Irukandji Jellyfish ( carukia barnesi and malo kingi) are venomous jellyfish found in the marine waters near Australia. This species of jellyfish is classified as Cobozoans. Other species that come under this classification include sea wasps, box jellyfish and cubomedusae.
The Irukandji Jellyfish has a fascinating history. The Irukandji people who inhabit the coastal strip north of Cairns, Queensland suffered from a mysterious condition, the source of which could not be identified. The symptoms of this condition included severe pains at various parts of the body, typically excruciating muscle cramps in the arms and legs, severe pain in the back and kidneys, and a burning sensation of the skin and face. Apart from this there was the presence of headaches, nausea, restlessness, sweating, vomiting, high heart rate and blood pressure. This mysterious condition was first documented by Hugo Flecker in 1952, and this condition came to be known as the 'Irukandji Syndrome.'
It was only in 1964 that dr. Jack Barnes identified stings from this species of jellyfish as the cause of the Irukandji Syndrome. In fact, to prove that he was right, he captured a specimen of the jellyfish and purposely stung himself and some other people. It was only after this incident that the jellyfish was acknowledged as the cause of the symptom. It is in honor of Dr. Jack Barnes and his identification of the jellyfish that led it to be called Carukia Barnesi. The venomous jellyfish is also called Malo Kingi in honor of the American tourist, Robert King, who died from its sting.
Although, a mature C. barnesi's bell is only 12 mm by 30 mm in height, it is extremely venomous despite its tiny size. The Irukundji syndrome, which is extremely severe in nature, can be caused by extremely small amount of venom from the Irukandji jellyfish sting. The sting itself causes only minor discomfort. The severe symptoms are usually delayed by at least half and hour. This is the primary reason the sting of the jellyfish were not suspected as the cause of the Irukandji Syndrome. Once the symptoms begin, they can last for hours, or even days. In several experiments, magnesium has shown some effect on subsiding the effects of the sting. Most victims usually require hospitalization and immediate medical attention. In case of delayed medical attention, stings from Irukandji jellyfish are known to have caused human deaths.
The jellyfish injects venom into the flesh of his victim through numerous nematocysts that line its tentacles. Nematocysts are capsule-like in appearance and contain a thread coiled inside it. This thread is filled with the venom and when the tentacle feels any pressure, the nematocysts become active, the thread uncoils and fixes itself into the body of the victim releasing its toxins into the victim's flesh. It should be known however, that this is a natural reflex on part of the jellyfish and not an attempt to 'attack' humans! Jellyfish don't even have brains to plan an attack. The best measure to avoid stings from the Irukandji jellyfish is to avoid its known habitats.