Dangerous Jellyfish in Cape York

You may be scared of snakes and spiders, but as elsewhere in Australia, the land animals in Cape York are not nearly as deadly as the creatures of the ocean.

Sharks claim most lives Australia-wide, but that mostly happens in southern Australia. Up here - we have two more killers in the ocean - crocodiles and jellyfish.

Crocs pose the same danger all year around, while the deadly jellyfish are most dangerous during the build-up and the Wet Season - mostly between October and May.


It is commonly known that they are not around during the rest of the year, however at least some individuals have been reported during all months of the year.



While there are many different jellyfish in Australia, the two that are deadly are Box Jellyfish and Irukandji.

The Deadly Box Jellyfish

Our infamous Box Jellyfish is known to be the most venomous animal on the Earth, with a sting that has been described as the most painful thing that the victims ever experienced.

If you get stung you need to treat the sting with vinegar, and you need antivenom as soon as possible.

Victims are also known to need first aid to keep breathing, and rapidly lose consiousness.

If you are somewhere remote in Cape York, with no means to ring an ambulance, this is not a very good situation.

It is smart to keep yourself out of the ocean water.

While Box Jellyfish can be avoided on more popular beaches where there are stinger nets (which is not the case in the remotest parts of Cape York), there is no such protection from the tiny Irukandji.

Another Dangerous Jellyfish - Irukandji

This stinger is small enough to come through the nets, and it is transparent and almost invisible.

Despite its small size its tentacles can be a metre long. And it gives you a bad sting, which can initially be unnoticed, but once the symptoms arise, they are severe.

You do need medical assistance, and again, being stung somewhere remote is not a good situation.

If you cannot get medical help it can well be life threatening.

Australian Box Jellyfish

Box Jellyfish is not only the most dangerous jellyfish in Australia.

It is famously the most poisonous creature on the Earth, with "poison so toxic it can kill a human in minutes", and "pain so severe victims have known to go to shock and drown".

It is a marine stinger that is found in the ocean water, and if its long tentacles touch you in the water, it injects poison into you - poison that attacts your skin, heart and nervous system.

If you don't drown in shock, you may die of cardiac arrest.

But let's get the terms right first.

What Is Box Jellyfish?

World-wide, the term applies to about 40 different jellyfish species (belonging to class Cubozoa).

They differ from 'true' jellyfish (class Scyphozoa) by having a box-shaped body, tentacles emerging from each corner, eyesight, a more developed nervous system and an ability to swim instead of just drifting. In other words, in many ways, they are more advanced than the Scyphozoa jellyfish.

While the most dangerous ones of them are found in Indo-Pacific, there are also others in the group, that are found in other parts of the world.

In Australia, to most people, but also in the media, the term 'box jellyfish' applies to Chironex Fleckeri - the largest and by far the most fatal of all our jellyfish.

Although there are more jellyfish that belong to the group even in Australia (Irukandji is one of them), this page is about Chironex Fleckeri - the species that to most of us in Australia is simply known as box jellyfish.

Chironex Fleckeri is transparent to pale blue and not always very easy to see in the water.

It can swim, so it can move quicker than other jellyfish.

It also has a more developed nervous sytem, and 24 eyes, some complete with a lens, cornea, iris and retina. 

It even has a very limited memory and an ability to learn.

It is the largest jellyfish in Australia, weighing up to two kilos.

It has up to 60 tentacles that can be up to three metres long.

Each tentacle has about five thousand stinging cells (nematocysts).

Where Is Box Jellyfish Found?

Box jellyfish is found in the ocean waters of northern Australia, with the southernmost recorded points near Bundaberg in the east and Shark Bay in the west.

It is not to be relied on, though, that they cannot be any further south (saltwater crocodiles have also extended further south than they used to be and while it definitely depends on shooting bans it may also depend on changes in water temperatures).

When Is Box Jellyfish Around?

It is officially known that box jellyfish, and some other dangerous jellyfish such as Irukandji, are around during the Wet Season, approximately between October and May, and the season is longer the further north you are.

But in fact, you could get stung any time of the year as stings have been reported during all months.

They prefer calm, not too deep waters but can be present in all conditions.

They seem to like river mouths and tend to be absent in coral reef. They are also (obviously) carried to the beaches by onshore breeze.
   

On Australian beaches, there are surf life savers who have an eye on all the swimmers who swim between the flags. They are there all year around but only certain hours (approximately business hours but including weekends).

Sting and Venom of Box Jellyfish

When the tentacles touch their prey, or human skin, they are triggered by chemicals that are found on the skin.

The tentacles attach themselves to the skin and the stinging cells inject poison to the body.

Box jellyfish's poison is extremely toxic because they need to kill their prey instantly - others they would have huge problems catching creatures like shrimp and small fish.

They also use it for protection from predators that include larger fish, crabs and sea turtles.

The severity of the damage depends on the health and the age of the victim, the size of the jellyfish and the amount of tentacles involved, where on the victim's body the contact occurs, how long the contact lasts, and of course how and how quickly it is treated.

The symptoms include red whip marks on the skin, burning pain that can last for weeks, respiratory distress, irregular heartbeat, shock and irrational behaviour because of the pain, and in more serious cases extensive skin damage, cessation of breathing and cardiac arrest.

Survivors describe the pain as something worse than they have ever experienced before.

How to Protect Yourself from Box Jellyfish

The best thing is of course to avoid getting stung by keeping out of their way.

During the stinger season, there are stinger nets on all busier beaches in northern Australia (that said, most Cape York beaches are not busy enough for that).

Those nets, however, give only half the protection as the tentacles of box jellyfish still come through them, and even broken off tentacles still sting.

There are also stinger suits, but they too leave your face and hands out. They do protect most of the body though.

Many locals simply don't swim in the ocean waters and use swimming pools instead. It's often tourists who use stinger nets.
   

Treatment of Stings of Box Jellyfish 

The first thing is to get the victim out of the water and pour vinegar over the wounds before ripping off the tentacles from the skin.

That's unless the victim is showing signs of cardiac arrest, in which case, of course, CPR (cardio pulmonary resuscitation) has to be done before anything else.

Once the vinegar has been poured over the wounds, which deactivates the stinging cells, tentacles are removed (like with many other jellyfish, the tentacles will still fire poison even though they have broken off, or even if the box jellyfish is dead, but vinegar deactivates them).

Do not rub the skin, it will stimulate the stinging cells.

After that, a second lot of vinegar goes on.

Vinegar is by far the best and in fact the only remedy despite anything you may have heard about alcohol, ammonia, urine, fresh water, different acids and lemon juice.. Pressure immobilization bandage also has a bad effect.

There are nowadays bottles of vinegar available on all northern Australian beaches that get stingers and enough visitors.

However, it is not always the case with some more remote Cape York beaches, where you should keep out of the water anyway because of crocodiles.

In any case, it is not a bad idea to add a bottle of vinegar to your first aid kit.
After the vinegar and the removal of tentacles the ambulance should be called in case of box jellyfish.

In milder cases antihistamins, painkillers and ice may be enough to manage the effects of the venom.

In worse cases antivenin may be needed and sometimes it needs to be applied very quickly - within minutes.

At least 64 people have been killed by box jellyfish in Australia.

Irukandji Jellyfish

Irukandji is a small, dangerous jellyfish in northern Australia.

It is the second most dangerous jellyfish in Australia after box jellyfish (Chironex Fleckeri) - Australia's largest.

It is known for a combination of symptoms that are known as Irukandji syndrome.

It is known for giving extensive pain, and about 60 people a year are reported stung in Australia.

The jellyfish was hardly heard of before 2002 when two fatalities occured in north Queensland only months apart from each other.

What Kind of Jellyfish Is It?

For the most of us, there are two fatal jellyfish in Australia - the large box jellyfish and the tiny Irukandji, and that's all we need to know.

Taxonomically, though, "the large box jellyfish" above is only one species - Chironex Fleckeri - in a large group of box jellyfish - and irukandji, that in fact consists of at least two species what we know, is also part of the group.

It, too, has a box shaped body, even though much smaller - with a size of about a cubic centimetre. The two species known are Carukia barnesi and Malo kingi, but it's believed there is more.
   

Where Is Irukandji Found?

Like box jellyfish, it is found in the waters of northern Australia, and also some other places in the world.

Unlike blue-bottle that is mostly found on the eastern coast, it is found both on the western and the eastern coasts of Australia.

It's known to be quite bad in Broome, but also in north Queensland where the two fatal cases took place.

The Australian hot spot for the syndrome has been near Palm Cove north of Cairns, and the jellyfish was therefore named after the local Yirrganydji Aboriginal people.

It is often found near the coast, where the water is warmer. Climate change could enable it to move further south.

When Is Irukandji Around?

Like other dangerous Australian jellyfish, officially its season is between October and May.

However, stings can occur any time of the year.

Not a lot is known about its life cycle, mainly because it is too fragile to live in an aquarium - hitting a wall kills it. They have be born in captivity, the first one was born in Townsville.

What Does Irukandji Look Like?

Irukandji is a small jellyfish with a box shaped body about 5-10mm wide.

Like Chironex Fleckeri it has tentacles coming out from each corner of the body, the difference is that there is only one in each corner and that they are shorter - often no longer than a few centimetres but can be up to one metre long (still long for the tiny jellyfish!). 

Another difference - from all other jellyfish - is that it also has tentacles coming out from under its body.

Sting and Venom of Irukandji

Like with other jellyfish - when its tentacles touch their prey and other species, including humans, whose skin carries centrain chemicals, their stinging cells are triggered.

They attach themselves to the skin and inject poison to the body. Unlike other box jellyfish, irukandji fires poison from the tips of its stinging cells - something that causes a delayed pain reaction.

Its venom is very toxic because it needs to kill its prey - mainly small fish - very fast. Its venom has been said to be 100 times as potent as a cobra's and 1,000 times as potent as a tarantula's.

Irukandji Syndrome

Its sting causes a combination of different symptoms that are collectively called irukandji syndrome.

The initial sting is known for only a moderate pain, or even going unnoticed, but the symptoms start later (typically about 30 minutes later).

The symptoms include

- burning sensation of the skin

- headache

- vomiting, nausea, sweating

- pain in kidneys and lower back

- muscle cramps in arms and legs

- agitation, anxiety and restlessness

- very high blood pressure, rapid heart rate, abnormal heart beat

In serious cases these can develop into hypertension, toxic heart failure and pulmonary oedema (water in the lungs), which, if not treated, can be fatal.

The symptoms can last from hours to days and even weeks.

Victims usually need to be hospitalised.
   

How to Protect Yourself

Like with all jellyfish, the best prevention is to avoid ocean water altogether and swim in a swimming pool. Particularly during the stinger season.

The stinger nets that are placed on northern Australian beaches during the season, are designed for large box jellyfish (Chironex Fleckeri), not for irukandji, which comes through them (they were designed before the fatal irukandji cases).

Treatment of a Sting of Irukandji

Like with other box jellyfish, get out of the water and pour vinegar on the wounds, then remove any tentacles from your body.

There are vinegar bottles on all (except remote) north Queensland beaches.

Vinegar will deactivate the stinging cells that haven't been fired yet.

But it will not reverse the effect of any poison that has already been fired into your body, so you may still get the symptoms about half an hour later (but possibly also much earlier - starting from within minutes).

Ring the ambulance - you may need to be hospitalised. 
   

Irukandji has killed at least two people in Australia, but nobody knows how many have been misdiagnosed as for a long time the jellyfish was not known due to its small size.

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