- Also called:
- doom jellyfish
- Related Topics:
- box jellyfish
- Venom
Irukandji jellyfish
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What is an Irukandji jellyfish?
The Irukandji jellyfish are any of at least 16 species of box jellyfish known for their small size, transparency, and highly venomous stings. They are primarily found in the warm waters along the northern coasts of Australia, especially in the Coral Sea along Queensland. Some species inhabit parts of the tropical Atlantic, Indian, and Pacific oceans. The body of the Carukia barnesi, a common Irukandji jellyfish, is a boxlike transparent bell measuring 1–3.5 cm in diameter. Though the bell is densely packed with nematocysts, the venom delivered by the tentacles is more likely to cause Irukandji syndrome.
Irukandji syndrome is caused by venom delivered by nematocyst stings. The condition may manifest as excessive perspiration, muscle cramps, abdominal and back pain, vomiting, hypertension, agitation, and a sense of impending doom.
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Where are Irukandji jellyfish found?
Irukandji jellyfish, a group of small, transparent box jellyfish, are known for their highly venomous stings. They are mainly found in the warm waters off the northern coasts of Australia, especially in the Coral Sea along Queensland. Some species can also be found in parts of the tropical Atlantic, Indian, and Pacific oceans.
Carukia barnesi, a species of Irukandji jellyfish, lives primarily in deeper waters, up to around 20 meters, near coral reefs off the coast of Queensland and other parts of northern Australia. Specimens have been found in inshore waters as far south as Sydney and Melbourne. These jellyfish are planktonic, and wind and ocean currents often bring them closer to shore, particularly during the warmer months from November to May.
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Why are Irukandji jellyfish considered dangerous?
Irukandji jellyfish are dangerous because of their highly venomous stings, which can cause Irukandji syndrome. This syndrome is characterized by symptoms such as severe muscle cramps, back pain, vomiting, hypertension, and a feeling of impending doom. In severe cases, pulmonary edema, heart failure, and cerebral hemorrhaging have been reported. The venom is delivered through nematocysts, tiny poison-filled barbed hooks on the jellyfish's tentacles. Although the sting itself is mild, the effects can be life-threatening, with symptoms typically appearing about half an hour after envenomation.
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How can someone recognize or identify an Irukandji jellyfish?
Irukandji jellyfish are small, transparent box jellyfish, with at least 16 species, known for their highly venomous stings. Carukia barnesi is the species most often associated with Irukandji syndrome.
The body of the Irukandji jellyfish is a boxlike transparent bell measuring 1–3.5 cm in diameter. A single tentacle protrudes from each of the bell’s four corners, which can retract to as little as 3 cm and extend up to 1.2 meters. Each tentacle has nematocysts (capsules with tiny poison-filled barbed hooks).
Irukandji jellyfish are found primarily in deeper waters near coral reef habitats along the coast of Queensland and other parts of Australia’s northern coast. Some have been found as far south as Sydney and Melbourne.
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What symptoms do people experience if stung by an Irukandji jellyfish?
Irukandji jellyfish stings can cause Irukandji syndrome, characterized by a range of symptoms that typically start about half an hour after the sting. The symptoms may include excessive perspiration, muscle cramps, abdominal and back pain, vomiting, hypertension, and agitation. Some patients also report a sense of impending doom.
In severe cases, the syndrome can lead to pulmonary edema, heart failure, and cerebral hemorrhaging. Although the sting itself is mild and often leaves no mark, the venom delivered by nematocysts causes the condition. Symptoms usually abate after about 12 hours.
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Irukandji jellyfish, any of at least 16 species of box jellyfish (class Cubozoa) known for their transparency, small size, and highly venomous stings. The group is distributed primarily in the warm waters along the northern coasts of Australia, especially in the Coral Sea along Queensland, with some species occurring in parts of the tropical Atlantic, Indian, and Pacific oceans. Irukandji jellyfish are often associated with causing a painful and potentially life-threatening condition called Irukandji syndrome in humans; however, the syndrome is primarily associated with envenomation by the species Carukia barnesi. (For additional information on box jellyfish, including their natural history, see box jellyfish.)
Carukia barnesi
Until the 1980s, it was thought that C. barnesi was the sole Irukandji jellyfish species, so it is the one most often associated with the common name. The species is found primarily in deeper waters down to about 20 metres (about 66 feet) near coral reef habitats along the coast of Queensland and other parts of Australia’s northern coast. Some specimens, however, have been found in inshore waters as far south as the cities of Sydney and Melbourne. Irukandji jellyfish are planktonic. Wind and ocean currents drive them close to the shore throughout the year, but this happens most often during the warmer months from November to May.
The body of the Irukandji jellyfish is a boxlike transparent bell measuring 1–3.5 cm (0.4–1.4 inches) in diameter. A single tentacle protrudes from each of the bell’s four corners, which can retract to as little as 3 cm (about 1.2 inches) and extend up to 1.2 meters (3.9 feet). Each tentacle has several clusters of nematocysts (capsules with tiny poison-filled barbed hooks that can be fired into the bodies of prey). Although the bell is also densely packed with nematocysts, which occur in concentrations of 5,000 per square cm (about 775 per square inch), studies show that venom delivered by the tentacles is more likely to cause Irukandji syndrome, with that of mature individuals being the most potent.
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Other species
Several other species of Irukandji jellyfish are suspected of causing Irukandji syndrome. One of the best known is Malo kingi, sometimes known as the common kingslayer or Pseudo-Irukandji. Also found along the shores of Queensland, it is similar in size to C. barnesi; however, the presence of rings of tissue that encircle each of its tentacles distinguishes it from all other box jellyfish. Like that of C. barnesi, envenomation from this species may bring about severe cases of Irukandji syndrome that can result in the death of the victim.
Other notable Irukandji species associated with Irukandji syndrome include C. shinju, which is found along the northern coast of Western Australia and whose morphology is similar to that of C. barnesi, and M. maxima, another Western Australian species whose bell (at up to 5 cm [about 2 inches] in diameter) is slightly larger than that of M. kingi. Several species of the genus Alatina—including A. alata (found along the coasts of Florida, Puerto Rico, Hawaii, and Guam), A. moseri (found near Hawaii), and A. mordens (found near Queensland) are also considered Irukandji jellyfish.
Irukandji syndrome
The pathology was named after the Yirrganydji (or Irukandji) Aboriginal people, whose lands are located along part of the northeastern coast of Queensland, by Australian physician and natural historian Hugo Flecker in 1952. The first description of what would become known as the first Irukandji jellyfish was written in 1956; however, the species would not be formally classified as C. barnesi until 1964, after Australian physician Jack Barnes stung himself, his son, and a lifeguard with the jellyfish on purpose; shortly thereafter, all three developed Irukandji syndrome, thereby proving the causal association between the two.
Irukandji syndrome is caused by venom delivered by stings from nematocysts. The condition may present itself as excessive perspiration, muscle cramps, abdominal and back pain, vomiting, hypertension, agitation, and a sense of impending doom in the patient, or some combination of several symptoms. In severe cases, pulmonary edema, heart failure, and cerebral hemorrhaging have been reported. Symptoms typically begin about a half hour after being stung (the sting itself is mild and often leaves no mark on the victim) and abate after about 12 hours.
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Irukandji jellyfish stings occur most often in the waters surrounding Australia, and the country reports 50–100 cases of Irukandji syndrome annually. Cases of Irukandji syndrome and conditions described as “Irukandji-like syndromes” have also appeared in swimmers and divers throughout the tropics as far away as the northern Indian and central Pacific oceans, the South China Sea, the Caribbean Sea, and even the North Atlantic.