Irukandji jellyfish

The Irukandji jellyfish (Carukua barnesi) is a small, extremely venomous jellyfish of the class Cubozoa that occurs worldwide. The Irukandji's sting causes symptoms collectively known as "Irukandji syndrome". They were first documented by Hugo Flecker in 1952 and named after the aboriginal Irukandji tribe of Cairns. The jellyfish itself 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 stung himself and his son. The scientific name comes partly from Barnes.

Unlike other jellyfish, the Irukandji has stingers (nematocysts) not only on its tentacles (which are arranged in clusters that look similar to drops of water), but also on its bell. Also, its venom is injected only from the tip of the stinger (cnidocyst) rather than the entire length. This is why the initial sting is mild and there is a delayed reaction as the venom exerts its effects systemically.

Very little is known about the life-cycle and venom of the Irukandji jellyfish. This is partly because it is very small and fragile. The researchers above conjectured that the venom must be so potent in order to quickly stun its prey consisting 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 has been proven to cause the syndrome.

Description
A mature Irukandji jellyfish's bell is only 12 mm by 25 mm in height (roughly the size of an adult thumbnail). It has four contractible tentacles ranging in length from 5 cm to 1 m.

Sightings
The Irukandji Jellyfish has been seen as far south as Fraser Island, an island off the Fraser Coast in Queensland, 250 kilometres north of Brisbane. It was spotted on the shores of Fraser on 25 March, 2007. Accoridng to Lisa Gershwin, they are also found in the Indian and Atlantic oceans, including locations like the south of Wales, Florida Keys and Capetown.

Irukandji syndrome
Irukandji syndrome is produced by a very small amount of venom and includes 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), headaches, nausea, restlessness, sweating, vomiting, high heart rate and blood pressure. As of March 3, 2006, no antivenom is known. The sting itself is only moderately irritating, the severe syndrome is delayed for 5–120 minutes (30 minutes on average).

When properly treated, a single sting is normally not fatal, but two people in Australia are believed to have died from Irukandji stings, greatly increasing public awareness of Irukandji syndrome. It is unknown how many other deaths from Irukandji syndrome have been wrongly attributed to other causes.

Trivia

 * Barnes, the discoverer of the jellyfish, earned an Honorable Mention in the Darwin Awards for the daring and irresponsible action of exposing himself, his son and a lifeguard, who rushed the former two to a hospital, to the potentially fatal jellyfish.
 * This jellyfish was the cause for the delay in filming for a Hollywood film, "Fool's Gold," starring Kate Hudson. Filming was taking place in Queensland, Australia, when the jellyfish was spotted, and a marine biologist was called in to assist.
 * Episode 4 of the Australia TV Series Sea Patrol (TV series) storyline was based upon the fatal sting of a Irukandji Jellyfish of its officers on board.
 * Pop-punk band Scenes From A Movie have a song titled "Irukandji" on their debut album, The Pulse.