Aussies are being warned of an almost invisible ocean threat which can cause immense pain and can be fatal, with an alarming video shared by lifeguards showing just how easily it can go unseen when swimming in the water.
The venomous Irukandji jellyfish are a “tiny” 1-2cm in length, and almost completely translucent when in water, as shown by lifesavers in Far North Queensland in a clip shared on social media.
“Just a brush of a tentacle, literally not even a full square hit, can absolutely send you to hospital and typically does,” Lisa-Ann Gershwin, a biologist and jellyfish specialist, told Yahoo News Australia.
The footage was taken after it was caught at the popular Palm Cove Beach north of Cairns last month. It shows the potentially deadly jellyfish swimming alongside $2 coin for perspective. Lisa-Anne said this species is the “size of a pinky nail when fully grown”.
“This is what we mean when we say Irukandji really are THAT small!” the post on the Australian Lifeguard Service in North Queensland’s Instagram page reads.
Jellyfish stings result in ‘horrible’ Irukandji syndrome or death
The most common Irukandji species is the Carukia barnesi, which is shown in the video. And while some can grow much bigger, up to 15cm, they’re all still hard to spot — and all extremely dangerous, experts warn.
A sting from one of them can cause what’s called “Irukandji syndrome”. “It’s an absolutely dreadful constellation of symptoms that you seriously wouldn’t want,” Lisa-Anne explained.
Symptoms include severe lower back pain, nausea, vomiting, difficulty breathing, full-body cramps and spasms and a feeling of impending doom. In some cases, a sting can also cause “severe hypertension or high blood pressure” causing stroke, fluid in the lungs and even heart failure.
“This is where we see fatal cases or life-threatening cases. It’s really, really horrible,” the Tasmanian-based scientist added.
Irukandji jellyfish found across Australia, not just in Queensland
While it’s often thought Irukandji are only present in Queensland waters — with dozens of sightings and close encounters reported each year — Lisa-Anne said there have been ample sightings across the country too.
Further south along the NSW coast, there have been “dozens and dozens of confirmed stings”. Broome and Exmouth in Western Australia are also known “Irukandji hotspot places”, she said. But many people aren’t aware, which is problematic.
“What that means is that outside the tropics, people aren’t thinking about Irukandji safety, because it’s just not on their radar at all,” she said. “And so then they’re vulnerable to when it happens because they’re just simply not aware that the risk is all around them.”
Like the Irukandji, box jellyfish measure only centimetres in length and are near-invisible in the water. Both can be fatal if stung. Source: Supplied
Swimmers advised to wear protective suits in jellyfish prone areas
Across Queensland, stinger nets are present at many beaches during the high-risk marine stinger season, which runs from November to May. They were installed in the early 1980s to protect against “the world’s most venomous animal” — the deadly box jellyfish.
“It’ll kill a healthy adult in as little as two minutes,” Lisa-Anne warned of the box jellyfish.
But the trouble is, because of their “dainty size”, Irukandji can “sail right through” the nets meaning swimmers aren’t necessarily protected from them. Queensland lifesavers recommend wearing a stinger suit for extra safety.
“It might not be the trendiest look but it’s your best protection against these harmful stings,” a lifeguard warned in a Surf Life Saving Queensland safety video last month.
Key signs Irukandji jellyfish may be present in the water
Responding to the video – and the size of the killer creatures – Aussies were in disbelief.
“That’s insane. In such a big ocean, something so small could be so deadly,” one said. “Not a hope of spotting that when you’re in the water,” wrote another.
“So small and delicate yet so incredibly dangerous,” a third shared.
While stings are still considered “pretty rare” according to Lisa-Anne, it’s important to pay attention and be aware.
Knowing about the risk factors is key to ensuring safety. The lifeguards explained that “calm flat seas” and “warm currents” are often prime conditions for Irukandji, and are likely a sign they could be in the water.
Another visible indicator “of a very high-risk condition” is if you see what looks like broken glass scattered along the tideline. This is a collection of “little jelly bodies” washed ashore, and while they’re not actually Irukandji, they co-occur during an Irukandji event.
When this is evident, “do not go in the water as there will be Irukandji,” she warned.
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