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There are many stinging animals in the sea. in
most cases their stings are annoying and their effect is short term. However, one
stinger, an Australian box jellyfish, can be very dangerous to man.
This is Chironex the largest of the Australian box
jellyfish... Chironex carries a large arsenal
of stinging cells, which contain a very potent venom.
As well as Chironex, four new species
of potentially deadly jellyfish have been discovered
on Queensland's Great Barrier Reef, posing a threat
to swimmers and divers.
Stings from the as-yet-unnamed species, which measure
from 2cm (2 inch) to 12cm (5 inch) in length, have the
same effect as the much smaller onshore irukankji jellyfish,
which cause cramps, vomiting, high blood pressure and
possible heart failure.
While it is popularly believed jellyfish only pose
a danger along the northern Australian coastline, this new research reveals
the threat offshore...it is now possible that stings
previously attributed
to the irukankji have been caused by these new species of jellyfish,
especially the three smaller ones measuring between
2cm and 4cm.
Conventional wisdom has held that the stingers are
only onshore and that the Great Barrier Reef is 100% stinger-free...
This new discovery shows this is not the case as these
irukandji appear to live on the reef. While swimmers
and divers have previously experienced such stings on
the reef, they were often dismissed as an aberration,
caused by onshore irukankji box jellyfish blowing out to
sea.
So to be sure to enjoy a yacht charter in the Whitsunday islands, it will
be necessary to be responsible and wear protective clothing.
The first thing to realise is that the Australian box jellyfish does
not deliberately attack, the problem is that we blunder
into them... There are common sense precautions you can
take to avoid box jellyfish stings.
Facts about box jellyfish
The Australian box jellyfish is a simple animal.
They have an almost cubical body (called the bell) and groups
of trailing tentacles grow from fleshy extensions at each
of the four corners of the bell - see Figure.
The trailing tentacles present the danger to man. These
can extend several metres behind an adult box jellyfish, and
can number as many as sixty in a fully mature animal.
Chironex,
largest of the Box jellies
Box jellyfish are able to manoeuvre to avoid obstacles if
they have enough time to react. They can see (poorly) with
simple eyes.
They react to the "taste" of food; prawns, small
fish etc. Once contact is made with a potential food source,
some of the stinging cells will fire and the muscles in the
tentacles will contract.
This knowledge forms the basis of two approaches which can
be taken to reduce the problem of stings on any bareboat yacht charter.
- Covering the skin provides a physical and probably
"tasteless" barrier to the stinging cells
- Pouring vinegar onto a sting prevents the firing of
additional venom into the victim.
Where the Australian box jellyfish are found
Box jellyfish have been found
on tropical shores from Darwin, through the Gulf of Carpentaria
and down the east coast of Queensland, around the Whitsunday holiday resorts and as far south as Gladstone.
It is also probable that they are to be found in the tropical
waters of Western Australia.
They are most troublesome in shallow waters and appear to
prefer beaches, which have some fresh or brackish water input.
They are often found around the mouths of creeks, and some
fatalities have occurred kilometres inside the mouths of rivers
with substantial tidal inflow.
When are Australian Box Jellyfish around?
Current knowledge indicates that November to April
are the most dangerous months in the Port Douglas to Gladstone
stretch of coast. North of Port Douglas, the season appears
to lengthen.
How visible are they?
Although relatively large, box jellyfish are virtually
invisible. Even in crystal clear water, they are difficult
to see. In our coastal waters they are nearly impossible to
see, especially when there are surface waves.
These are not like other jellyfish, which can be seen from
the beach or a boat. Even trained observers often find them
extremely difficult to find. Never assume that there are
no box jellyfish present because they 'have not been seen'.
What precautions can be taken?
There are a number of precautions you can take on bareboat sailing holidays,
which will lessen the risk of a major sting from box jellyfish.
The more precautions you take, the fewer problems should occur.
Cover up your body
An Australian box jellyfish has simple tastes and we "taste"
acceptable. Lethal stings require lots of tentacle and skin
contact. Wearing body cover minimises the amount of exposed
skin.
Any body cover which clings to the skin will give good protection.
The most important feature of any cover is that it fits firmly
at ankles, wrists, waist and neck, because it is vital that
no long tentacles can sweep against the skin through any openings.
Specially made stinger suits of lycra material give neck
to ankle protection and these can be hired in Airlie Beach in the Whitsundays and in other centres along the coast. However, other clothes can be used to
good effect, high necked skivvies with pantyhose, jeans or
exercise tights which are close fitting at the ankles.
As an interim measure lifesavers sometimes use two pairs
of pantyhose, with the feet cut out. One pair is worn conventionally,
the other pair is reversed and the swimmers arms are protected
by the pantyhose legs, with a small hole being made at the
crotch seam for the swimmer's head.
Swim at protected beaches
Some beaches have stinger nets installed and these
provide protection from large box jellyfish. Newer models
with fine mesh also protect against another tiny stranger
(Irukandji) which can also cause a swimmer to have a severe
reaction to the sting.
Avoid sudden movement
Box jellyfish can see objects in the water and can
move quite quickly to avoid them. Running, splashing violently,
and diving causes the water to swirl around a swimmer, with
the risk of bringing the tentacles into contact with the skin.
When we move quickly through the water, we do not allow
the box jellyfish time to take evasive action. Most stings
occur because people blunder into the tentacles of the jellyfish.
Avoid dangerous situations
Some places and weather conditions are particularly
hazardous. The mouths of fresh or salt water creeks are particularly
attractive to box jellyfish. Glassy still waters or gentle
ripples on the beach may bring box jellies very close inshore
to search for prawns and fish.
Always cover up when going even a short distance between
a boat and the shore, or when swimming from the shore, as
most box jellyfish stings happen in these situations.
Carry First Aid materials and
know emergency treatment
If someone is stung by a box jellyfish, the sting should
be flooded with vinegar (use at least two litres). It won't
help the pain, which is the result of some of the stinging
cells firing through the skin, but it will prevent any undischarged
stinging cells from releasing their venom, and so lessen the
risk of a fatality.
With a major sting, medical help is urgently required. If
the victim stops breathing or their heart stops artificial
respiration and heart massage (CPR) is vital and should take
precedence. To review CPR procedures look at our web pages
Emergency
techniques
If you are far from help, flood the sting with vinegar.
If you know how to immobilise a limb with splints and pressure
bandages, it will help as swimmers are usually stung on the
legs. Pressure bandages keep the venom confined to the skin
until the victim can be given expert medical attention. There
is an antivenom available, which must be administered by trained
medical personnel.
The Marine Stinger Book, published by the
Surf Life Saving Association of Australia is a useful source
of further information.
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