bluebottles 1

Bluebottles – Stings and All You Need to Know

Bluebottle Physalia utriculus showing float and tentacle

The Bluebottle, (Indo-Pacific) Portuguese man of war, bloublasie and sometimes mistakenly called the bluebottle jellyfish, gets its names from its float. The float resembles a bottle or an old Portuguese man of war ship with its sails up. Although they do have canon on board, they have a vicious sting.


Bluebottles are not jellyfish and fall in the order of Siphonophores. Current scientific thinking tells us they are colonies of different multi cellular organisms. These different organisms  are structurally similar to other existing organisms that function on their own.

Each organism has become highly specialized to perform a specific task. They have lost their ability to perform other functions and are so specialized, that they cannot survive on their own, without the others.These individual organisms are known as zooids. They challenge our thinking of what we call an individual. In their case a series of individuals makes up the whole. This instead of the norm where a series of specialized cells makes up the individual. Given that all the different individual polyps originate from a single fertilized egg, there is some healthy debate on the issue.


There is also some dispute about which species is found in the Indian and Pacific oceans. Some experts say that being smaller than the Atlantic bluebottle (Physalia physalia) and having only one tentacle, that the species is Physalia utriculus.  Others say they are the same species. There does not seem to be any consensus on this. However the Atlantic bluebottles are much larger and they have much longer tentacles and have more than one tentacle. Common sense dictates that the Indian Ocean bluebottles are probably Physalia utriculus.

What is not in dispute anywhere is that it can deliver a very painful series of stings, which leave red welts wherever the tentacle has touched the skin. Having been personally stung many times I can confirm it hurts.

Bluebottle Physalia utriculus showing float and tentacle


Bluebottles have a gas filled air sac known as a pneumatophore which is muscular that is bilaterally symmetrical. It has a ridged, curved and tapered shape with the tentacles at the thick end.This keeps it afloat and provides propulsion through the wind by acting as a sail moving them down wind at an angle.

As with other organisms such as velella velalla that rely on the wind to move them, half of them have a float that twists to the right and the other half have a float that twists to the left. This causes the wind to blow each group in different directions. This adaption prevents all the individuals from an area from being blown ashore at the same time. The float which can be between six to seven centimeters long has a series of dimples across the top along the ridge. On some individuals there is a thin pink line with a bluish tint down the side. Some experts feel that they can adjust the amount of gas in the float. This changes the shape of the float to change speeds or influence direction, but there seems to be no proof of this.

The air sac has a gland that generates carbon monoxide and it has a rough 86:14 air-carbon monoxide mix in the float. They supposedly have the ability to deflate the float if necessary to avoid predators. They can then re inflate it at a later stage. On the thick end of the float is attached the gastrozooid which is the stomach. Gonozooids for reproduction and the blue tentacle with dactylozooids are also attached. The tentacle hangs down in the water to a maximum distance of around one meter. It can be retracted to bring food to the mouth.


Bluebottle tentacles have large numbers of nematocysts or stinging cells on them. These are similar to a tube that has been pulled inside out into its self with a sharp point.  They have a mechanism to pump poison through the end of the point. They are extremely small, about 0.001 mm in diameter. On the exterior there is a trigger. When this  trigger is activated the tube or tubule as it is known inverts its self, pushing outwards with force and pushing the point into the prey. It then pumps poison into the prey.

Research done in Hawaii using an electron microscope tells us that the tentacle has muscles running down it and that only one side of the tentacle, opposite the muscle has stinging cells on it. There are two types of stinging cells, larger ones (which are more prevalent at the top of the tentacle) and smaller ones interspersed in a well ordered pattern.


The tubules which deliver the venom by pushing into the prey, taper towards the tip which is sharp and both the large and small stinging cells have three rows of cat claw shaped projections on the tubule facing towards the base. These run spirally around the tubule towards the point and decrease in size towards the end of the tubule stopping just short of the sharp end. These claws hook into the prey allowing the tentacle to hold onto it and to later pull it up to the stomachs.

Research on the Atlantic bluebottle Physalia physalia has shown that it has two types of stinging cells and that each has a different type of venom. The venom is probably very similar to that of Physalia utriculus and contains a neurotoxin which attacks nerves and is also mytoxic meaning that it attacks muscle tissue. The principle components are glutamic acid, phopholipase A, and phospholipase B.

bluebottle, Physalia utriculus showing float and tentacle


They are found on the east coast of Africa from Durban in the south to the Red sea, eastwards to the mid Pacific including most islands. They live in the open ocean in large groups and are moved around by the wind.

bluebottle, Physalia utriculus washed up on beach


The bluebottle is a carnivore and it hangs its tentacle downwards and when it encounters its prey, it stings and attaches to it . These are usually small fish or plankton. The tentacle stings the prey and attaches to them with the point and the claws. The tentacle then moves the prey up to its stomachs by contracting its self. The stomachs then spread over the prey and enlarge, secreting digestive enzymes. These enzymes digest the prey and then absorb the nutrients.

Among their predators are Sunfish and loggerhead turtles.


It is rather difficult to logically get ones head around how the four different colonial organisms reproduce, given that they all come from a single fertilized egg. However theoretically you get male and female bluebottles. The gonozooids, a type of polyp, produces and releases either eggs or sperm into the water column. Fertilization takes place when the eggs and sperm meet. This fertilized egg then develops into a protozooid which then splits its self by budding into separate zooids. Scientifically it seems to be admitted that the growth pattern which results in the growth of each separate zooid is not well understood.

bluebottle, Physalia utriculus being washed onto beach


The first rule is of course not to get stung by a bluebottle and understanding the bluebottle and the conditions that cause them to come inshore helps. The bluebottles live offshore in very large groups and I have personally seen a group of many thousands, a meter or so apart stretching at least two hundred meters across and wide. A literal armada. They are open ocean creatures and use the wind to propel them through the water. While travelling they trawl through the water with their tentacle hoping to literally bump into prey.

Often when the wind blows towards the shore, large numbers are blown in and wash up on the beaches and into the surf zone. Depending on the size of the waves they usually broken up and washed onto the shore. Even a broken off piece of the tentacle can sting you and these are nearly impossible to spot in the surf.

 Physalia utriculus 2


On the Natal coast in South Africa you normally need a fairly strong north easterly wind to blow consistently for three days in a row to get them washing up on the beaches. This is just a basic rule of thumb. The rule is if there is an onshore wind blowing and you are in an area where there are likely to be bluebottles, then check the tide line on the shore first to see if there are any washed up. If there are bluebottles washed ashore then there are likely to be more around. They live in large groups and if there is one and the wind direction has not changed then there are more on the way. If the wind is blowing offshore then there are unlikely to be any in the vicinity.

If you are watching the tides as well then there are more likely to be bluebottles coming in on an incoming tide as the tidal movement brings them in. An outgoing tide will pull them offshore. Before going in the water it is well worth scanning the top of the tideline on the beach. If there are any bluebottles some will have washed up on the beach. They are relatively easy to spot as the sun reflects off them.


You can get stung on the beach, although it is more likely your dog or puppy will be. The tentacles even if broken off the body still have the ability to sting for a long period of time. Pieces are often washed up on the beach. If you have a small puppy and you are walking them along the tide line on the beach where everything is washed up, please take care, because a puppy will sniff and touch the tentacle. It will probably sting them on the nose. It will not be fatal but you will have a very unhappy puppy.

For those of you who cannot resist popping bubble wrap, walking down a beach with lots of bluebottles on it must be a bit of a temptation. Quite a few people are stung when they jump on a bluebottle to pop it and the tentacle flies up onto their legs. Is it possible to pop the bluebottles safely ? Yes wear shoes and a long pair of pants !

 Physalia utriculus washed up on beach

Most swimming beaches will issue warnings about bluebottles in the water. It is wise to heed these warnings. Especially if there are waves or foam on the water, bluebottles are very difficult to spot. Even if you are on the lookout for them, you often find them first by being stung. If there are bluebottles in the water it is sensible to get out. It is particularly important to get children out the water quickly if there are any bluebottles in the vicinity.


If you are stung by a bluebottle you will know about it very quickly because the pain is quite sharp. It is a burning type of pain and it hurts a lot particularly in the beginning. Luckily for us only tiny amounts of the venom are pumped into us and the quantities are actually very small. When stung there are two things you need to do very quickly.


The first thing to do is head for the shore because you do not want to be stung again and there may be a fairy remote possibility you will have an allergic reaction to the venom.


The second thing that you need to ideally do simultaneously, while heading out the water is to get the tentacle off of you. Because it carries on stinging you and pumping poison into you this is imperative. Having been stung so many times the minute I feel the sting, I immediately start getting it off me. If I am in deep water I will use my hand as a paddle to push water at the tentacle and float it off me. If I am in shallower water  I will aggressively splash it off or try to get it to float off me.

The quicker you get all of it off you the better and it makes a massive difference in terms of the pain. Its best not to touch it with your hands and rather than running around looking for tweezers and sticks I splash or wash it off  through fast movements in the water. If there is a handy rock pool nearby so much the better to get it all off by rinsing it and splashing seawater onto the sting site. This gets a lot of the smaller tubules you cannot see off. Getting it off very fast is highly recommended.


Once you have the main part of the tentacle off you it is important to understand that you still have large quantities of the minute stinging cells tubules (0.001 mm in diameter)  attached to you by the minute claws mentioned earlier. You cannot see them as they are so small and there is still poison in the tubules. After thoroughly splashing the site, it is best to find something suitable with a sharp edge. A  shell, knife edge or a credit card, lightly scraping this across the area will remove more of these tubules and there will be a lot less poison that could go into you. These early steps can save you a lot of pain.

You can run for the nearest shower on the beach and wash it off which is what most people do. Be warned that fresh water causes the stinging cells to release more venom. As the tentacle goes down you it will continue stinging you. It is highly recommended to wash the tentacle off with salt water for this reason.

Some people recommend using a handful of sand to rub the tentacle off. Quite why you would want to sand paper the sting into your skin is beyond me. This sounds like a silly idea and it is. If necessary use a shell or stick or anything sharpish that is handy to scrape it off.


You will have a thick welt with prominent red spots on it where you have been stung. Medically its called a small multiple discontinous linearerythrmatous papulesacute with an acute inflammatory reaction with sharp pain. In layman’s terms means it is a raised welt with red dots that hurts. And it does.

On the positive side the pain is about as bad as it is going to get. It doesn’t get worse and it will gradually after about fifteen minutes start to tone down. Usually after an hour the pain is mainly gone. It will irritate you for three days or so and you have to look after the area to prevent secondary infection.

Sometimes if the sting is near a joint and this has only happened to me personally when I have been stung near the groin, your lymph node will swell up and it will hurt. With me it has always gone down in an hour or two but if this occurs it is recommended that you head to a Doctor.

But none of these things will concern you much just after you have been stung, all you will be looking at doing is alleviating the pain. Not much else will be occupying your thoughts. So after you have got the tentacle off of you and scraped the area lightly to remove tubules what next ?


If you have allergies or have been stung around the neck by a bluebottle and there is any swelling then get to the nearest Lifeguards hut or Doctor very quickly. If you have quite a few stings then it is also a good idea to get to a Doctor. Having once been stung by very large numbers wrapping around my legs between my fins and my wetsuit while diving, you go into shock. I battled to swim the six hundred meters to the shore and was violently nauseous and sick when I reached the beach. I couldn’t walk for half an hour and the reaction to a large number of stings is very unpleasant. It took two days before I felt normal again.


Just in case its best to be safe and get yourself to a doctor if you have any of these symptoms. Swelling around the lips and eyes, rapid development of a rash or chest tightness.  Shortness of breath or wheezing, severe dizziness or faints or persistent sneezing or coughing. A hoarse voice, difficulty swallowing or throat tightness or any signs of shock (pale skin, rapid pulse or fainting). Fatalities have occurred but only very very rarely and you would have to be extremely unlucky for it to get that bad.


Poisons work on body mass so the smaller you are the greater the effect of a given amount of poison. Children, asthmatics and those with allergies are most at risk and need to be watched carefully if stung.


It is important to stay calm and there are quite a few options to relieve the pain. It seldom hurts much for more than an hour. Usually after fifteen minutes the pain drops off. You can take a paracetemol tablet to help with the pain. It is important to keep the wound clean to avoid any secondary infection.


New research seems to show that a lot of the old remedies do not work that well. Lets run through the options.


On the herbal side as a child growing up on the coast in Natal I was taught by my grandfather to use the leaves of the Carpobrotus deliciosus plant or the related species which all resemble each other. Where this remedy originates from no one is sure. They are  known as the sour fig, vygie or umgongozi in Natal. Unless you are in an urbanized area such as a big city, on a South African beach you can almost always find this plant somewhere nearby on the dunes of a beach. It is very distinctive and has triangular succulent leaves and purple flowers in Natal. In the Cape the related species have yellow or white flowers. They all work on the bluebottle sting.

Carpobrotus deliciosus plant 1

I was taught that the more red the leaf the better it works. Usually though when you need them in a hurry you cannot find the red leaves and just use the nearest green ones. You simply break them off and rub and squeeze the juice on the sting. It does provide relief from  personal experience. So far there is no science behind the remedy. For what its worth this plant has been taken to California in the USA for stabilizing dunes and Australia for the same purpose, where it is known as pig face and there are indigenous species of the same plant, which will likely work as well.



This a common suggestion but research seems to show that it actually aggravates the pain and no one recommends it anymore. Basically it causes the stinging cells that are still stuck in you and haven’t fired yet, to fire more venom into you. As there are likely still large numbers of poison carrying tubules still stuck in you it sounds like a bad idea.  Supposedly ambulance crews in some Australian states recommend it. If you have nothing else you may want to try it. Definitely do not use it if you have not washed all of the tentacles off.

Alcohol or mentholated spirits

These are not recommended by anyone. I am talking about the spirit type of alcohol, not downing a bottle of tequila which may be tempting. Unfortunately neither works for the pain although spirit alcohol will give temporary relief from the cooling.

Scrub’s Ammonia

This used to be used by all the lifeguards in Durban in South Africa in holiday season and appeared to work on the holiday makers and I have tried it before and it did appear to alleviate the pain for me.

Meat Tenderizers such as Aromat or paw paw juice

Some people swear by these but personally I have never tried them and there appears to be no science behind how they could work. Supposedly a water mixture with powder type meat tenderizers is the way to go.


This commonly suggested as a cure but for bluebottle stings there appears to be no scientific basis for it at all other than the fact it is warm, see below. Its one of those things that no one wants to volunteer to be tested with so perhaps that’s why no one knows. Theoretically there is some uric acid in some pee but not in others so it seems hit and miss. Try at your own risk and bear in mind people may never talk to you again.


All the research done in Australia where people get stung a lot seems to indicate that soaking in hot water  is the best cure. The hot water breaks the poisons protein chains up. They recommend soaking between 42 C and 45 C . In other words just about as hot as you can take it for 20 minutes. Most geysers are set between 55 C and 65 C to give you an idea of what really hot is. Be careful not to burn yourself and a hot shower should help if there is nothing else.

Anything a bit above body temperature is likely to give you some pain relief according to the research. Of course there isn’t much hot water on normal beaches. What you can do as a precaution especially if you have kids is take a thermos flask of hot water to the beach with you.


If there is no hot water nearby then it is recommended that you use ice or something cold. On most beaches  you can find a cold cool drink somewhere, to push on the sting on route to finding some hot water.

My ideal situation would be to get the sting off as soon as possible. Clean the site by splashing and soaking in seawater , a quick light scrape. Some juice on it from the Carpobrotus deliciosus plant and then to soak the sting site in hot water for twenty minutes.


Kingdom: Animalia
Phylum: Cnidaria
Class: Hydrozoa
Order: Siphonophora
Family: Physaliidae
Genus: Physalia
Species: P. utriculus



Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs …
By Donald G. Barceloux

The ultrastructure of nematocysts from the fishing tentacle of theHawaiian bluebottle,

Physalia utriculus

(Cnidaria, Hydrozoa,Siphonophora)

Angel A. Yanagihara, Janelle M.Y. Kuroiwa, Louise M. Oliver & Dennis D. Kunkel

Laboratory of Neurobiology, Pacific Biomedical Research Center, University of Hawaii at Manoa, 1993 East West Road, Honolulu, Hawaii 96822; Corresponding author. Tel.: +1-808-956-8328;fax:+1-808-956-6984;E-mail: angel@pbrc.hawaii.eduKey words: Physalia utriculus



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