Zoe Cahill’s skin is covered in red scars. They bear witness to the ordeal that the young Australian endured last year. The fact that she is still alive is nothing short of a miracle. The welts that run across her body like bloody veins come from the tentacles of a sea wasp – one of the most poisonous animals in the world. Cahill was only about 50 meters from shore in October when she encountered the creature while on holiday on the Thai island of Koh Phangan.
“A sting from this species of jellyfish can kill you in less than five minutes, and we estimate that a single animal has enough venom to kill hundreds of people,” says molecular biologist Greg Neely, who studies cnidarian toxins at the University of Sydney explored. “The sea wasp’s venom essentially punctures holes in the skin and then leads to cell death. This causes severe pain and later leads to scarring.” The poison can cause cardiovascular failure within a few minutes.
Like electricity in the body
“Western medical professionals assured my family that my chances of survival were next to zero,” Cahill wrote on Instagram, recounting the stitches and her rescue. She doesn’t know exactly how she made it to shore despite the excruciating pain. She was later told that helpers had poured liters of vinegar on her already lifeless and now completely blue body and revived her with heart massage and mouth-to-mouth resuscitation. Cahill told 9News that the sting felt “like electricity was shooting through my body.”
Box Jellyfish are the dangerous box jellyfish in their native Australia, and the name alone makes swimmers, snorkelers and surfers alike cringe. The animals are primarily native to the north and east coasts of Australia, mainly in shallow waters. However, they occur throughout the Indo-Pacific.
In Thailand in particular, there have been several fatal encounters in recent years. In 2015, a young German woman died there from a sea wasp sting. But Chironex fleckeri, its scientific name, are not the only jellyfish that can put people’s lives in danger.
Unerforschtes Irukandji-Syndrom
Just recently, another species of jellyfish caused alarm around the famous holiday island of K’gari (formerly Fraser Island): Irukandji. Within a few days, several tourists were stung, including children. The almost transparent box jellyfish (Carukia barnesi) are downright tiny and have a diameter of only one to two centimeters – but four tentacles up to a meter long. For comparison: the much larger sea wasp has 15 tentacles on each corner of its bluish swimming bell, each up to three meters long.
Those affected on K’gari had to be rescued by rescue helicopters. The mother of one of the victims said: “My son started vomiting and said he couldn’t feel his leg. It was scary.” The tricky thing: Unlike box jellyfish, the symptoms usually appear about 30 minutes late.
The jellyfish’s nettle toxins can then trigger what is known as Irukandji syndrome – a poisoning that can cause severe abdominal, chest and back pain as well as pulmonary edema. Without medical care, life is at risk.
“The Irukandji jellyfish probably poses the greater threat to human safety because it is so small that it cannot be seen and it is often found in less remote locations than the box jellyfish,” expert Geg Neely told Deutsche Press agency. Because of its small size, it is extremely difficult to obtain enough poison for scientific study. “Therefore, much less is known about the Irukandjis and Irukandji syndrome.”
Antivenom study
It’s different with the sea wasp: In 2019, Neely and a team succeeded in producing an agent that can block the effects of the toxin. However, it must be administered within 15 minutes of nettle exposure. Using a specific type of genetic research, the researchers found out which cells were affected by the poison and which survived – the antidote worked in mice. However, to date there has been no clinical study in humans.
According to Neely, the responsible authorities have so far shown reluctance given the high costs of such a study. “Very few people are stung by box jellyfish in Australia every year,” he says. Instead, scientists were advised to find antidotes for toxins that affect more people – such as those of the Portuguese galley jellyfish (Physalia physalis) or the spitting cobra. The team has now developed antidotes for both toxins, says Neely.
50 meter long tentacles
Portuguese galleys, which occur not only in the Pacific but also off the Canary Islands and around Portugal, are also highly poisonous jellyfish. They have even been spotted off Mallorca.
These are not real jellyfish, but rather huge polyp colonies in which each individual performs a specific task. Anyone who comes into contact with the tentacles, which are up to 50 meters long, will also suffer severe pain and red welts on the skin. For humans, an encounter with the cnidarian is rarely fatal – except in the case of an allergic shock.
Neely herself has also been stung by a Portuguese galley. It didn’t have any serious consequences for him, but the fear was great. “What’s so fascinating to me is that Australia has all these crazy, deadly jellyfish that render vast swaths of our coastline completely unusable all year round – and we don’t even really know what their venoms do.”
