Field Guide to Venomous and Medically Important Invertebrates ...

Figure 230. West coast sea nettle (Chrysaora fusescens). Photo: Scott Messmore.
The sea wasp or box jellyfish, Chironex fleckeri, is distributed throughout the Indo-Pacific
ocean. This jellyfish has been described as the most venomous creature on the planet and it has
been implicated in the death of over 70 victims throughout its range, although primarily around
Australia. Children are particularly vulnerable to the sting of this species. The months of
November to May are generally considered unsafe for swimming in tropical Pacific waters due
to the presence of this jellyfish and also the Irukandji (see below). Despite claims to the
contrary, the introduction of ―stinger nets‖ in an attempt to provide safe swimming areas has not
been satisfactory and several cases of stings occur each year from within netted enclosures.
Chironex prefer calm waters and tend to congregate near estuaries. They are restricted to within
1.2 miles (2 km) of the shore and are almost never found in open waters. Most stings occur on
humid days when the water is calm. On windy days, they drift down to calmer and deeper
waters below the choppy surface where unsuspecting swimmers can tread on them.
Figure 231. Box jellyfish (Chironex fleckeri). Photo: source unknown.
Severe pain is a predominant feature of a Chironex sting peakin in intensity at 15 minutes but
persisting for up to 12 hours. Rapid heartbeat and high blood pressure that begin at the onset of
envenomation are superseded by an unusually slow heartbeat, other heart anomalies, pulmonary
edema, and shock resulting from the failure of the heart to pump an adequate amount of blood.
Also, neuromuscular paralysis may lead to respiratory arrest. Loss of consciousness may ensue
rapidly and death may occur within a few minutes of being stung. The skin characteristically
shows a beaded or ladder pattern of red, purple or brown whiplash lesions with a frosty