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Irukandji jellyfish (// IRR-ə-KAN-jee) are the smallest and most venomous box jellyfish in the world—and one of the most venomous creatures on Earth. They inhabit the marine waters of Australia and are able to fire their stingers into their victim, causing symptoms collectively known as Irukandji syndrome. Their size is roughly a cubic centimetre (1 cm3). There are five known species of Irukandji: Carukia barnesi, Malo kingi and discovered in the 2000s and 2010s, Malo maximus, Malo filipina and Malo bella.
The symptoms of Irukandji syndrome were first documented by Hugo Flecker in 1952. They were named after the Irukandji people whose country stretches along the coastal strip north of Cairns, Queensland. The first of these jellyfish, Carukia barnesi, was identified in 1964 by Jack Barnes; to prove it was the cause of Irukandji syndrome, he captured the tiny jelly and allowed it to sting him while his son and a lifeguard observed the effects. Australian Toxinologist Jamie Seymour made a documentary about the jellyfish called 'Killer Jellyfish'.
Irukandji jellyfish are thought to live only in the northern waters of Australia. Species have been found in waters as far north as the British Isles, Japan,. Symptoms similar to Irukandji-syndrome have been observed in incidents at coastal waters of Florida, but their cause has not been identified but Carybdeidae jellyfish have been suspected. Sightings and injuries have also been recorded in the waters of Malaysia.
Irukandji jellyfish are very small with a bell about 5 millimetres (0.20 in) to 25 millimetres (0.98 in) wide (or wider) and four long tentacles, which range in length from just a few centimeters up to 1 metre (3.3 ft) in length.
Mature Irukanji typically have halo-like rings of tissue around their four tentacles. Apparently, it is the mature Irukanji that are highly poisonous. Apparent juveniles have been identified without the halo-rings, and without gonads, and have demostrated far weaker toxicity in stinging researchers. The stingers (nematocysts) are in clumps, appearing as rings of small red dots around the bell and along the tentacles.
The Irukandji's small size and transparent body make it very difficult to see in the water.
Very little is known about the life cycle and venom of Irukandji jellyfish. This is partly because they are too small and fragile requiring special handling and containment. Their venom is very powerful. Researchers conjecture that the venom possesses such potency to enable it to quickly stun its prey, which consists of small and fast fish. Judging from statistics, it is believed that the Irukandji syndrome may be produced by several species of jellyfish, but only Carukia barnesi and Malo kingi have so far been proven to cause the condition.
Most jellyfish have stingers only on their tentacles but the Irukandji also has stingers on its bell. Biologists have yet to discover the purpose of this unique characteristic. The hypothesis is that the feature enables the jellyfish to be more likely to catch its prey of small fish.
Irukandji jellyfish differ from other box jellyfish species in that they have the ability to fire stingers from the tips and inject venom. Currently, it is not known whether this is for some special purpose.
Irukandji jellyfish's stings are so severe they can cause fatal brain haemorrhages and on average send 50-100 people to the hospital annually.
It is capable of delivering a sting 100 times as potent as that of a cobra and 1,000 times stronger than a tarantula.
Irukandji syndrome is produced by a small amount of venom and induces excruciating muscle cramps in the arms and legs, severe pain in the back and kidneys, a burning sensation of the skin and face, headaches, nausea, restlessness, sweating, vomiting, an increase in heart rate and blood pressure, and psychological phenomena such as the feeling of impending doom. The syndrome is in part caused by release of catecholamines. The venom contains a sodium channel modulator.
The sting is moderately irritating; the severe syndrome is delayed for 5–120 minutes (30 minutes on average). The symptoms last from hours to weeks, and victims usually require hospitalisation. As with other box jellyfish, vinegar will deactivate unfired nematocysts on the skin but has no effect on the venom already in the body. Treatment is symptomatic, with antihistamines and anti-hypertensive drugs used to control inflammation and hypertension; intravenous opiates, such as morphine and fentanyl, are used to control the pain. Magnesium sulfate has been used to reduce pain and hypertension in Irukandji syndrome, although it has had no effect in other cases.
Irukandji jellyfish are usually found near the coast, attracted by the warmer water, but blooms have been seen as far as five kilometres offshore. When properly treated, a single sting is normally not fatal, but two people in Australia are believed to have died from Irukandji stings in 2002, during a rash of incidents, on Australia's northern coast, attributed to these jellyfish—greatly increasing public awareness of Irukandji syndrome. It is unknown how many other deaths from Irukandji syndrome have been wrongly attributed to other causes. It is also unknown which jellyfish species can cause Irukandji syndrome apart from Carukia barnesi and Malo kingi.
- Gershwin, Lisa-Ann (2007). "Malo kingi: A new species of Irukandji jellyfish (Cnidaria: Cubozoa: Carybdeida), possibly lethal to humans, from Queensland, Australia". Zootaxa (1659): 55–68. Retrieved 2010-07-23.
- Li, R. (2011). "The pharmacology of Malo maxima jellyfish venom extract in isolated cardiovascular tissues: A probable cause of the Irukandji syndrome in Western Australia". Tox Letters. 201 (201(3)): 221–9. doi:10.1016/j.toxlet.2011.01.003. PMID 21237252.
- Crew, Becky, "The Smallest and Deadliest Kingslayer in the World," October 7, 2013, Scientific American blog, retrieved Nov. 6, 2016
- Pearn, J. H. (1990). Australian Dictionary of Biography, Volume 14. Melbourne University Press. pp. 182–184. ISBN 0-522-84717-X. Retrieved 2013-10-01.
- Flecker, Hugo (1952-07-19). "Irukandji sting to North Queensland bathers without production of weals but with severe general symptoms". The Medical Journal of Australia. 2 (3): 89–91. ISSN 0025-729X. PMID 14956317.
- Barnes, J. (1964). "Cause and effect in Irukandji stingings". Med J Aust. 1: 897–904. PMID 14172390.
- "The pharmacology of Malo maxima jellyfish venom extract in isolated cardiovascular tissues: A probable cause of the Irukandji syndrome in Western Australia.". Toxicol Lett. 201 (3): 221–9. Mar 2011. doi:10.1016/j.toxlet.2011.01.003. PMID 21237252.
- National Geographic. Jellyfish Invasion. Retrieved 2013-10-02.
- James D Grady, MD (December 2003). "Irukandji-like syndrome in South Florida divers". Annals of Emergency Medicine. 42 (6): 763–766. doi:10.1016/S0196-0644(03)00513-4. PMID 14634600. Retrieved 2013-10-02.
- Tibballs, J. (December 2006). "Australian venomous jellyfish, envenomation syndromes, toxins and therapy". Toxicon. 48 (7): 830–59. doi:10.1016/j.toxicon.2006.07.020. PMID 16928389.
- Barnes, J. H. (1964-06-13). "Cause And Effect In Irukandji Stingings". The Medical Journal of Australia. 1: 897–904. ISSN 0025-729X. PMID 14172390.
- Killer Jellyfish, Oasis
- Predicting deadly Australian jellyfish movement, Australian Geographic, 13 May 2014
- The Beach: An Australian Passion, Robert Drewe - Page 176
- Carrette, Teresa; Seymour, Jamie. "Jellyfish responsible for causing Irukandji syndrome" (PDF). James Cook University. Archived from the original (PDF) on 2011-06-08. Retrieved 2011-10-02.
- Greenland, P.; Hutchinson, D.; Park, T. (March 2006). "Irukandji Syndrome: what nurses need to know". Nursing and Health Sciences. 8 (1): 66–70. doi:10.1111/j.1442-2018.2006.00255.x. PMID 16451431.
- Corkeron, M.; Pereira, P.; Makrocanis, C. (October 2004). "Early experience with magnesium administration in Irukandji syndrome". Anaesthesia and Intensive Care. 32 (5): 666–9. PMID 15535491.
- Little, M. (August 2005). "Failure of magnesium in treatment of Irukandji syndrome". Anaesthesia and Intensive Care. 33 (4): 541–2. PMID 16119507.
- Fenner, Peter J.; Hacock, John C. (2002-10-07). "Fatal envenomation by jellyfish causing Irukandji syndrome". The Medical Journal of Australia. 177 (7): 362–3. ISSN 0025-729X. PMID 12358578.
- "Hope for lethal jellyfish cure". BBC News. 2003-01-31. Retrieved 2010-05-05.
- Lewis, Wendy (2007). See Australia and Die. New Holland Publishers. ISBN 978-1-74110-583-4. Retrieved 2013-10-02.
- Seymour, Jamie; Carrette, Teresa. "Identification of cubozoans responsible for causing Irukandji syndrome". James Cook University. Archived from the original on 2008-09-19. Retrieved 2011-10-02.