are many different types
Although jellyfish are regarded as dangerous animals in many parts of
the world, most
jellyfish are harmless to humans. There are, however, a few species in
Australian waters that can kill us, or at least make us
very sick. The infamous Australian Box Jellyfish,
Sea Wasp Jellyfish is the most poisonous animal in the world. On this
page is some information on the different types of
jellyfish in Australia, such as Box Jellyfish, Irukandji, Portuguese
Man of War and others.
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Tentacles aka Stingers
Jellyfish belong to the Phylum Cnidaria,
which also contains various types of corals, hydroids and sea anemones
with a common feature – their tentacles possess specialised stinging
cells, called nematocysts. The stinging cells are commonly used to
capture prey, not for defence against large animals or attacks on
humans. These microscopic spring-loaded stinging cells on jellyfish
tentacles are very sensitive to pressure. When they are touched,
hundreds of thousands of them are discharged to kill the prey. Often
there are species of fish that have developed anti-venom to those
stings and use the jellyfish (or sea anemone in the case of Clown
Fish), living amongst its tentacles in protection from predators.
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Australian Box Jellyfish - Sea Wasp
The most dangerous of them all is Australian Box Jellyfish. It is not
only the most venomous jellyfish in Australia, it is the most poisonous
animal in the world. Box
Jellyfish (Chironex fleckeri)
is a big jellyfish, one of the biggest in Australia, and its venom is
strong enough that it can kill many people in one
go. It has got a box-shaped body (25cm in diameter) with four corners.
Up to 15 tentacles arise from each corner, and the tentacles may be up
to 3m long. Its stings have been described as the most
painful burn the victims have ever experienced. The stings leave
burning marks on the skin and the victim will loose consciousness
rapidly and stop breathing. There are bottles of vinegar on Australian
jellyfish-frequented beaches. Vinegar is the best thing to kill the
pain and slow down the poisoning process, so if you get stung, pour
vinegar over the wounds, for at least 30 seconds, and
call the ambulance immediately - the number is 000.
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The second most dangerous jellyfish species in Australian waters is
It is a small jellyfish, only 12mm in diameter and it is transparent,
so it’s very hard to see. Like the Australian Box Jellyfish, Irukandji
has got a box-shaped body, with one tentacle attached to each corner,
which can be up to one metre long. Its sting is not painful and often
not noticed, except some local sweating and goose-bumps, but the
delayed effect about 30 minutes later includes nausea, vomiting,
sweating and anxiety. Victims usually collapse with severe back-ache
and muscle cramps. Treatment is again - pour vinegar over wounds and
call the ambulance.
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Other Different Types of Jellyfish in Australia
Other Australian jellyfish that can make you sick are Cyanea,
also called “Hair-Jelly” or “Snottie”, with a large flat body up to
30cm in diameter, and a “mop” of hair-like tentacles up to 50cm long; Physalia,
also called “Bluebottle”
or “Portuguese Man of War” or just "Man o War
Jellyfish" with an 8cm long air-filled
sack to body and a single, 1m-long tentacle; Tamoya,
aka “Fire Jelly” or “Moreton Bay Stinger” with a box-like body and one,
up to 1m-long tentacle in each corner; and Catostylus,
also called “Blubber”, a mushroom-shaped jellyfish with an up to
30cm-long body and no tentacles but “frills” or “fronds” hanging
underneath. If you get stung by one of these, they all cause
skin irritation, burning pain, and in case of Tamoya, Irukandij-type
symptoms may follow. To treat Tamoya, pour vinegar over the wounds and
call medical help if symthoms persist. With Bluebottle, Snotty and the
Blubber, vinegar is not needed, sea-water does the job but apply cold
packs, and call medical aid only if symptoms persist.
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When are the Different Types of Jellyfish Around?
Box Jellyfish and Irukandji, the most dangerous of the different types
of jellyfish in Australia, are found in Australian warm waters between
October and April, or November and May, depending on how high up north
you are – the further north, the longer the season. There are always
signs up on these northern beaches, warning you and telling you during
which months the different types of jellyfish are present.
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How to Avoid the Different Types of Jellyfish?
During the season, the life guards set up special stinger
but be aware that these nets are only to reduce the risks – small
species like Irukandji will come through these nets, and Box
Jellyfish’s 3m-long tentacles may come through them so avoid going near
the edges. Locals don’t usually swim during the season at
all, but if you want to be totally safe in the ocean, there are special
stinger suits, similar to wet-suits, which
from getting stung.
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Beach Flags Australia
Outside the season other dangers such as sharks
or rip currents may be present, so at any time of the year anywhere in
Australia, you are safest to swim between the flags
because this area is constantly watched by lifeguards.
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up flags of different colours for your information: it is OK to swim
between yellow-red flags, but a red flag means no swimming. There are
also signs with beach reports on the beaches that are guarded by life
savers and any dangers present will be noted there.
This site uses
British English, which is the English we use in Australia. You will
find words like "traveller", "harbour" and "realise", and they are all
correct in the language used in Australia.
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