Late last week, an Australian couple stumbled upon a freaky scene in which thousands of Portuguese man o’ wars, also known as bluebottles, had washed up on the rocks just south of Bateman’s Bay in New South Wales. Disturbingly, it’s a sight we’re going to have to get used to in our warming world.

Brett Wallensky and his partner Claudia spotted the scene while walking along Barlings beach on Friday October 27, having spotted a few in the water earlier in the day while kayaking and observing humpback whales. The couple couldn’t get over the striking blue color of the conglomeration, describing the scene as “alien.”

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“There must have been thousands of them beached and they were all alive and wriggling,” said Wallensky in a StoryTrender post. “It was the stuff nightmares are made of. It was just horrible to look at them wriggling around and trying to sting you. If you fell in there and got that many stings all over you I can’t imagine you would survive.”

Indeed, these venomous Portuguese man o’ wars (Physalia utriculus) can be a huge annoyance, stinging hundreds of people each day around the world. Stings from these animals are very painful, but generally not life threatening. At least, not when you’re stung by just one. Falling into a mass like this would be...bad.

“I would be awed by a sight like this! It’s not often that you get to see so many of these incredible animals up close. But don’t get too close!,” Christie Wilcox, a marine biologist at the University of Hawaiʻi at Mānoa, told Gizmodo. “Bluebottles are not true jellyfish, and instead are a colonial organism in the same phylum. So they are related to jellyfish, and similarly possess a potent sting. Their stinging cells can remain active for weeks after beaching, so even if the animals are dead, they can still pack a whollop!”

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Wilcox saidthat there have been a few deaths from a related species in the Atlantic; the ones in Australia are of the smaller, less venomous Indo-Pacific variety.

“Severe cases always involve meters of stinging tentacle. Our most recent research...has found that stings from bluebottles and their relatives are best treated by rinsing with vinegar and then applying heat (45C/113F for 45 min or longer),” said Wilcox. “Seawater rinsing is not a good substitute for vinegar because it doesn’t inactivate the stingers, so you can actually make the injury worse. So if you have tentacles on you and don’t have vinegar, it’s best to carefully pluck them off. If you happen to have it, the most effective rinse and treatment are the Sting No More products.”

As for the mass beaching itself, Wilcox says this happens every so often in certain areas when conditions are right. These sea creatures, with their vivid blue sails, can be pushed around by strong winds, and strong onshore winds can shove them into the shallows.

“I don’t think there’s anything particularly special about this mass stranding of bluebottles,” Wilcox told Gizmodo. “It’s a bit hard to tell, but it looks like the location happens to be a place where debris pushed ashore clumps together naturally (like how some places on a beach get mats of seaweed while others are clear).”

That said, Portuguese man o’ wars, like jellyfish, are poised to be the greatest beneficiaries of climate change, so scenes like this could start to happen with increased frequency. As Wilcox said, this happens when “conditions are right.” In a Popular Science post from last year, marine biologist Lisa-ann Gershin explained it like this:

...climate warming...amps up jellyfish in unbelievable ways. Fractions of degree changes above normal water temperatures amp up their metabolism, they eat more and breed more and live longer — it’s astounding what a little bit of warming can do for jellyfish. Trawling gives them new room for their polyps to settle, and while acidification or chemical pollution doesn’t hurt jellyfish, it hurts everything else like fish and shellfish that struggle with environmental change.

So for those of you who like to take long walks on the beach, you’re going to have to a bit more careful.

[Sydney Morning Herald, StoryTrender]