Chironex fleckeri

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Chironex fleckeri
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Cubozoa
Order: Cubomedusae
Family: Chirodropidae
Genus: Chironex
Species: C. fleckeri
Binomial name
Chironex fleckeri
Southcott, 1956

Chironex fleckeri, (commonly known as the "box jellyfish," "marine stinger," or "sea wasp") is a highly venomous jellyfish of the class Cubozoa native to northern Australia. The name "Box Jellyfish" is somewhat misleading; not only does box jellyfish technically refer to the entire cubozoan category of which C. fleckeri is only one of about 19 different species, but they also aren't actually jellyfish; cubozoans is a separate category of creature from true jellyfish; scyphozoans.

Chironex fleckeri is best known for its sting. With tentacles covered in a high density of nematocysts with extremely powerful venom; the box jellyfish's sting causes excruciating pain and is strong enough to easily kill 60 adult humans in as little as 3 minutes. Approximately 67 to 100 deaths are believed to have been caused by the sting in the past 100 years. These things combined, the box jellyfish is considered the most dangerous and most venemous jellyfish; and possibly the most dangerous animal; in the entire world.

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[edit] Description

Chironex fleckeri is the largest of the cubozoans, with a bell growing to about the size of a basketball. Its is pale blue in color and is virtually transparent, making it difficult to see and, as such, an extra danger to swimmers. It has four clusters of 15 tentacles trailing from each of the four corners of the bell. When the jellyfish are swimming the tentacles contract so they are about 15cm long and about 5mm in diameter; when they are hunting, the tentacles are thinner and about three meters long. The tentacles are covered with a high concentration of stinging cells called nematocysts which are activated by pressure and a chemical trigger: they react to proteinous chemicals. Box jellyfish are day hunters; at night they are seen resting on the ocean floor 'sleeping'.

In common with other box jellyfish, Chironeex fleckeri have four eye-clusters with twenty-four eyes. Some of these eyes seem capable of forming images, but it is debated whether they exhibit any object recognition or object tracking, and it is not known how they process information from their sense of touch and eye-like light-detecting structures due to their lack of a central nervous system.

Chironex fleckeri live on a diet of prawns and small fish and are themselves prey to turtles; which are the only creatures known to be immune to their stings.

[edit] Distribution and habitat

The polyps are found in estuaries in northern Australia, the medusa is pelagic and is found in the coastal waters of northern Australia and adjacent areas of the tropical Indo-West Pacific, and are also found in southeastern Asia. They are not usually found on the reef.

Box jellyfish warning signpost at a Cape Tribulation beach in Queensland, Australia.
Box jellyfish warning signpost at a Cape Tribulation beach in Queensland, Australia.

[edit] Sting

As said before, Chironex fleckeri is best known for its incredibly powerful and often fatal sting. The sting produces excruciating pain accompanied by an intense burning sensation, and the venom has multiple effects attacking the nervous system, heart and skin at the same time. While an appreciable amount of venom (contact from about ten feet or three metres of tentacle) needs to be delivered in order to have a fatal effect on an adult human, the potently neurotoxic venom is extremely quick to act. Fatalities have been observed as little as four minutes after envenomation, notably quicker than any snake, insect or spider; and prompting its description as the world's deadliest venomous animal. Frequently a person swimming who gets stung will have a heart attack or drown before they can even get back to the shore or boat.

If a person does manage to get to safety; treatment must be administered urgently. Dousing a sting with vinegar immediately inhibits any nematocysts which have not been activated, but rubbing a sting exacerbates the problem. Water, urine and "Coke" have been shown to be ineffective, and in fact may only provoke the release of venom. After dousing with vinegar, rescue breaths and CPR may be required. Adhering tentacles should be removed carefully from the skin using protected hands or tweezers. Removed tentacles remain capable of stinging until broken down by time and even dried and presumably dead tentacles can be reactivated if wettened. The Australian snake bite treatment of using roller bandages to bandage the affected limb (with the aim of preventing distribution of the venom through the lymph and blood circulatory systems) was no longer recommended for box jellyfish envenomation after 2005. The change was prompted by research which showed that using bandages to achieve tissue compression provoked nematocyst discharge, despite the use of vinegar.

An antivenom to the Box Jellyfish's sting does exist. After the immediate treatment described above; it must be administered quickly. Hospitals and ambulance services near to where the jellyfish live possess it; and must be contacted as soon as possible. The jellyfish's venom is so powerful, however, that even if the victim does get to safety and have the immediate treatment given and contact the ambulance; they may die before the ambulance reaches them.

The box jellyfish is estimated to be the cause of at least one death a year in Australia, and the record has been set to about 67 or more; however this figure is somewhat questionable, since a number of those deaths can also be attributed to heart attack or drowning during a box jellyfish sting.

Chironex fleckeri and other jellyfish, including the infamous and arguably even worse Irukandji (Carukia barnesi), are abundant in the waters of northern Australia during the summer months (November to April or May), where it is believed they drift into the aforementioned estuaries to breed. Signs like the one pictured are erected along the entire length of the Queensland coast warning people of such, and few people swim during this period. Some people still do, however, putting themselves at great risk. At popular swimming spots, net enclosures are placed out in the water wherein people can swim but jellyfish cannot get in, keeping swimmers safe. The much smaller Irukandji, however, can pass through the nets. And for the Irukandji no known antivenom is available yet.

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