Myth or Fact? #28 - Can jellyfish kill people?

in science •  2 years ago  (edited)

Welcome my Steemian friends to a new episode of Myth or Fact?

I visited Thailand in February and enjoyed the beautiful scenery. Fantastic beaches, crystal clear water, tropical jungle and much more are awaiting you there. On one day we wanted to visit a quite famous beach called Bottle beach. It was a rather remote place and hard to get there, it took us almost an hour walk to reach the beach. Once we arrived we understood why the beach was named after bottles. Everywhere around the beach you would see bottles, makes sense right?

I asked a local citizen why they had all these fancy bottles around the beach. His answer was quite alarming: there are many jellyfishes in the water and it happens that sometimes people die. In the bottle you will find vinegar.

My stay at the beach was quite short. Right after I heard his story we went immediately back. Wonderful: the hot sun burning on my skin, being exhausted and only wanted to relax I had to walk the hour back!

Am I exaggerating? Are jellyfish really that deadly? We will find out!


Except the fact that jellyfish are no fish at all, they are invertebrate animals of the phylum Cnidari. Other members of the Cnidari for instance are sea anemones and corals. Jellies consist of 90 to 95% of water and have no brain, blood or heart. In the figure below you will see the diagram of the anatomy of a jellyfish. Jellies are composed of three different layers. Just like us humans jellies have a skin, it's their first layer, the epidermis. Followed by the second layer which makes most of the gelatinous material. You might call it jelly, gels or scientifically as mesoglea. The third and last layer is the gastrodermis. Some of you might ask yourself now how jellies can interact with their surrounding and even perceive sensations. It's simple, their body has a nervous system so called nerve net. Don't laugh but their mouth is also their anus.

Fig.1 Diagram of a jellyfish Source

Jellies have one big cavity where all the digestive processes happen. In fact the digestion of jellyfish is very fast since they need to stay lightweight. They can absorb nutrients very quickly.
Because they are carnivores they feed of zooplankton, small fish, little crabs etc.
Most of the species have tentacles with cnidocytes , which they use for hunt and are important for todays article.

Jellyfish don't hunt humans or hurt them intentionally. Incidents happen accidentally when humans get in touch with their tentacles and only if these contain cnidocytes. Even if you are underwater and don't see any tentacles it doesn't mean they aren't present. The largest jellyfish, the lions mane jellyfish, has tentacles that reach up to 36.5 meters and are so fine you wont see them.

Painful cnidocytes

Now that we know a little more about jellies we can talk about their danger. As already mentioned their tentacles contain harmful cells, so called cnidocytes. They use these for hunting or defending against other predators.

Fig.2 Nematocysts of a sea wasp Source

When a human gets in touch with their tentacles these cells adhere on the human skin. The figure below illustrates how the discharge mechanism works. The cnidocil acts as a trigger. If this trigger is activated, chemically or mechanically, the nematocyst is ejected and will penetrate the skin. In the picture number 2 we see the nematocysts of the sea wasp, one of the most deadly animal on our planet. It's an species of the box jellyfish. Causing terrible pain it can even lead to death within minutes if no medical help is provided immediately. The toxin can stop the heart beat and cause respiratory paralysis.

Fig.3 Discharge mechanism of Nematocysts Source

What to do?

  • Try to get out of the water as fast as possible. The next step should be to pour salt water over the area. It's is very important to not use fresh water. Since cnidocils act upon chemical changes the freshwater will make even more of the cells inject their venom into your body!
  • If you have accesses to vinegar use it instead. It will prevent the nematocysts to pop up and inject toxin into you. After that try to remove the needles with a tweezer. Don't use your hands!
  • If you don't have a tweezer use sand. Moisten your skin with water and put sand on it. Now try to wipe off the needles on your skin. Don't use your towel. It will make it worse!
  • Call for medical help and wait for rescue

The local citizen was right and these bottles were to help people that are stung by jellies.

Myth or Fact? #26 - Lightning can strike from ground upwards
Myth or Fact? #25 - Bats are blind
Myth or Fact? #24 – Watermelon Seeds will grow inside your Stomach
Myth or Fact? #23 – Tea has Theine and Coffee has Caffeine
Myth or Fact? #22 - You have to wait an hour to swim after eating
Myth or Fact? #21 - Stretching before exercise is dangerous
Myth or Fact? #20 – A Penny dropped off the Empire State Building kills you
Myth or Fact? #19 – Cold weather makes you catch a cold
Myth or Fact? #18 – Hair and nails keep growing after death
Myth or Fact? #17 – Cockroaches can survive a nuclear catastrophe
Myth or Fact? #16 – Skin on heated milk is dangerous
Myth or Fact? #15 - Survive a falling elevator by jumping up as it hits the floor
Myth or Fact? #14 - Mosquitoes prefer people with sweet blood
Myth or Fact? #13 - Does Santa Claus exist? 🎅
Myth or Fact? #12 - Acid and Base saves Life
Myth or Fact? #11 – Glass is a liquid
Myth or Fact? #10 – During summer the Eiffel Tower is taller
Myth or Fact? #9 - Hot water freezes faster than cold water
Myth or Fact? #8 - Oxygen runs out in overfilled rooms
Myth or Fact? #7 – Does a mirror swap left and right?
Myth or Fact? #6 – Radioactive contaminated waste glows green
Myth or Fact? #5 – Does drinking distilled water kill you?
Myth or Fact? #4 - We only use 10% of our Brain
Myth or Fact? #3 - Is it colder during Winter because the Sun is further?
Myth or Fact? #2- The world's most famous equation: E=mc²
Myth or Fact? #1 - The Five Second Rule

Thanks for reading this episode of Myth or Fact! If you enjoyed it feel free to resteem and leave a comment! I would love to know what you think about jellyfish!

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There is a horrifying scene in the movie Sphere (minor spoilers) wherein Queen Latifah is attacked and killed by a pack of jellyfish. Now that I've typed that out, it feels like I made it up.



It depends a lot on the specie of jellyfishes, and if I'm not wrong usually the big ones are not dangerous but little ones can represent a serious risk. Of course depends and it's not a rule.
I remember also a movie scene (don't want to spoiler the title) in which the main character use them to end his life.
Thanks for all the work Tim! Still waiting for bloodsucking bats article :P

Something too cruel way. How to jump into boiling water.

Thansk for the work Tim. Jellyfishes seems nice. great articles. Kindly follow me @bewajijohnson

Jellyfish were waiting for a long time to strike back... we have been eating their kind for a loooong time now.

Haha! Too funny!

Fact. Anything can really kill you, even paper.

I agree.

Danger is all around us!


They might kill you, but you know what else could do that in the future? Robots!! Take a look at robots of the future at Boston Dynamics DARPA funded company.

Check here some insane robot videos:

There is a horrifying scene in the movie Sphere (minor spoilers) wherein Queen Latifah is attacked and killed by a pack of jellyfish. Now that I've typed that out, it feels like I made it up.



Depends which one but most of them hurt like a pain in the A**

^^THE FLORIDA KEYS^^...So many jellies

Followed/upvoted/appreciated! I've seen some cool discovery channel stuff on jellyfish, but this goes much farther into explaining them! Nice post!!

They totally go under that " looks can be decieving" category!!!.. They look so pretty you want to touch them but it feels touching them to risk ur life would be a pretty darm dumb decision :]

Excellent post Tim!

I will summarize this post: YES @ironshield

amazing post great research dear @timsaid as you ever made.

Thank you!

Interesting question and analysis. Jellyfish can truly paralyze people. As beautiful as they are, they are dangerous like stingrays.

Another great post @timsaid !


Thanks for another fun post. I already knew that jellyfish can hurt like hell, but I did not know there are actual kinds that can paralyze or even kill you.

Be careful out there

Never been that keen on them, used to sea them all time when younger....

My old lady got stung by one in morocco once and it look nasty, she was saying it was sore as, didn't help the waiter was shouting 'glace' which sounded like 'glass' so I was running about looking for a fucking glass when 'glace' actually means 'ice'

Guess he was wrong on anyway lol took her to the docs, all was sorted

Was a good read, some interesting facts iv'e learned

I learn something new all the time, thanks to @timsaid! Jellyfish stings do hurt due to personal experience.

Ouch! And thanks :)

  ·  2 years ago (edited)

One of the tiniest and deadly venomous jellyfish is the Irukandji Jellyfish...

Time to urinate ;).. or at least thats for the sting.. or was that starfish?

''Smash that like button, let's get 500k likes or I'll kill my dog'' - every Youtuber ever belike

I guess your dog is toast !

Not particularly. It's the sea wasp, a species of the box jellyfish. There are some box jellies that are peaceful

That's true, the Box Jellyfish native to the Northern Australian coastline are lethal though.

  ·  2 years ago (edited)

I think if the jellyfish can kill humans is real, because jellyfish including a very poisonous sea animals.

That's a very good post @timsaid

Wow Awesome Post :D
But dont forget to upvote my blog too :D

Great post. I was stung by a jellyfish once as a kid. I had no idea what happened. I thought I must have scraped across a rock or something (but of course there was no rock to scrape against).

Wow that's hella crazy...glad I read this before I plan a trip to the ocean 😎. I've heard there even micro jellies that are way more toxic, do you know if this is true or myth??

I presume if you get swarmed by hounded jellyfish and get stinged wat away from the shores, yoy might die eventually.. But that stands to be proven.. I haven't heard of people dying from jellyfish.. Well personally the poisonous ones mogjt kill you..

I'm scared as hell of Jellies!!
Loved reading this! And will now upvote and resteem!
Thankyou and god bless haha

One of the best post i did read on steemit , ive been to thailand 2 month ago and i heard of them and i know how dangerous some jellyfish can be, people need to be more aware of them.

I will post about thailand alot if you want to see my post you can follow me

Have a good day and thank you again

I think some jellyfish don't sting? Or maybe their sting is very weak, because I remember when we were young we would catch these at Rehoboth Beach, VA and put them in buckets and play with them. Jellyfish and sandcrabs. It was a lot of fun! :)

It is true, not all have these needles with toxin. But some species do

Thank you for myths and fact.

Following - will wait for a next one

I love this Myth or Fact -series you do, always both educational and entertaining :)

another great and acknowledged post @timsaid .
keep it up.
upvoted and comment , Do the same .

Intersted science... Very nice ever I vote...
Good post @timsaid
Stay uptodate your post.

The ones that'll kill a human are called box jellyfish, and you can forget your vinegar if one gets you!

And on Australian beaches, if you're stung by the more common "blue bottle" jellyfish for instance, you don't need vinegar handy, you just get your mate (or a random stranger) to pee on it. No, seriously, urine will help sooth the sting... unless it's from box jelly, then your a goner, but they're only common in the northern tropical waters of Australia, where you've got other BIG things to worry about, like saltwater crocodiles! Now there's a man eater!

I have the feeling that in Australia everything will kill you lol

Hahaha. Yeah, snakes, spiders, crocs, sharks, poisonous fish, jellyfish, octopuses... a kangaroo can even kill a man... plus the cute and cuddly koala population have chlamydia which you can catch...

Nice going @azurejasper. Distract me mid comment to feed the baby, and steel my pee on the victim comment while sitting on the dunny.
Well I did a little research and it's not recommended.
I have posted some useful evidence based advice regarding the Chironex fleckeri commonly known as the Boxjelly.
Here's a fun fact too lol. My phone keeps spell correcting boxjelly to bachelor. 😂 I'm not kidding.
😘 love you x

wow i did not know this one thank you

Great post . Check out my profile if you have time :)

  ·  2 years ago (edited)

@timsaid well i cant say dt jelly fish can kill or not but i definetly know st peanut butter nd jelly can revive ur soul

@timsaid wow dude u upvoted me now m thinking how much would ur 100% vote will be lets give it a try throw a 100% vote here
#upvote100%tim ✌

Great article. Ive luckily never been stung but seen these critters many times in the sea in various places. You just need to steer clear but its not always that easy.

yes they can ...

Thanks for the tips! A friend of mine told me he had a jellyfish stuck to his leg one day after entering water and they ended up burning it off with a cigarette. Wasn't there but I always remembered that story!

Sounds painful!

yuzz that's what he said! Like a heavy burning sensation! Iek!

You can also reduce the pain and separate by jellyfish from your skin by urinating on it. It's disgusting, but actually does work.


They are particulary disgusting creatures for me so as soon as I spot one I'm running far away!

Wow, thank you for posting, this is very useful information!

@@ -114,17 +114,17 @@
l leaves

the body

@timsaid , wayback in my childhood days in our province were very near the sea and there are days that theres so many jellyfish in it, we tried to capture them using a net and one time unfortunately my skin collide on it and its very itchy and hot. Now I know that it is dangerous so I will talk to my aunt and tell her kids about it. Thanks for sharing.

Great article explaining jellyfish! They are such mysterious creatures that so few people understand. My favorite part was "jellyfish are no fish at all" lol keep up the great work!

haha :P


  ·  2 years ago (edited)

So, you get paralyzed in the middle of the ocean, you drown. No they don't kill people but yes, a jellyfish just killed a person....

I got wounded once by this creature, uforogettable experience... Good post, keep it up.

I can imagine. Glad you are here and can write.

Yes it can
Its most poisnes specie

I learned something new today :)

The ones we have here aren't deadly but it is said it hurts a lot, I see someone said peeing on the sting will alleviate the pain, I know that works with sea urchin stings I don't know about jelly fish.
And by the way did you know they are edible? Here in the Mosquitia coast there is a whole industry, they are dried and then exported to Asia, now I can't even imagine how many of these it would take to make a pound.

Thanks for the information. I wonder how much is left of the jelly after drying them since they are almost out of water lol

I remember when I was little I was in the water and I felt something touching my back. I thought it was my cousin. After a while I turned around and saw a jellyfish. I was very scared and I saved myself as soon as possible and then hundreds of jellyfish appeared in the water. Fortunately she had not stung me. It was in Brittany. In any case thank you for your advice which will be very useful for all those who will bathe this summer. I will follow you because your blog is interesting and I love science

Interesting post. I always try to stay out of their way for sure.

-:) interesting thoughts

Love scientific content, great article! I have just started out on steemit and do similar content to you. Would be grateful if you and other people checked my profile out!

Great post! @timsaid I'm learning alot from you. Thanks for sharing.

I see that you can now get pet jellyfish at the pet store now. Now only if I had a big enough tank to get my own Portuguese Man o War. They are like puppies with 50 foot long legs

Very informative and I learn something new.

Great content @timsaid, enjoyed reading your article and educating my brain . Upvoted (:

I think the Portuguese Man of War can kill people

Thanks. So informative

Wonderful, the ocean is as incredible as dangerous, in my opinion jellyfish, like other marine animals can cause death, but if you follow prevention recommendations we can save lives.

It's important to know that

Really good information, I had no idea to use sand to try to remove it and not fresh water. Thanks for sharing, living in Florida I've never been stung by a jellyfish, but it's never to late for it to happen

So, pee on your friend when he gets attacked!!
He'll thank you later.

  ·  2 years ago (edited)

Pee on your friend and he will attack you lol

Great post, Jellyfish are so cool, but deadly! I will have to remember this when i'm in Thailand in August.

Nice post and good to know that vinegar can help.

Follow me please.. Thankyou!

Much work,power and passion on your post's. Great stuff.
Tim said......and i listen ;)
Steem ON!!!

Jellyfish - they are like that!

Dangerous indeed...Some people say to use human urine to in case of emergency... Seems to be effective...

Yes the box jellyfish can, easily.

It's funny, the first thing that popped into my mind when I saw jellyfish was the time I loaded up on LSD at my friend James' house and I saw jellyfish coming out of his carpet and out of a painting on the wall.

I also apparently thought I was a T-Rex because I went stomping barefoot and half-dressed outside in the snow and almost lost a toe to frostbite. Also it was 3am so the pterodactyl screams I was making woke up my whiny ass neighbors. (I wish I could say all of that was a joke!)

Hey family check me post out :) it would mean the world to me <3

Congratulations @timsaid!
Your post was mentioned in my hit parade in the following category:

  • Upvotes - Ranked 8 with 496 upvotes

Some jellyfish are very tasty.

Sesame Jellyfish Salad Recepie:

  • Rinse and drain jellyfish; place into a bowl.
  • Whisk sesame oil, soy sauce, vinegar, sugar, chili oil, and ginger together in a small bowl; stir into jellyfish and marinate 15 minutes.
  • Place sesame seeds in a dry skillet over medium-low heat; toast until golden, about 1 minute. Set aside to cool, about 5 minutes.
  • Stir cilantro and green onions into jellyfish mixture; sprinkle with sesame seeds and serve immediately.

Here's another image.

killing people...I not sure....but it's dangerous creature....

It really depend on the type of jellyfish. Got stung twice and I'm still alive :) First on the legs, second between my nose and lip. T'was crazy! But I know someone who got stung on her body and it left an intense scar and caused her to be hospitalized for more than a week.

hellllllooooo @timsaid

nice post really i always ask myself about biology
i will belooking forward for other post
@loooping feel free to follow and up vote i will aswell do the same


Some species are indeed very dangerous. One interesting thing is that they dont have brains ,lucky indeed.

If peanuts can... ;)

Follow me for the latest in tech news from my paid subscriptions to Barrons, the Wall Street Journal and many more..

Scary creatures aren't they - they just fight back - the nature fights back. Have a great day @timsaid

I might be childish but I had a laugh about the mouth/anus situation here :D

They eat small fish and crabs ? Really ?
I had no idea!

I have seen a pic of the Lion's Mane Jellyfish!


That looks deadly!
These are such beautiful creatures but so deadly!
Not to mention scary!

Thank you for the post!
I didn't know Vinegar helped!

Upvoted and Followed! :)

  ·  2 years ago (edited)

Interesting post never knew of the box jellyfish. The Portuguese Man O War is the deadly one that can be seen in the Tropics. Curacao one past the scuba boat we were on. Nasty looking creature. Jellyfish Lake is famous for snorkeling with Jelly Fish -

Good info. Great articles.

I was stung by a man-o-war as a child and let me tell you...I certainly THOUGHT I was going to die!

I'm from the Philippines and this is also common especially during summer time (march-june). Years ago our neighbor's daughter died because of jellyfish sting. The marks were visibly squiggled all over her arms and legs. If you don't have vinegar, folk knowledge says you can use urine on the affected area.

I think I'll just stay out the water 🏖

  ·  2 years ago Reveal Comment

thank you for sharing

why is this even important? I never saw a jellyfish.

I'd say yes, because almost anything can kill a person if their immune system can't handle "whatever"...

I have been Stung by a jellyfish and I am still here but maybe if thousands stung you at once then maybe you might die anyway good Article thank you for the info.

Living in Australia, swimming into blue bottles is fairly common. A few years back I swam into a massive group of them and at first was afraid I was going to die, then after the pain set in I was afraid I wasnt going to die! haha seriously though... wise to stay clear... they defend their territory professionally.