Box jellyfish

Possibly one of the most dangerous marine animals of Australia’s waters, the box jellyfish (Chironex fleckeri) derives its name from the box or bell shape of its body. Its 60 tentacles – equipped with millions of nematocysts, or stinging cells – extend from the body, and have the potential to inflict fatal stings to humans.

While the common minsconception is that the box jellyfish are more commonly associated with being indigenous to Australia and the Great Barrier Reef this is not actually factually correct.

Australia has been at the forefront of studying these marine animals over decades, and research scientists from all over the world arrive on the Great Barrier Reef to meet with the local experts to study and share their findings, which are then published with two main words, "Australia and the "Great Barrier Reef",thus the misconception that box jellyfish are only found in Australia.

You can be assured you have just as much chance of coming across a box jelly fish in many other countries and not just Australia.

Box jellyfish are also found in popular holiday locations such as Bali, Thailand, The Phillipines and quite a number of other countries with warm coastal waters such as South-Eastern Asia, Africa, the Gulf of Mexico, and the Indo-Pacific.

So go ahead and plan that Great Barrier Reef holiday in Australia. See our recommended snorkeling and scuba diving tours in each destination along the East Coast.

Where and when are box jellyfish found in Australia?

They are found in the waters north of Bundaberg, Queensland, up around the coast of the Northern Territory and down to Exmouth in Western Australia. They tend to inhabit river mouths and shallow coastal waters and rarely inhabit the the outer reef sites, and the Great Barrier Reef islands such as Fitzroy Island, Green Island and Dunk Island . The jellyfish season runs from around November to May in Tropical North Queensland.

What do they look like?

The box jellyfish can grow up to 38cm across the bell with up to 15 tentacles at each corner. The tentacles look flat, like fettuccini, and can contract to about 10cm or extend up to 3m.

How do they sting?

Each tentacle is packed with stinging cells that contain a tiny harpoon attached to a venom-filled bulb. And with millions of tiny harpoons on each of its 60 tentacles, it can deliver a significant amount of venom at once, causing the victim intense pain when the tentacle attaches to the skin. A sting from a box jellyfish is far more painful than that of an Irukandji.

How do you avoid getting stung?

Swim at patrolled beaches and in between the flags. Wear a full body Lycra or neoprene suit. These cover 75 – 80 per cent of your body and help to prevent sunburn.  Reef boat operators are able to provide you with lycra suits on your snorkelling day trip for your protection and enjoy the magic of the Great Barrier Reef.

What are the symptoms and is their sting fatal?

The whip-like marks from the tentacles are not only intensely painful but they will swell up and turn red. In the case of a severe sting, the victim may stop breathing and suffer a cardiac arrest.

According to Dr Lisa-ann Gershwin, jellyfish expert and curator of Australian Irukandji Stinger Data Base, there is a fatality every three to four years in Australia from a box jellyfish, compared to 20 – 50 fatalities in places such as the Philippines where education and prevention measures are not as sophisticated.

How do you treat a sting?

  • Remove the victim from the water, alert surf life-saving patrols and seek immediate medical attention by dialling 000.
  • Douse the area with vinegar to neutralise remaining stinging cells and remove any remaining tentacles from the skin.
  • Never use methylated spirit or alcohol and do not use compression bandages.
  • Monitor the patient, keeping him or her as calm as possible while waiting for medical assistance.
  • Be prepared to conduct CPR if the victim loses consciousness.
  • Stings covering more than half of one limb are considered life-threatening.


Find out more about jellyfish from Dr Lisa Ann Gershwin in our blog about Real Reef Dangers, as well as on Lisa's website at .

Great Barrier Reef Blog