Irukandji Jellyfish (Carukia barnesi)

At only 1 – 2cm in diameter the Irukandji may be the smallest jellyfish in the world but its tiny size doesn’t take away from a reputation as one of the deadliest creatures of Tropical North Queensland’s coastal and reef waters. But is this status really warranted? Read on to find out the hard facts about these mysterious creatures.  

What does it look like?

Depending on the species, the length of the body can vary from 1 – 2cm for the smallest Carukia barnesi species to 15cm; although Irukandji this big are rare. The tentacles of the Carukia barnesi at thin and can reach up to 1m long. Tiny and translucent, the Irukandji is difficult to spot while swimming, diving, or snorkelling, hence why it can be referred to as an invisible danger.

Are they only found in Australia?

No, they are found throughout the world, from South East Asia, to the Caribbean, Hawaii, South Africa and even the United Kingdom. Australia is leading Irukandji research efforts, which is perhaps why the jellyfish is wrongly thought to only occur here.

Where are they found in Australia?

Irukandji are usually found in tropical waters, from Bundaberg in Queensland, up around the northern coastline of Australia, to Geraldton in Western Australia. They have been found as far south on the eastern coastline as Hervey Bay, but this is not common. They can be found both in coastal and reef waters.

When is ‘stinger season’?

Irukandji are commonly referred to as marine stingers, or stingers. Experts, however, don’t encourage the commonly-used term of ‘stinger season’ when referring to the months of November to May, as it implies jellyfish stings do not occur at other times of the year. The preference is to refer to this period as the ‘high season’ or ‘peak season’.

What are the chances of being stung?

Out of the millions of people who visit the waters of the Great Barrier Reef, a particularly bad year will yield around 50 - 100 Irukandji stings that require medical treatment. When you consider the size of the coastline, this is not a large number. And while they have the potential to be life-threatening, the chance of a sting is very, very low according to expert Dr Lisa-Ann Gershwin.  

How do you avoid being stung?

As with any beach in Australia, swim between the red and yellow flags and be sure to pay attention to any warning signs displayed. Wear a full piece lycra suit when exploring the reef. Protective clothing has been instrumental in reducing the number of potential stings per annum to very low numbers.

Is there any way to tell Irukandji are in the water?

Yes, there are. The tell-tale signs include sea lice felt in the water and clusters of salps, which look like crushed glass or ice at the high tide line. Irukandji feed on this, so it’s a strong indicator they aren’t far away. Another clue is a sustained north-easterly wind.

What is Irukandji syndrome?

While the sting itself can be mild, the symptoms – referred to as Irukanji Syndrome – can be life-threatening, however this is only in very rare cases. Symptoms can take between 5 – 45 minutes to develop after being stung and include lower backache or a headache, overall body pain, muscular cramps or shooting pains in the victim’s muscles, chest and abdomen, nausea, vomiting, breathing difficulties.

How do you treat a sting?

  • Remove the victim from the water.
  • Douse the sting area as quickly as possible with vinegar for at least 30 seconds but avoid rubbing the sting area.
  • If vinegar is not available, carefully remove tentacles and rinse well with seawater.
  • Call for media assistance as soon as possible by dialling 000.
  • While waiting for the ambulance to arrive, regularly monitor and record the victim’s pulse, breathing and conscious level. And remember, if in doubt, treat it as an Irukandji sting.


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