The work of Hartwick and Barnes show Chironex to be a coastal jellyfish. When the air is hot and still (frequently with a gentle northerly wind, common in tropical Australia in the summer months),
they will come into very shallow waters at gently-sloping sandy beaches close to creek and river outlets where mangroves are common. Hartwick developed the life-cycle for Chironex after first breeding specimens in the laboratory,
and then discovering their polyps in a natural habitat under rocks and mangrove roots, up to 5 kilometres from the sea in mangrove-lined rivers and streams.
For these reasons Chironex are often prevalent around the mouth of these creeks, especially as these are also areas where their prey of prawns and fish occur. Similarly they like the gently sloping, sandy beaches near these creeks. Here they can swim with the tentacles trailing behind them with little fear of them `snagging' on rocks or other obstacles fishing for their prey, including the prawns and small fish that inhabit these areas. Unfortunately, these are the same areas that humans like and frequent. Chironex fleckeri have been seen and caught over rocks, but this is less common (Fenner et al 1995).
Although Chironex are common in very shallow, calm water they have also been reported out to sea in rougher waters. A surf life saver was stung in deep, rough water near Cairns in 1991 when a Chironex was washed on to the deck of the victim's surf ski while he was paddling some 200--300 m offshore. Mulcahy (1999, personal communication) also reports that they have been trawled off the bottom by trawlers a couple of kilometres offshore. This observation remains unconfirmed.
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