Different Types of Jellyfish

There are many different types of jellyfish in Australia.

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, aka 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.

Life Guard, Avalon Beach, New South Wales, Australia, Pacific
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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.

Diver Observing a Lion's Mane Jellyfish, Cyanea Capillata
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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.

Box Jellyfish or Sea Wasp, Poisonous, Australia
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The second most dangerous jellyfish species in Australian waters is Irukandji (Carukia barnesi). 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.

Close Up of a Lion's Mane Jellyfish, Cyanea Capillata
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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.

Portuguese Man O' War Jellyfish, Turneffe Caye, Belize
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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.

Coolangatta Beach, Queensland, Australia
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How to Avoid the Different Types of Jellyfish?
During the season, the life guards set up special stinger nets, 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 protect you from getting stung.

Young Boy Snorkelling in Nemo Stinger Suit
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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.

Lifesaving Marker Flag on Surf Beach, Gold Coast, Queensland, Australia
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Lifeguards set 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.

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