Carukia barnesiIrukandji

Geographic Range

Carukia barnesi can be found along the coastline of Northern Australia, from Broome along the western side of Australia to Rockhamptom, Queensland on the eastern side. This includes Port Douglas in North Queensland to the Whisunday Islands near Mackay. It is also found in the Cairns regions and the Great Barrier Reef. (Goggin, 2002; Carrette and Seymour, 2002; "Great Barrier Reef - Irukandji", 2010; Barnett, et al., 2005; Winkel, et al., 2003; Ávila-Soria, 2011)


Carukia barnesi, unlike its congener Chironex fleckeri, is typically found in deeper waters along reefs. ("Irukandji syndrome", 2009; "Great Barrier Reef - Irukandji", 2010; Ávila-Soria, 2011)

  • Range depth
    near surface to 10-20 m
    to ft

Physical Description

The Irukandji jellyfish is a carybdeid cubazoan, which tend to be smaller than the other type of cubozoa, the chirodropids. Individuals of this species typically reach 25 mm in diameter, however it has been documented at a diameter of 35 mm. Carukia barnesi consists of a transparent bell that is cuboidal in shape that narrows slightly towards the apex. Extending from each of the four corners of the bell is a retractable tentacle that varies in length from 50 to 500 nm. Both the tentacles, as well as the body, are covered in stinging cells called nematocysts, however, the type of stinging cells differs on these two parts of the body. This box jelly also has a primitive and transparent eye on each side of its bell. (Goggin, 2002; Underwood and Seymour, 2007; Fenner, 2005; "Great Barrier Reef - Irukandji", 2010; Ávila-Soria, 2011)

  • Range length
    20 to 35 mm
    0.79 to 1.38 in
  • Average length
    25 mm
    0.98 in


Cubozoans have a two-stage life cycle consisting of a medusa and polyp. Fertilized eggs develop into swimming planulae, which settle after a few days. The planulae develop into motile feeding polyps, which produce other budding polyps. Polyps take a few months to mature, then begin metamorphosis by resorbing tentacles. Four new tentacles and four rhopalia are formed. When the single juvenile medusa has fully metamorphosed, it contracts and swims away. (Collins, 2000; Ávila-Soria, 2011)


The mating system of the Irukandji jellyfish has yet to be recorded, but in some cubazoan species the adults release both sperm and eggs into the ocean where fertilization will occur. (Goggin, 2002)

Mature females of Carukia barnesi are defined as having fully developed oocytes. This typically occurs when the bell height exceeds 8 mm. Males are considered mature when bell height is comparable to that of mature females. (Underwood and Seymour, 2007; Goggin, 2002; Underwood and Seymour, 2007)

At this time there is no known parental care.

  • Parental Investment
  • no parental involvement


At this time the lifespan of Carukia barnesi is not known.


The Irukandji jellyfish has been found to be both fast and agile while swimming. (Goggin, 2002)

Communication and Perception

Carukia barnesi have image-forming eyes that respond to images, but have no brain to process the visual information. (Collins, 2000; Ávila-Soria, 2011)

Food Habits

As C. barnesi matures, its diet switches from invertebrates to vertebrates. Box jellyfish in general utilize a toxin to paralyze their prey. The toxin is injected into the prey by the prey triggering one of the stinging cells (nematocysts) on the jellyfish’s tentacle. Once the stinging cell is triggered, a harpoon looking coil is released which stings the prey and the toxin then flows through this hollow harpoon into the prey. The tentacle can then be retracted back into the jellyfish, bringing the prey with it towards the jellyfish’s mouth, which is located inside the bell. (Goggin, 2002; Underwood and Seymour, 2007)

  • Animal Foods
  • fish
  • other marine invertebrates


Irukandji jellyfish are small and colorless, making them difficult to find. (Ávila-Soria, 2011)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The role of Carukia barnesi in its ecosystem is currently not known.

Economic Importance for Humans: Positive

There is no known human benefit from this species except that it serves to be an interesting research specimen because of the symptoms it causes when a person is stung.

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

Usually about 30 minutes after a person is stung by C. barnesi the victim begins to experience the following symptoms: a severe back or headache, shooting pain throughout the muscles in their chest and abdomen, nausea, anxiety, restlessness, and sometimes vomiting. Occasionally fluid may fill the lungs, which if not treated could be fatal. These symptoms can last from hours to days and requires hospitalization. No conclusive information has been obtained regarding the contents of the venom, but it might contain a neurotoxin that is a neural Na+ channel activator. No antivenom has yet been developed for this species. (Carrette and Seymour, 2002; "Great Barrier Reef - Irukandji", 2010; Winkel, et al., 2003; Ávila-Soria, 2011)

  • Negative Impacts
  • injures humans

Conservation Status

Carukia barnesi has not been given special conservation status.

Other Comments

Carukia barnesi is in the Class Cubozoa, Order Carybdeida, and Family Carybdeidae. Carukia barnesi was named after Dr. Jack Barnes who was searching for the jellyfish who caused the Irukandji syndrome. He had confirmed that the jellyfish he found did cause Irukandji syndrome by stinging himself, his son, and a surf life saver, sending them all to the hospital, in 1964. It was Hugo Flecker, however, that had named the overall syndrome caused by this jellyfish, the Irukandji syndrome. (Goggin, 2002; "Irukandji syndrome", 2009; "A year's experience of Irukandji envenomation in far north Queensland", 1998; "Great Barrier Reef - Irukandji", 2010; Winkel, et al., 2003; Ávila-Soria, 2011)


Vishal Patel (author), Rutgers University, Selina Ruzi (author), Rutgers University, David V. Howe (editor), Rutgers University.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map


an animal that mainly eats meat


the nearshore aquatic habitats near a coast, or shoreline.


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


An animal that eats mainly insects or spiders.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats fish


"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).


structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).


uses sight to communicate


Australian Medical Publishing Company. 1998. A year's experience of Irukandji envenomation in far north Queensland. The Medical Journal of Australia, 169: 638-641. Accessed June 10, 2011 at

Getaway Guide. 2010. "Great Barrier Reef - Irukandji" (On-line). Barrier Reef Australia. Accessed June 10, 2011 at

2009. "Irukandji syndrome" (On-line). Dr. Luciano Schiazza. Accessed June 10, 2011 at

Barnett, F., D. Durrheim, R. Speare, R. Muller. 2005. Management of Irukandji syndrome in northern Australia. Rural and Remote Health, 5: 369. Accessed June 06, 2011 at

Carrette, T., J. Seymour. 2002. "James Cook University Tropical Australian Stinger Research Unit" (On-line pdf). Accessed June 10, 2011 at

Collins, A. 2000. "Cubozoa: Life history and ecology" (On-line). University of California Museum of Paleontology. Accessed June 11, 2011 at

Collins, A. 2009. Evolution of box jellyfish (Cnidaria: Cubozoa), a group of highly toxic invertebrates. Proceedings of the Royal Society, 277 (1680): 493-501. Accessed June 10, 2011 at

Fenner, P. 2005. Dangerous Australian box jellyfish. South Pacific Underwater Medicine Society Journal, 35: 76-83. Accessed June 10, 2011 at

Goggin, L. 2002. "Irukandji Jellyfish" (On-line). CRC Reef Research Centre. Accessed June 10, 2011 at

Underwood, A., J. Seymour. 2007. Venom ontogeny, diet and morphology in Carukia barnesi, a species of Australian box jellyfish that causes Irukandji syndrome. Toxicon, 49 (8): 1073-1082. Accessed June 06, 2011 at

Winkel, K., G. Hawdon, P. Fenner, L. Gershwin, A. Collins, J. Tibballs. 2003. Jellyfish antivenoms: past, present, and future. Journal of Toxicology, 22: 115-127. Accessed June 10, 2011 at

Ávila-Soria, G. 2011. "Molecular characterization of Carukia barnesi and Malo kingi, Cnidaria; Cubozoa; Carybdeidae" (On-line pdf). Research online at JCU. Accessed December 11, 2010 at