The Cubozoan -- Chironex fleckeri

Be careful handling this critter from Northern Australia! Chironex fleckeri grows to about the size of a human head, and has tentacles up to three meters long. A big sting from this guy can easily kill a human, with death occurring in as little as three minutes. There have been roughly 100 deaths due to Chironex stings during the past 100 years in northern Australia. However, many people have been stung and not been killed. It is likely that these cubozoans swim away when they come into contact with something as large as a human. According to Phil Alderslade, contact with six to eight meters of tentacle is necessary to deliver enough venom to kill a person. The bell of Chironex fleckeri does not have nematocysts. Fortunately, these box jellies are in the business of catching and eating fish and crustaceans.

Chironex individuals do not inhabit reef environments. Instead, the only polyps that have ever been observed in nature were living attached to the undersides of stones in an estuary of a river in northern Australia. The polyps metamorphose into juvenile medusae beginning in the austral spring (September) and continuing until the first large summer rains (usually in January). Medusae are then flushed out into the near shore waters.


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Sources:
Hamner, W. M., Jones, M. S., and P. P. Hamner. 1995. Swimming, feeding, circulation and vision in the Australian box jellyfish, Chironex fleckeri (Cnidaria,:Cubozoa). Marine and Freshwater Research 46 (7): 985-990.

Hamner, William, M. 1994. Australia's box jellyfish, a killer down under. National Geographic. August 1994.

Hartwick, R. F. 1991. Distributional ecology and behaviour of the early life stages of the box-jellyfish Chironex fleckeri. Hydrobiologia 216/217, 181-188.

Kinsey, Barbara. 1985. Barnes on box jellyfish. published by James Cook University of North Queensland.

Kinsey, Barbara. 1988. More Barnes on box jellyfish. published by James Cook University of North Queensland.