This tiny jellyfish is one of the most dangerous animals in the world. Not simply because of its sting, which causes something called “Irukandji Syndrome”, but also because it is almost impossible to see in the water due to its small size and transparency, and its sting often goes unnoticed.
The Irukandji jellyfish can range between 0.5 – 18cm in the height of its “bell” and have tentacles as long as 1 metre. A sting from an Irukandji may cause severe pain not localised to the site of the sting, headaches, nausea, sweating, vomiting, elevated heart rate and blood pressure, and possibly pulmonary oedema (fluid on the lungs) which is potentially fatal. Most disturbingly, it can cause a psychological phenomenon which leaves the victim with a sense of impending doom.
If you suspect you may have been stung by an Irukandji it is best to seek medical treatment immediately.
Irukandji were first described in the tropical waters of Australia’s north east, but since then they have been reported in various tropical waters around the world, so don’t think your safe just because you’re swimming in Florida!