Beyond the Sting: The Role of Bluebottles
A bluebottle invasion at Copacabana Beach, March 2025
Yesterday, I walked along Copacabana Beach and saw more bluebottles washed ashore than I’d ever seen before. It was like the ocean had thrown a party, and these little blue drifters were the guests overstaying their welcome.
Like most beachgoers, my usual reaction to bluebottles is to avoid them at all costs—who wants to end their swim with a fiery sting?
I remember when my eldest daughter was stung in the shallows at Copacabana when she was seven. It was painful enough to turn her off the beach for almost a year. And honestly, I don’t blame her! Bluebottle stings leave an impression—literally and figuratively.
But as I stood there yesterday, watching them glisten in the sun, I found myself wondering: What are they actually good for? Surely, they have some role beyond ruining beach days.
It turns out bluebottles are far more fascinating than we give them credit for.
The Drifters of the Sea
Bluebottles (Physalia utriculus) aren’t jellyfish; they’re siphonophores (pronounced “sigh-fawn-oh-fours”). Say it out loud a few times, siphonophores, siphonophores, siphonophores. Awesome word!
Any, siphonophores are a colony of specialised organisms that work together as a single creature. That iconic blue float? It’s a gas-filled bladder that catches the wind, helping them sail across the ocean’s surface. Below, their long, trailing tentacles dangle like fishing lines, loaded with venom to catch unsuspecting prey.
Pretty alien like really.
The Role of Bluebottles in the Ecosystem
Blue dragon sea slug - one of the bluebottles biggest predators.
1. Food for the Ocean’s Hunters
While we do our best to dodge them, some sea creatures see bluebottles as a tasty treat. The blue dragon sea slug, is one of their biggest predators. This tiny, otherworldly-looking creature not only eats bluebottles but also steals their venom for its own defence. Check out the image above of the blue dragon sea slug. I have never seen these before. They are incredible! Maybe I need to research them next?
Sea turtles, particularly loggerheads, also snack on bluebottles, seemingly immune to their stings.
2. Supporting Marine Biodiversity
Bluebottles provide a floating ecosystem for small marine creatures. Tiny fish and crustaceans sometimes seek shelter around their tentacles, dodging bigger predators in the open ocean. It’s risky business, but in the vast blue, even a venomous companion can be better than none.
3. Ocean Indicators
Their presence can tell us a lot about wind and current patterns. When strong onshore winds blow, bluebottles get pushed onto our beaches in droves—like yesterday at Copacabana. Strong northeasterlies brings the blue bottles into beaches like Copa. A sudden influx might mean shifts in ocean temperatures or changing weather patterns.
A combination of overfishing bluebottles predators and warming ocean through climate change may result in an increase in bluebottle populations over time.
4. Recycling Nutrients in the Ocean and on Land
Like all ocean life, bluebottles play a role in the nutrient cycle. When they die and sink, their bodies provide food for deep-sea scavengers, feeding everything from tiny marine bacteria to larger deep-water fish. When they wash ashore, their decaying bodies become a feast for crabs, birds, and insects, recycling nutrients back into the coastal ecosystem. I wonder if these creatures will flood in for a shoreline feast at Copa sometime soon?
5. A Reminder of the Ocean’s Power
If nothing else, bluebottles remind us that the ocean isn’t a controlled swimming pool—it’s wild, untamed, and full of life. Their presence is part of the natural rhythm of the sea, a sign that we’re sharing the water with a complex, interconnected web of creatures.
What to Do If You Get Stung
If you've ever been stung by a bluebottle, you know it’s not something you forget in a hurry. Their tentacles can still sting even when detached or lying dead on the beach, so it's always best to avoid contact. But if you do get stung, here’s what to do:
Don’t rinse with freshwater – Freshwater can trigger more venom release. Instead, rinse the sting area with seawater.
Don’t rub the sting – It might seem instinctive to try and brush it off, but rubbing the sting can cause more venom to be released.
Remove any tentacles carefully – If tentacles are still stuck to your skin, use tweezers or something firm (like a credit card) to remove them. Avoid using bare hands.
Use hot water or a heat pack – Soaking the area in hot water (about 45°C) for 20 minutes can help neutralise the venom and reduce pain. If hot water isn’t available, a heat pack or even running warm water over the sting can help.
Seek medical help if needed – While bluebottle stings are rarely serious, some people may have allergic reactions or more severe pain. If symptoms worsen, seek medical attention.
Finding Wonder in the Nuisance
It’s easy to see bluebottles as just a beach hazard. But maybe, alongside caution, we can also grow in appreciation. Bluebottles, for all their sting, play an important role in the ocean’s balance. They are part of the grand design of marine life—drifting, hunting, feeding, sustaining.
That doesn’t mean I’ll be rushing into the water when they’re around, but I will look at them a little differently now. And maybe, just maybe, the next time I see one washed up on the sand, I’ll marvel at it before stepping carefully around it.
