Irukandji jellyfish
Encyclopedia
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
ous jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
that inhabit marine waters of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and which are able to fire their stingers into their victim, causing symptoms collectively known as Irukandji syndrome
Irukandji syndrome
Irukandji syndrome is a condition that is induced by venomization through the sting of Carukia barnesi, a species of Irukandji jellyfish, and other cubozoans. The condition is rarely fatal, but if immediate medical action is not taken, within only 20 minutes the victim could go into cardiac arrest...
. Its size is roughly no larger than a cubic centimetre (1 cm3). There are two known species of Irukandji: Carukia barnesi
Carukia barnesi
Carukia barnesi is a small and extremely venomous jellyfish found near Australia. Stings can result in Irukandji syndrome, and thus this species is commonly known as Irukandji jellyfish, although this name does not distinguish it from other Irukandji jellyfish such as Malo kingi.A mature C....
and the recently discovered Malo kingi
Malo kingi
Malo kingi is an Irukandji jellyfish named after victim Robert King, a tourist from the United States who died from its sting. It was first described to science in 2007, and is one of two species in genus Malo. It has some of the world's most potent venom, even though it is no bigger than a human...
.
The symptoms of Irukandji syndrome
Irukandji syndrome
Irukandji syndrome is a condition that is induced by venomization through the sting of Carukia barnesi, a species of Irukandji jellyfish, and other cubozoans. The condition is rarely fatal, but if immediate medical action is not taken, within only 20 minutes the victim could go into cardiac arrest...
were first documented by Hugo Flecker in 1952 and named after the Irukandji people whose country stretches along the coastal strip north of Cairns, Queensland
Cairns, Queensland
Cairns is a regional city in Far North Queensland, Australia, founded 1876. The city was named after William Wellington Cairns, then-current Governor of Queensland. It was formed to serve miners heading for the Hodgkinson River goldfield, but experienced a decline when an easier route was...
. The first of these jellyfish, Carukia barnesi, was identified in 1964 by Dr. Jack Barnes; in order to prove it was the cause of Irukandji syndrome, he captured the tiny jelly and allowed it to sting himself, his son, and a life guard.
Range
Irukandji jellyfish were at one time thought to be in the northern waters of Australia only. Since then, according to a National Geographic documentary on jellyfish, the species has been found in waters as far north as the British Isles, Japan, the Florida coast of the United States.Biology
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. Its venom is very powerful, 100 times as potent as that of a cobra
Cobra
Cobra is a venomous snake belonging to the family Elapidae. However, not all snakes commonly referred to as cobras are of the same genus, or even of the same family. The name is short for cobra capo or capa Snake, which is Portuguese for "snake with hood", or "hood-snake"...
and 1,000 times as potent as that of a tarantula
Tarantula
Tarantulas comprise a group of often hairy and often very large arachnids belonging to the family Theraphosidae, of which approximately 900 species have been identified. Some members of the same Suborder may also be called "tarantulas" in the common parlance. This article will restrict itself to...
. Researchers conjecture that its 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
Carukia barnesi
Carukia barnesi is a small and extremely venomous jellyfish found near Australia. Stings can result in Irukandji syndrome, and thus this species is commonly known as Irukandji jellyfish, although this name does not distinguish it from other Irukandji jellyfish such as Malo kingi.A mature C....
and Malo kingi
Malo kingi
Malo kingi is an Irukandji jellyfish named after victim Robert King, a tourist from the United States who died from its sting. It was first described to science in 2007, and is one of two species in genus Malo. It has some of the world's most potent venom, even though it is no bigger than a human...
have so far been proven to cause the condition.
Sting
The average jellyfish has stingers only on its 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.A jellyfish stinger (nematocyst) works like a long sock turned inside out and coiled like a spring. When the stingers are triggered, they are pulled right side out and uncoiled in a fraction of a second, launching themselves into the flesh of the victim that touched the jellyfish. These millions of microscopic, prolonged stingers then secrete venom from its tip, which causes a delayed pain reaction. When the enemy pulls away, the stingers are torn off the tentacles of the jellyfish, and they remain in the body of the victim.
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 syndrome
Irukandji syndrome is produced by a small amount of venom and includes severe pains at various parts of the body (typically excruciating muscle crampCramp
Cramps are unpleasant, often painful sensations caused by muscle contraction or over shortening. Common causes of skeletal muscle cramps include muscle fatigue, low sodium, and low potassium...
s 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 catecholamine
Catecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
s. 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 range from hours to weeks, and victims usually require hospitalisation. As with other box jellyfish
Box jellyfish
Box jellyfish are cnidarian invertebrates distinguished by their cube-shaped medusae. Box jellyfish are known for the extremely potent venom produced by some species: Chironex fleckeri, Carukia barnesi and Malo kingi are among the most venomous creatures in the world...
, 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 opiate
Opiate
In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant.-Overview:Opiates are so named because they are constituents or derivatives of constituents found in opium, which is processed from the latex sap of the opium poppy,...
s, such as morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...
and fentanyl, are used to control the pain. Magnesium sulfate
Magnesium sulfate
Magnesium sulfate is a chemical compound containing magnesium, sulfur and oxygen, with the formula MgSO4. It is often encountered as the heptahydrate epsomite , commonly called Epsom salt, from the town of Epsom in Surrey, England, where the salt was distilled from the springs that arise where the...
has been used to reduce pain and hypertension in Irukandji syndrome, although it has had no effect in other cases.
Irukandji 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, 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.