Can jellyfish sting outside of water?

Can jellyfish sting outside of water?

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According to my understanding of the Wikipedia page on the stinging cells of the jellyfish, the mechanism of delivering the toxic missile is largely due to water pressure. Does that mean that a jellyfish on land (or brought out water) is unable to, or perhaps less efficient at, delivering its stings?

Short answer
Jelly fish can sting out of the water and even when they are considered to be dead.

I do not have detailed scientific literature available. However, popular sources generally and equivocally warn against touching jelly fish, even on land and even when they appear to be dead. In fact, dead box jelly fish can be as dangerous as live ones (ABC News).

Credible sources
- National Poison Control Center
- UK Telegraph
- ABC News

These jellyfish can sting without touching you, thanks to 'mucus grenades'

Cassiopea jellyfish make up for their lack of tentacles by releasing gooey clouds full of autopiloted stingers.

Swim through the mangrove forest waters of the world, from the coasts of Florida to Micronesia, and you may encounter a jellyfish that stings despite having no tentacles. In fact, you needn’t even touch these jellies to get zapped.

How is that possible? According to a study published Thursday in Communications Biology, the spicy trick relies on clouds of mucus teeming with microscopic venom “grenades.”

These so-called upside-down jellyfish, named for the way they spend their lives belly-up on the ocean floor, have been the subject of study for more than a century. But no one had quite figured out how the jellies’ goo worked until now. Doing so can help explain why these jellies so often harm swimmers, even from a distance.

“We knew it had to be something in the mucus,” says Cheryl Ames, a marine biologist at the Smithsonian National Museum of Natural History and a co-lead author of the new study.

Upside-down jellyfish of the genus Cassiopea produce tons of sticky mucus that trap small prey, such as brine shrimp, almost like a spider’s web. Some fish even perish in the slime. What’s more, when human divers swim near the jellies, they can experience what’s known as “stinging water sensation” anywhere skin is exposed, despite never coming into contact with the invertebrates. The sensation is typically described as an annoying itch or burn, but laboratory tests on the venom suggest that excessive exposure could be detrimental.

When Ames and her colleagues looked at the mucus under a microscope at high magnification, they discovered something swimming inside the slime.

They were autonomous, moving around like little Roomba vacuums.

The scientists call the newly-described structures cassiosomes, but you can think of them as microscopic pieces of popcorn. Each grenade is made of a jelly-filled center, a number of stinging cells, called nematocysts, and 60 to 100 hair-like cilia that allow the cassiosomes to paddle through the muck.

“They were autonomous,” Ames says, “moving around like little Roomba vacuums and bumping into the brine shrimp that we fed them, just killing them on contact, and moving on to the next.”

Some Jellyfish Are 98 Percent Water

The main body of a jellyfish—its bell—is made of two thin layers of cells with non-living, watery material in between, says jellyfish biologist Lucas Brotz, a postdoctoral research fellow at the University of British Columbia in Vancouver.

This simple structure is a “neat evolutionary trick,” he says, that lets them grow big and eat more things without the cost of a high metabolism.

“They’ve survived every mass extinction,” Brotz says. While most species that ever lived have gone extinct, “this group of bags of water that have somehow survived,” for over 600 million years.

Can Jellyfish Live Out of Water?

Jellyfish do not have enough adaptations to live outside of water. In order to do this they would need an excretory system for the osmoregulation and a true ambulacral system. Jellyfish typically only live for about a year and if they do not live for about a year it is most likely because they were eaten by a fish, turtle, bird or something like that. Another way they can die early is if they are not in salt water. Jellyfish need saltwater in order to stay alive.

When a jellyfish gets washed up to shore it cannot get back into the water. If you spot one lying on the beach you should never touch it as it can still sting you, even if it appears to be dead or actually is dead. Something that is rather interesting though is that when jellyfish wash ashore, they melt. All that will be left is some of its skin.


That was a great answer and I proved my sister wrong so that pretty good

I first saw a washed up jellyfish from an episode of a Korean Show called Running man and so I was really confused because not only did it look gross (to be very honest, they look better in water) but like this web says, i knew they were mostly made out of water. Reading this, i felt like i learned something new, because, even though it all makes sense, i certainly didn’t know that they would melt if they were out of their habitat. Thanks!

I fought a Jellyfish when I went to the beach, I took it out of the water and into the shore for like 5 minutes. Then I took it back to the water and it still seem to be alive, it was moving it’s body.
I touched it for like 5 seconds it’s top part and it was really hard, I was expecting it to be squishy/wavy.
(btw I caught it in a fishing bag made of thin rope)

I meant caught not fought lol my bad.

It helped me a lot at first I thought they can live on water but after seeing this answer I got it.

This is how jellyfish can sting you without even touching you

Most people know not to poke a jellyfish, but some jellies can sting you without touching you – by detaching tiny bits of their body that float off into the sea and move around independently.

Upside-down jellyfish jettison small balls of stinging cells in a network of sticky mucus, to kill prey such as shrimp. The jellies then seem to suck in their dinner by pulsating.

It is as if we could spit out our teeth and they killed things for us somehow, says Cheryl Ames at Tohoku University in Japan. “It’s a real evolutionary novelty.”


Upside-down jellyfish, several species of the genus Cassiopea, live in warm coastal waters such as off Florida, Australia, the Red Sea and southerly parts of the Mediterranean. Their sting isn’t generally seen as dangerous, but there have been occasional reports of “stinging water” in their vicinity.

“It’s really irritating, you’re constantly being pricked on any surface that’s exposed,” says Ames.

Read more: Jellyfish as you’ve never seen them – meet the underwater aliens

Now Ames’s group has found that this happens because the creatures shed hollow balls of stinging cells up to half a millimetre wide. Dubbed cassiosomes, they carry hairs that can waft them around in circles to boost their chances of bumping into prey.

“It was a really amazing moment when we all took turns looking through the microscope and saw there were tiny little things moving about in the mucus,” says Ames.

The jellies released cassiosomes and mucus when brine shrimp, their natural prey, were put in their tank. The cassiosomes killed the shrimp in under a minute, as shown in the video below.

In the wild, the dead shrimp are then sucked into the jellies’ feeding pores by their pulsating motions.

These jellies tend to float at the bottom of coastal lagoons, and extend their networks of mucus to float above them. The mucus may not be easily visible to swimmers, says Ames.

The unique feeding mechanism isn’t the jellies’ main source of nutrition. They also have algae inside them, which photosynthesise. The reason the jellies float upside down is to expose these plant cells to the sun.

The cassiosomes also contain algae, which might provide their energy for wafting around – they survive outside the jellies for up to 10 days in the lab.

Journal reference: Communications Biology, DOI: 10.1038/s42003-020-0777-8


The word ‘jellyfish’ is used to describe a range of species, many of these are related to true jellyfish, but comb jellies are not closely related at all and do not sting. Instead they use sticky tentacles to catch their prey. Close relatives of true jellyfish include the sometimes deadly box jellyfish and the Portuguese Man O’War. There are thirty six different species of Box jellyfish they have twenty four eyes, are able to detect colour and can swim as fast as an Olympic swimmer! The Portuguese Man O’War is commonly mistaken for a jellyfish but it is colony of animals called siphonophores each individual has a specific role to play in the colony, including one which acts as the large float.

Amazing Facts

  • A group of jellyfish is called a ‘smack’ although it is more commonly referred to as a ‘bloom’.
  • Jellyfish have no eyes but can sense light, they don’t have a sense of smell, a brain or a skeleton.
  • Although jellyfish tentacles are covered in poisonous stinging cells, some young fish hide among them for protection
  • Jellyfish are an important food for humans and catches are increasing. They are usually preserved by drying and are considered a delicacy in some parts of Asia

Fun Facts about the Jellyfish!

Jellyfish are one of the oldest animals on Earth and have changed very little from their prehistoric ancestors. These fascinating creatures have been studied by scientists for decades, increasing our understanding of the biological adaptations that have enabled them to persist in the world’s oceans for so long. Let’s take a closer look!

Jellyfish Sting

Jellyfish are known for their sting! These animals have tentacles that have tiny sting cells on them called cnidocytes. These cells have tiny structures inside them that are full of venom, called nematocysts. When something touches a jellyfish these nematocysts shoot out and can penetrate the skin of the animal. The jellies use this mechanism to help capture prey or as a defense mechanism when they feel threatened.

Like most venomous animals, the jellyfish inject their venom to cause pain and irritation. Jellyfish venom contains a type of protein called a porin which is responsible for the pain caused by their sting. This protein is not only found in the venom of all jellyfish but also in their relatives, including corals and anemones.

Humans can also be stung by jellyfish which can result in mild symptoms such as pain and blistering, to more serious symptoms including whole-body illness. In some cases, stings can even be life-threatening.


Many jellyfish species have the ability to produce their own light, in a process known as bioluminescence. This light is used primarily as a form of communication between animals and can be used for defense, offense, and intraspecific communication. The greatest diversity in jellyfish bioluminescence occurs in deeper water, where nearly every kind of jellyfish is luminescent and is mostly used in defense against predators.

The light is produced by a chemical reaction between a chemical substance called luciferin and oxygen from the environment. This reaction releases energy and as a result, light is emitted. An enzyme called luciferase helps this reaction occur. For an animal to emit light regularly they must continually bring new luciferin into their system. Some animals acquire it through their diet while others can produce their own.

Bioluminescence is found in many marine organisms including around 1500 species of fish! Some species of sea stars, crustaceans, worms, and sharks are also luminescent.

Jellyfish in Space

Jellyfish are so cool they have even traveled into space! In 1991, some moon jellyfish were sent into outer space on board the Space Shuttle Columbia. This mission was a study conducted by scientists to understand how microgravity affected them.

While in space, the number of jellyfish multiplied. On their return to Earth, the scientists examined these space-born animals and discovered that unlike Earth-born jellies, they couldn’t figure out how to deal with gravity.

Scientists have sent a number of animals into space including monkeys, dogs, ants, cats, frogs, and fruit flies!

Vinegar can be used to Neutralise Jellyfish’s Sting?

KUALA LUMPUR: “One moment you are laughing and playing in the water and the next, you are maybe screaming in agony as your legs suddenly feel as if these are on fire.

“Actually, you’ve just been stung by a jellyfish,” explained a veteran scuba diver Steven Martyn when met at a hospital here.

What should the victim do?

Martyn said there are several measures that a victim of jellyfish sting can do and the first very important aspect is not to panic.


He said once stung, the first impulse of the victim is to immediately start wiping away the jellyfish’s tentacles and rub the affected area.

“This may only trigger unfired nematocysts attached to the skin and inject more venom,” said Martyn.

According to a recent eMedicine article on the Internet, the venom of many jellyfish species is complex and largely unknown.

Medical experts say a jellyfish sting can elicit one of three types of responses to the injected toxin.

“An immediate allergic reaction, a delayed allergic reaction, or a toxic reaction,” they say.


Martyn, who has a Master’s in Marine Biology, said first responders to a jellyfish sting victim should first protect themselves and the victim from further injury by inactivating the remaining nematocysts.

This can be accomplished by using a 4-6 per cent solution of acetic acid or household vinegar for a minimum of 30 seconds.

“Soaking for 30 minutes is recommended. Alternative solutions can be Coca-cola, old wine, or hot water.

“Do not use alcohol, liquor, urine or fresh water as claimed by some parties,” he said.

Once the nematocysts have been inactivated with vinegar, the attached tentacles can be removed.

“It is best to remove the tentacles with tweezers as live nematocysts can sting through surgical gloves,” Martyn said, issuing a word of caution.

Check for signs of anaphylaxis such as difficulty in breathing and swallowing, swelling, or severe pain, and seek immediate medical attention.

Stings by the box jellyfish species are very painful and anti-venom injection may be required.

According to the medical fraternity, pain management will be a top priority with jellyfish sting victims.

Toxins can kill localized skin cells and can release systemic toxins.

Experts say victims will want relief from both.

“Using a cold compress over the sting area will help in many cases while a hot pack may help with severe pain,” they say.

According to eMedicine, “Topical anesthetics and corticosteroids may also relieve pain.”

Systemic body pains that are caused by the toxins can be treated with painkillers acetaminophen and Ibuprofen. Anti-histamines may also prove useful.

Wounds caused by stings should be monitored for several weeks to check for infections or delayed allergic reaction. Localized skin damage and scarring may occur.

Most diving safety organizations recommend vinegar as immediate first aide for a jellyfish sting.

Vinegar, which neutralizes a jellyfish’s stinging cells, has two primary benefits – to minimize pain and discomfort, and to stop the delivery of jellyfish venom.

Martyn said when stung by a jellyfish with exceptionally toxic venom, such as a Box Jellyfish, the immediate application of vinegar to neutralize stinging cells and prevent more venom from entering a diver’s body may be the difference between life and death.

He also said vinegar should be in every dive boat’s first aid kit.

“If vinegar is not available, a paste of baking soda may be used to neutralize sting cells. Salt water may be used as an additional rinsing agent if necessary.

“In no circumstances should fresh water be applied to a jellyfish sting as fresh water may cause additional stinging cells to fire,” he said.

According to Martyn, urinating on jellyfish stings is not recommended to neutralize the jellyfish venom.

Doctors recommend hydrocortisone cream to be applied topically to the stung area.

They say the victim of a jellyfish sting should be monitored carefully for signs of shock, difficulty in breathing, nausea, and other signs of severe allergic reactions.

If any allergic reaction is suspected, be sure to contact a doctor immediately. – BERNAMA

These Jellyfish Don’t Need Tentacles to Deliver a Toxic Sting

A mysterious burning, itchy sensation after a swim is usually the telltale sign of a jellyfish sting.

But in coastal mangroves and other subtropical ecosystems, snorklers and swimmers have long reported a similar sensation without ever coming in contact with a jellyfish. A phenomenon called “stinging water” is to blame, but the cause is unknown.

One potential culprit is a type of jellyfish belonging to the genus Cassiopea called the upside-down jellyfish, but they are missing a key appendage normally necessary to deal a stinging blow: spaghetti-like tentacles.

Instead of a gelatinous, umbrella-shaped body with long, swaying tentacles undulating beneath as it floats through the water, Cassiopea got its common name for being the exact opposite. The soft, circular body, known as the medusa, rests on the seafloor while just a few short, tentacles float above them. Cassiopea are known to get the bulk of their energy through their symbiotic relationship with the photosynthetic algae Symbiodinium that lives within their body.

But how could the upside-down jellyfish sting something without ever coming in direct contact with their victims? These unassuming invertebrates are known to unleash plumes of mucus into the water, and though the slime was certainly a suspected cause of the irritation, scientists had never researched what elements of the slime might lead to pain before.

In a paper published today in Nature Communications Biology, researchers found that the mucus is laced with toxic bubble-like tissues covered in the same stinging cells that cause the iconic jellyfish itch.

Study coauthor Allen Collins, a NOAA invertebrate zoologist, is no stranger to this stinging sensation. While completing field work at the Smithsonian Tropical Research Institute in Panama, Collins fell victim to the so-called “stinging water” while handling the upside-down jellyfish.

“I picked up quite a bunch of them and brought them back to the lab,” Collins says. “Even though I had gloves on I was very soon uncomfortable where my skin was exposed, around my neck and my face.”

Collins has long shared his experience as a cautionary tale for students when introducing them to upside-down jellyfishes reared in the Department of Invertebrate Zoology at Smithsonian’s National Museum of Natural History. One of those students is first author of the study Cheryl Ames, now a marine biologist at Tohoku University in Japan who started this research while she was a Ph.D. researcher working with Collins at Smithsonian’s National Museum of Natural History.

Ames and several other researchers decided to view at the mucus under a microscope when they couldn’t find the stinging sensation associated with the slime in scientific literature. Upon closer look, they found that the plumes expelled by the upside-down jellyfish are loaded with tiny spheres encased in nematocysts, which are the same stinging cells jellyfish are traditionally known for.

“They’re roughly ovular, shaped like asteroids with little bumps on them,” Collins describes. “And on those bumps are where the stinging capsules are concentrated.”

The oval structures along the protruding edges are stinging capsules known as nematocysts, and the brown cells in the interior are symbiotic algae that live within the tissues of Cassiopea. (Cheryl Ames, Anna Klompen)

Dubbed cassiosomes by the team, the capsules are covered in fine, hair-like structures known as cilia. The cilia allow the entire cassiosome to gyrate and spiral within the mucus. In a laboratory experiment, researchers found that the cassiosomes are capable of incapacitating brine shrimp, providing evidence that the jellyfish release cassiosomes to stun prey before eating them.

Cassiopea species have been known since 1775, and their mucus spewing behavior is well-described. At first, Collins thought for sure the research had already been done.

“I had always assumed that it was well explained somewhere in the literature and that we just hadn’t come across it yet,” Collins says. “When we started going into the literature, we didn’t find anything other than a couple brief asides. No one had worked this out in detail.”

The phenomenon of stinging water is not a new finding, but the discovery of the source is truly valuable, explains Leslie Babonis, a researcher at the Whitney Laboratory for Marine Bioscience.

“Think about how crazy this is – it’s energetically costly for animals to produce new cells and tissues and the upside-down jellies are just dumping huge masses of these things into the water column to deter passers-by,” says Babonis, who was not involved in this study.

This team of researchers have uncovered an entirely unknown mechanism of stings, as cassiosomes have since been found in other related jellyfish species and could be even more widespread.

Cassiopea, or upside-down jellyfish, on display at the National Aquarium. (National Aquarium)

Oddly enough, however, the team also found that the cassiosomes are hollow and filled with the same photosynthetic, symbiotic algae the live freely in their bodies. Because expelling mucus is so energetically costly, Collins speculates that the Symbiodinium could provide energy to the cassiosomes as well. In the lab, cassiosomes could survive in seawater for at least ten days. Why the mechanism exists remains unknown, but Collins hypothesizes about a few possibilities.

One could be that cassiosomes help to disperse Symbiodinium, which is beneficial both for the algae and the jellyfish. Cassiopea can take up the algae from the water, which is necessary for development.

"We know there's a really tight symbiosis there,” Collins says. “They can’t produce a medusa unless they have Symbiodinium in their tissues. Cassiosomes may be a way for the algae to get out and get around.”

Representation of a cassiosome, including its cross section. (Nick Bezio)

Understanding this symbiotic relationship certainly interest biologists, but explaining “stinging water” and better understanding how marine creatures produce and disperse venomous goo may have also have wide-ranging impacts for human health. Because Cassiopeia is already recognized as a model organism, meaning the species is used in laboratory studies to better understand biological processes, this study could lead to exciting new discoveries about other jellyfish species as well.

For now, the researchers—and probably a lot of snorkelers and swimmers—are happy the “stinging water” mystery has been solved.

Stinging water mystery solved: Jellyfish can sting swimmers, prey with 'mucus grenades'

Three Cassiopea, or upside-down jellyfish, from Bonaire, Dutch Caribbean seen from above in the lab at the Department of Invertebrate Zoology in the Smithsonian's National Museum of Natural History. The cloudy matter floating above and to the left of the jellyfish is a mucus that they exude. A team led by scientists at the Smithsonian, the University of Kansas and the U.S. Naval Research Laboratory report in the Feb. 13, 2020 issue of the journal Nature Communications Biology that they have discovered microscopic stinging structures inside the mucus secreted by upside-down jellyfish that cause swimmers and prey to be stung without coming into contact with these jellyfish. Credit: Allen Collins and Cheryl Ames

In warm coastal waters around the world, swimmers can often spot large groups of jellyfish pulsing rhythmically on the seafloor. Unless properly prepared with protective clothing, it is best to steer clear of areas that Cassiopea, or upside-down jellyfish inhabit: getting too close can lead to irritating stings, even without direct contact.

Now, researchers have taken a close look at the cause of the "stinging water" encountered near these placid-looking creatures: a toxin-filled mucus the jellyfish release into the water. In the Feb. 13 issue of the journal Nature Communications Biology, a team led by scientists at the Smithsonian's National Museum of Natural History, the University of Kansas and the U.S. Naval Research Laboratory reports on microscopic structures they have discovered inside the mucus—gyrating balls of stinging cells that they call cassiosomes.

"This discovery was both a surprise and a long-awaited resolution to the mystery of stinging water," said Cheryl Ames, museum research associate and associate professor at Tohoku University. "We can now let swimmers know that stinging water is caused by upside-down jellyfish, despite their general reputation as a mild stinger." The jellyfish is commonly found in calm, sheltered waters such as lagoons and mangrove forests.

The study, a multidisciplinary exploration of cassiosomes conducted over several years, grew out of the curiosity that Ames, National Oceanic and Atmospheric Administration (NOAA) zoologist Allen Collins and colleagues had about the discomfort they had all experienced firsthand after swimming near upside-down jellyfish. It began when Ames was a graduate student in the invertebrate zoology lab that Collins heads at the museum and culminated when Ames, as a postdoctoral fellow at the U.S. Naval Research Laboratory, investigated the question further as an issue of safety for scientists, the military and recreationists. Initially, Ames said, she and her colleagues were not even sure jellyfish were responsible for their stinging, itching skin, since several other ideas had been put forward about the phenomena, including severed jellyfish tentacles, "sea lice," anemones and other stinging marine animals. But they knew that the upside-jellyfish in the museum's aquarium-room lab tanks released clouds of mucus when they were agitated or feeding, and they wondered if they might find the culprit there.

A team led by scientists at the Smithsonian's National Museum of Natural History, the University of Kansas and the U.S. Naval Research Laboratory report in the Feb. 13, 2020 issue of the journal Nature Communications Biology that they have discovered microscopic stinging structures inside the mucus secreted by upside-down jellyfish--gyrating balls of stinging cells that they call cassiosomes. These cassiosomes can sting swimmers and prey without coming into contact with the jellyfish themselves.While its exact role in the ocean is not yet known, Ames said cassiosome-packed mucus may be an important part of upside-down jellyfishes' feeding strategy. While the photosynthetic algae that live inside upside-down jellyfish provide most of the animals' nutritional resources, the jellyfish likely need to supplement their diet when photosynthesis slows--and toxic mucus appears to keep incapacitated critters close at hand. Credit: Anna Klompen

When Ames and Smithsonian interns Kade Muffett and Mehr Kumar first placed a sample of the jellyfish mucus under a microscope, they were surprised to see bumpy little balls spinning and circulating in the slimy substance. Together with Anna Klompen, a graduate student at the University of Kansas and former museum and NOAA fellow, they turned to several more sophisticated imaging methods to examine the mysterious masses closely, and eventually a clearer picture emerged. The bumpy blobs, they discovered, were actually hollow spheres of cells, probably filled with the same jelly-like substance that gives jellyfish their structure. Most of the outer cells were stinging cells known as nematocytes. Other cells were present, too, including some with cilia—waving, hairlike filaments that propel the cassiosomes' movements. Puzzlingly, inside the jelly-filled center of each sphere was a bit of ochre-colored symbiotic algae—the same sort that lives inside the jellyfish itself.

Taking another look at the jellyfish themselves, the team was able to detect cassiosomes clustered into small spoon-like structures on the creatures' arms. When they gently provoked a jellyfish, they could see cassiosomes slowly break away, steadily leaving the appendages until thousands of them mingled with the animal's mucus. They also found that the cassiosomes were efficient killers of lab-fed brine shrimp, and videos that the team produced show tiny crustaceans succumbing quickly to the venomous spheres in the lab. Molecular analyses conducted at the museum and the U.S. Naval Research Laboratory identified three different toxins within the cassiosomes.

While its exact role in the ocean is not yet known, Ames said cassiosome-packed mucus may be an important part of upside-down jellyfishes' feeding strategy. While the photosynthetic algae that live inside upside-down jellyfish provide most of the animals' nutritional resources, the jellyfish likely need to supplement their diet when photosynthesis slows—and toxic mucus appears to keep incapacitated critters close at hand.

The oval structures along the protruding edges are stinging capsules known as nematocysts, and the brown cells in the interior are symbiotic algae that live within the tissues of Cassiopea, or upside-down jellyfish. Credit: Cheryl Ames and Anna Klompen

"Venoms in jellyfish are poorly understood in general, and this research takes our knowledge one step closer to exploring how jellyfish use their venom in interesting and novel ways," Klompen said.

Collins said the team's discovery was particularly exciting because Cassiopea jellyfish have been recognized for more than 200 years, but cassiosomes have remained unknown until now. "They're not the most venomous critters, but there is a human health impact," he said. "We knew that the water gets stingy, but no one had spent the time to figure out exactly how it happens." Already, the team has identified cassiosomes in four additional closely related jellyfish species, reared at the National Aquarium, and they are eager to learn whether they might be even more widespread.