Briton Ben Southall, who beat 34,000 applicants to secure the position, was stung during his last week in the job.
The culprit was the peanut-sized Irukandji jellyfish, whose venomous sting can be lethal.
In his blog, which he keeps as part of his job, he describes the incident as "a little sting on the beach".
But it was his progressive symptoms of fever, headache, lower back pain, chest tightness and high blood pressure that led doctors to diagnose the sting.
"I thought I'd done particularly well at avoiding any contact with any of the dangerous critters that consider this part of the world their home," Mr Southall writes in the latest update to his online diary.
Stinger suit
"I've avoided being boxed by a kangaroo, nibbled by a shark and bitten by a spider or a snake - but then in my final few days on Hamilton Island I fell foul of a miniscule little creature known as an Irukandji," his blog continues.
"I really should have been wearing a full stinger suit"
Ben Southall
Caretaker of Hamilton Island
The jellyfish - which struck as he descended from a jet-ski - is virtually invisible to the naked eye and can be deadly - in 2002 two tourists died after being stung.
It is so small it can pass through the nets that protect popular swimming spots in Queensland from larger jellyfish.
But Mr Southall - who has fully recovered after a dose of antibiotics and rest - admitted that he had been inadequately dressed for the excursion.
"It's not something to be messed around with. I really should have been wearing a full stinger suit, as is recommended at all beaches here this time of year," he said.
Mr Southall, 34, a charity fundraiser from Hampshire had to undergo a gruelling selection process to get the A$150,000 ($134,000) role - including swimming, snorkelling and one-to-one interviews.