What happens when someone is stung by a jellyfish?

What happens when someone is stung by a jellyfish?

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What happens in the human body when someone is stung by a jellyfish; namely a box jelly. Judging by what I have heard about the stings I'm guessing that they involve a neurotoxin.

But what is actually happening? What are the symptoms and what happens after the sting (treatments and survivability)?

The problem is that box jellyfish doesn't specify one jellyfish but a group of different jellyfish. Some of these are highly venomous - I pick here Chironex fleckeri, as this is often called "the most venomous jellyfish in the world".

Chironex fleckeri has long tentacles which are covered with millions of explosive cells called Cnidocytes which inject a dart with the very powerful toxin upon touch. It is therefore very dangerous to touch the tentacles with bare hands to remove them.

The toxin is a mix of different bioactive proteins which have cytolytic, cytotoxic, inflammatory or hemolytic activity. Case reports (you can find information in reference 3 about it) show that the tentacles "burn" though all skin layers causing immediate strong pain and lasting scars (if the victims survive) which tend to show signs of necrosis. The toxins itself paralyze the muscles of the heart and the respiration and also causes hypokalemia by hemolyzing red blood cells (one of the toxin acts as a membrane pore in the blood cells). This causes further problems and often a cardiac arrest. See reference 1 and 2 for details on the toxins. Especially 2 is interesting, as this is a PhD-Thesis on this topic with a lot of references.

Treatment depends on how severe the injury is - in severe cases an antivenom can be used. Besides this typical measures are CPR, giving oxygen and removing the tentacles (with appropriate protection). See reference 3 (good overview) to 5 for details on this topic.


  1. Chironex fleckeri (Box Jellyfish) Venom Proteins: Expansion of a Cnidarian Toxin Family that Elicits Variable Cytolytic and Cardiovascular Effects
  2. The molecular and biochemical characterisation of venom proteins from the box jellyfish, Chironex fleckeri
  3. Chironex fleckeri (Multi-tentacled Box Jellyfish)
  4. Jellyfish stings and their management: a review.
  5. Cytotoxic and cytolytic cnidarian venoms. A review on health implications and possible therapeutic applications.

The Best Way to Treat a Painful Jellyfish Sting, According to Doctors

Should you really pee on a jellyfish sting? We asked experts to weigh in.

If you&rsquove ever been stung by a jellyfish, you&rsquore definitely not alone. Last summer, The Weather Channel reported that more than 3,000 people were treated for jellyfish stings in Central Florida in just two weeks.

&ldquoVery rarely, you can have a systemic reaction to the sting, which requires immediate medical attention,&rdquo says Mark Conroy, M.D., an emergency medicine physician at The Ohio State University Wexner Medical Center.

Jellyfish stings are typically easy to treat, even though they can be pretty painful. But there are a lot of myths about what to do after one gets you: Should you wash it off and hope for the best? Grab some ice? Have someone pee on you? This isn&rsquot exactly something that&rsquos covered in-depth during high school science class.

So, before you hit the beach this summer, read up on exactly what you should (and shouldn&rsquot) do if a jellyfish stings you, according to doctors.

Scientists discover how jellyfish know when to sting

The starlet sea anemone uses specialized stinging cells to detect changes in its environment and fire a toxic barb to pierce and envenomate prey. The stinging cells in the tentacles use a unique ion channel to trigger stinging in response to prey. Credit: Christophe Dupre and Keiko Weir

To sting or not to sting? For jellyfish, that is the question whenever their tentacles brush up against anything, including millions of human swimmers around the world.

Stingers are fired out at about the speed of a discharged bullet. And each single specialized cell responsible for a response can only be deployed once, as they rupture when used and have to be grown back after a jellyfish ejects its venom-coated barb into an unsuspecting prey or an unlucky swimmer. Given the limitations on its arsenal, it would seem some prudence is in order.

"To prevent unnecessary stinging [including of itself], there must be some kind of signal that allows the cell to shoot at the right time," said Nicholas Bellono, assistant professor of molecular and cellular biology in the Faculty of Arts and Sciences. How that stinging trigger and safeguard system works on a molecular level in jellyfish and sea anemones has long been a mystery to scientists. At least, it was until a team of researchers from Bellono's lab solved it.

They identified how the stinging cells, called nematocytes, which are found along the tentacles of sea anemones and jellyfish—both types of cnidaria—detect and filter diverse cues from the environment to control when (and when not) to sting.

The researchers found that nematocyte cells from the starlet sea anemone, a relation of the jellyfish, have an unusual calcium electrical current that is critical for initiating the stinging response, but that the ion channel controlling this current only opens under very specific conditions: a combination of mechanical stimuli from a tentacle making contact with a prey or predator, like a poke, and the presence of certain chemical cues, like those from prey or predators.

The starlet sea anemone uses specialized stinging cells to detect changes in its environment and fire a toxic barb to pierce and envenomate prey. The stinging cells in the tentacles use a unique ion channel to trigger stinging in response to prey. Credit: Christophe Dupre and Keiko Weir

During all other times, these calcium channels are inactive and render the cell dormant until the right signal approaches.

"We hypothesize that first, the sea anemone detects chemicals from its prey using chemosensory cells," said Keiko Weir, a graduate research fellow who led the project. "These chemosensory cells then relay this information to nematocytes using acetylcholine [an organic chemical that acts as a neurotransmitter]. The acetylcholine relieves inactivation of these calcium channels. This functions to prime the nematocyte to say, "There's food nearby." Then, once the nematocyte receives a mechanical cue, such as the tentacle contacting prey, that leads to the opening of the calcium channels, resulting in a huge calcium influx and the discharge of the nematocyte."

Previous studies had already demonstrated that only the right combination of cues trigger nematocytes to fire, but the molecular process was unknown. The findings put it all together and highlight how nature has continuously developed elegant but simple systems for dealing with complex problems that call for ultrafast decision-making.

"The underlying principles of any biological system is you have cells that have to take cues from their surroundings—either from other cells or directly from the environment—and translate that information into an appropriate response," Weir said.

What makes this system stand out in particular is that the final say of whether to sting comes down to the nematocyte.

The upside-down jellyfish points its stinging cell-filled tentacles toward the water column to capture prey and deter predators. Credit: Lena van Giesen

"It's a great example of when a single cell has to properly integrate the right signals in order to make a correct (and very extreme) decision," Bellono said. "We're often thinking about systems-level questions in which the brain makes complex computations using several components of a circuit, but this study helps demonstrate that each protein and each cell is critical to such processing because it comes down to one molecule having just the right properties to fit its cellular and organismal context."

Along with Weir and Bellono, other co-authors included Christophe Dupre, a postdoctoral fellow from the Engert and Lichtman Lab Lena van Giesen, a postdoctoral fellow in the Bellono lab and Amy Lee, an assistant professor at Harvard Medical School. The study published in eLife in May.

The team used a variety of techniques, including physiology, behavior, and electron microscopy, that allowed them to meticulously follow the electrical and chemical processes leading to the stinging response.

As to why jellyfish sting an estimated 150 million people each year when humans are not its prey, the best answer is still likely a defense response. It could also lie in our chemical makeup, however.

"This comes back to which chemicals are sensed," Bellono said. "Is the animal adapted to very broadly sense some generalized chemical that's present in many animals such as us, even though we're not prey? There are examples of sea anemones which use specific nematocytes for predation and others for defense. There are other animals which may use chemicals to avoid stinging, such as the clownfish. Maybe those nematocytes are tuned to specific chemical inputs."

Ultra-soft underwater grippers use fettuccini-like fingers to catch and release jellyfish without harm

Along with Weir and Bellono, other co-authors included Christophe Dupre, a postdoctoral fellow from the Engert and Lichtman Lab Lena van Giesen, a postdoctoral fellow in the Bellono lab and Amy Lee, an assistant professor at Harvard Medical School. The study published in eLife in May.

The team used a variety of techniques, including physiology, behavior, and electron microscopy, that allowed them to meticulously follow the electrical and chemical processes leading to the stinging response.

As to why jellyfish sting an estimated 150 million people each year when humans are not its prey, the best answer is still likely a defense response. It could also lie in our chemical makeup, however.

“This comes back to which chemicals are sensed,” Bellono said. “Is the animal adapted to very broadly sense some generalized chemical that’s present in many animals such as us, even though we’re not prey? There are examples of sea anemones which use specific nematocytes for predation and others for defense. There are other animals which may use chemicals to avoid stinging, such as the clownfish. Maybe those nematocytes are tuned to specific chemical inputs.”

This research was supported by the New York Stem Cell Foundation, the Searle Scholars Program, the Sloan Foundation, the Klingenstein-Simons Fellowship, the National Institutes of Health, and the Swiss National Science Foundation.

Jellyfish sting treatment

It can be hard to know which species of jellyfish has stung you. Treat any sting as if it is a sting by a major box jellyfish or other box jellyfish if:

  • it is in the tropics in Australia
  • you aren't sure what the jellyfish is
  • there are multiple sting sites
  • the person stung seems unwell

Major box jellyfish

Call triple zero (000) for an ambulance and start the following first aid:

  • Put plenty of vinegar on the jellyfish stings. This stops any nematocytes that haven't already fired venom from firing. If vinegar is not available, wash with sea water.
  • Carefully remove the tentacles from the skin.
  • If the person is unconscious, perform cardiopulmonary resuscitation (CPR)

Other box jellyfish

If Irukandji-like symptoms occur (as described above), call triple zero (000) for an ambulance then:

  • Put plenty of vinegar on the jellyfish stings.
  • Carefully remove the tentacles from the skin.

Bluebottle and minor jellyfish

  • Wash the sting site with sea water and remove any tentacles.
  • Immerse the sting or run hot water on the skin for 20 minutes. Make sure the hot water will not burn the person. It should be as hot as they can tolerate &mdash around 45 degrees Celsius. The person can also have a hot shower.
  • If there is no hot water, an ice pack may help to relieve the pain.

Vinegar should not be used for bluebottle stings since it doesn't help the sting and may increase the person's pain.

As you can see from the photos, jellyfish stings usually appear as raised welts. The marks are often in the form of squiggly lines from their tentacles. It’s like free-form art.

The burn-like marks on the photo (left) are likely due to the tentacles being stuck to the skin for a long period of time, or, as the skin heals it may become scab-like and turn a darker color.

The photo on the right shows a typical, non-serious sting that will be painful for a few hours and subside.

Here’s What Happens When You Get Stung By a Box Jellyfish

Most jellyfish drift aimlessly with the ocean’s current these jellyfish hunt. Most jellies are brainless lumps of primitive goop these ones have a brain and over 20 all-seeing eyes. Most tentacles deliver a small and harmless sting these ones will kill you in two minutes.

It’s no surprise that the Box Jellyfish is one of the most feared ocean-dwelling predators out there. Unlike sharks or deep-sea giant squids, the Box Jellyfish can be small, hard-to-see, and deadly from a tiny touch.

Above you’ll see Australian professor and the world’s only jellyfish fetishist Jamie Seymour, a madman marine biologist who willingly picks up Box Jellies in the name of science. His objective for the video above (apart from scaring you away from the ocean forever) is to show just how spectacular this animal at the bottom of the evolutionary tree can be. They can swim at the speed of an Olympic athlete and they actively hunt. And any contact with them without an antidote? You’ll be dead in two minutes. That’s not bad for an animal made up of 96% water.


The Irukandji jellyfish exists in the northern waters of Australia. The southern extent of the Irukandji's range on Australia's eastern coast has been gradually moving south.

There has been an increased incidence of Irukandji stings reported around Great Palm Island, off the coast of north Queensland near Townsville. By early December 2020, the number of stings reported, at 23, was nearly double that of the whole of 2019, at 12. [11]

Some are believed to have spread farther north as symptoms of the species have been experienced off the coasts of Florida, Japan and Britain.

Irukandji jellyfish are very small, with a bell about 5 millimetres (0.20 in) to 25 millimetres (0.98 in) wide and four long tentacles, which range in length from just a few centimetres up to 1 metre (3.3 ft) in length. [12]

Malo maxima mature irukandji typically have halo-like rings of tissue around their four tentacles. Apparently, it is the mature Irukandji that are highly venomous (in all species). Apparent Malo maxima juveniles have been identified without the halo-rings, and without gonads, and have demonstrated far weaker toxicity in stinging researchers. [3] The stingers (nematocysts) are in clumps, appearing as rings of small red dots around the bell and along the tentacles. [12]

The Irukandji's small size and transparent body make it very difficult to see in the water. [3]

Very little is known about the life cycle and venom of Irukandji jellyfish. This is partly because they are very small and fragile, requiring special handling and containment. [ citation needed ] Their venom is very powerful. They were erroneously blamed for killing 5 tourists during a 3-month period in Australia. [13] In fact, no evidence exists to suggest that any of the five victims displayed two universal features of Irukandji syndrome: delayed onset (5-40 min to illness and 2-12 hrs to death) and highly visible distress (vomiting, difficulty breathing, extreme pain, etc). [14] Researchers conjecture that the venom possesses such potency to enable it to quickly stun its prey, which consists of small and fast fish. Judging from statistics, it is believed that the Irukandji syndrome may be produced by several species of jellyfish, but only Carukia barnesi and Malo kingi have so far been proven to cause the condition. [3] [15]

Unlike most jellyfish, which have stingers only on their tentacles, the Irukandji also has stingers on its bell. Biologists have yet to discover the purpose of this unique characteristic. The hypothesis is that the feature enables the jellyfish to be more likely to catch its prey of small fish. [3]

Irukandji jellyfish have the ability to fire stingers from the tips of their tentacles and inject venom. [16]

Irukandji jellyfish's stings are so severe they can cause fatal brain hemorrhages and on average send 50-100 people to the hospital annually. [17]

Robert Drewe describes the sting as "100 times as potent as that of a cobra and 1,000 times stronger than a tarantula's". [18]

Between 1 January and early December 2020, 23 stings, seven of which required admission to hospital for Irukandji syndrome, were sustained in the waters around Palm Island, off northern Queensland. [11]

Irukandji syndrome is produced by a small amount of venom and induces excruciating muscle cramps in the arms and legs, severe pain in the back and kidneys, a burning sensation of the skin and face, headaches, nausea, restlessness, sweating, vomiting, an increase in heart rate and blood pressure, and psychological phenomena such as the feeling of impending doom. [19] The syndrome is in part caused by release of catecholamines. [12] The venom contains a sodium channel modulator. [12]

The sting is moderately irritating the severe syndrome is delayed for 5–120 minutes (30 minutes on average). The symptoms last from hours to weeks, and victims usually require hospitalisation. Contrary to belief, researchers from James Cook University and Cairns hospital in far north Queensland have found that vinegar promotes the discharge of jellyfish venom. "You can decrease the venom load in your victim by 50 per cent," says Associate Professor Jamie Seymour from the Australian Institute of Tropical Health and Medicine at the university. "That's a big amount, and that's enough to make the difference, we think, between someone surviving and somebody dying." [20] Other research indicates that while vinegar may increase the discharge from triggered stingers, it also prevents untriggered stingers from discharging since the majority of stingers do not trigger immediately, the Australian Resuscitation Council continues to recommend using vinegar. [21]

Treatment is symptomatic, with antihistamines and anti-hypertensive drugs used to control inflammation and hypertension intravenous opioids, such as morphine and fentanyl, are used to control the pain. [20] Magnesium sulfate has been used to reduce pain and hypertension in Irukandji syndrome, [22] although it has had no effect in other cases. [23]

Irukandji jellyfish are usually found near the coast, attracted by the warmer water, but blooms have been seen as far as five kilometres offshore. When properly treated, a single sting is normally not fatal, but two people in Australia are believed to have died from Irukandji stings in 2002 during a rash of incidents on Australia's northern coast attributed to these jellyfish [3] [24] [25] [26] —greatly increasing public awareness of Irukandji syndrome. It is unknown how many other deaths from Irukandji syndrome have been wrongly attributed to other causes. It is also unknown which jellyfish species can cause Irukandji syndrome apart from Carukia barnesi and Malo kingi. [27]

What makes a giant jellyfish's sting deadly?

With summer on the way, and some beaches reopening after COVID-19 shutdowns, people will be taking to the ocean to cool off on a hot day. But those unlucky enough to encounter the giant jellyfish Nemopilema nomurai (also known as Nomura's jellyfish) might wish they had stayed on shore. Now, researchers reporting in ACS' Journal of Proteome Research have identified the key toxins that make the creature's venom deadly to some swimmers.

Found in coastal waters of China, Korea and Japan, Nomura's jellyfish can grow up to 6.6 feet in diameter and weigh up to 440 pounds. This behemoth stings hundreds of thousands of people per year, causing severe pain, redness, swelling, and in some cases, even shock or death. The jellyfish's venom is a complex brew of numerous toxins, some of which resemble poisons found in other organisms, such as snakes, spiders, bees and bacteria. Rongfeng Li, Pengcheng Li and colleagues wanted to determine which of the many toxins in the jellyfish's venom actually cause death. The answer could help scientists develop drugs to counteract jellyfish stings.

The researchers captured N. nomurai jellyfish off the coast of Dalian, China, and collected their tentacles, which contain the venom. They extracted venom proteins and separated them into different fractions using chromatography. By injecting each protein fraction into mice, the team identified one that killed the animals. Autopsies revealed damage to the mice's heart, lungs, liver and kidneys. The researchers used mass spectrometry to identify 13 toxin-like proteins in this lethal fraction. Some of the jellyfish proteins were similar to harmful enzymes and proteins found in poisonous snakes, spiders and bees. Instead of any one toxin being lethal, it's likely that multiple poisons work in concert to cause death, the researchers say.

Jellyfish almost killed this scientist. Now, she wants to save others from their fatal venom

TALAO-TALAO, THE PHILIPPINES—On 17 June, several families were celebrating Father's Day here at Dalahican Beach, a popular bathing spot near Lucena, a city on Luzon island. A steady breeze blew across sand that looked like fine brown sugar. Children splashed in the dark green water. Suddenly, people started to scream as a toddler was lifted unconscious from the water, his lips pale. A witness recalled that dark lashes crawled across the toddler's thighs—the telltale marks of a jellyfish sting. The boy's family simply held him and cried. Shortly after, Prince Gabriel Mabborang, 18 months old, was dead—one of at least three children killed in the Philippines this summer by the stings of box jellyfish.

On a midmorning 3 weeks later, Angel Yanagihara, who studies jellyfish venom at the University of Hawaii (UH) in Honolulu, arrived at Dalahican Beach. After slipping into a full-body wetsuit, she slung a box over her shoulder, put on gloves, and walked into the sea. No reminders of the recent tragedy were present children were playing in the shallows, clapping their hands to Filipino songs. "Hello! What's your name?" they giggled as Yanagihara, 58, walked by. Yanagihara spent almost 3 hours wading in waist-deep waters, hoping to catch box jellyfish for her studies of their venom. One of the nearly transparent animals swam to the surface, almost within reach, but then escaped as she approached. She emerged empty-handed, but villagers had brought her two specimens earlier that day.

Among the world's public health problems, jellyfish stings may seem trivial, affecting millions of people each year but known to kill only a few dozen. But many deaths may go unrecorded, and in some places, jellyfish stings take a real toll. Prince Gabriel was the second child killed on the same beach in the past year, and many people in the area bear the scars of nonfatal attacks. After news of the boy's death spread rapidly on social media, Lucena health officials invited Yanagihara to talk about jellyfish venom and how to save sting victims, a service she provided for free. She spoke at a basketball court by the beach, and as she flipped to her slide on first aid, cellphones rose in a wave, snapping photos.

Her message was clear—and controversial. Yanagihara has staked out one corner in a debate over how the venom of box jellyfish kills, stopping the heart in as little as 5 minutes. What she calls her unified field theory holds that the venom contains proteins that puncture red blood cells and release potassium, disrupting the electrical rhythms that keep the heart beating. Her conclusions, and the treatments she has based on them, emerged from 20 years of science that colleagues praise as thorough and imaginative. Yanagihara "has done a great favor to the field in doing systematic comparisons" of methods to collect and study the venom, says Kenneth Winkel, a former director of The University of Melbourne's Australian Venom Research Unit who is now at the university's Melbourne School of Population and Global Health.

But nobody has independently replicated Yanagihara's methods and findings or tested her treatments. Some jellyfish researchers say other compounds in the venom are the real killers and that different remedies—or none at all—are more likely to work. "Jellyfish venom is a graveyard for simplistic causation and therapy," Winkel says.

Research that would resolve the debates is scarce. Worldwide, only about five research groups study jellyfish venom. Funders prefer to focus on bigger public health problems—although Yanagihara thinks the stings exact a much higher death toll than most people assume. So she and her few colleagues and competitors struggle on with small budgets to study the threat, develop remedies, and educate communities at risk.

Most of the 4000 species of jellyfish cause only pain and discomfort when they sting humans. Only Cubozoans, or box jellyfish, of which some 50 species inhabit tropical and temperate seas around the globe, are fatal. They take their name from their cubic body, which has between four and 15 tentacles up to 3 meters long growing from each of the four corners. The tentacles are carpeted with hundreds of thousands of specialized cells, each harboring a capsule called a nematocyst that can fire a microscopic harpoon at speeds of more than 60 kilometers per hour. The harpoon carries a spiny hollow tube that injects venom after it strikes a victim.

Yanagihara, born in Alaska, hadn't planned to study jellyfish. But in 1997, the year she obtained her Ph.D. at UH for research on cellular ion channels, the jellyfish found her. One day that year, Yanagihara swam out to sea before dawn—"My father taught me to swim before I walked," she says—when she encountered a swarm of box jellyfish some 500 meters offshore. She felt needles burning into her neck and arms and her lungs collapsing her arms began to fail. She switched to a breathing technique she had learned for childbirth and clawed back to shore in agony, "like an automaton." The pain kept her in bed for 3 days. After she recovered, she wanted to know what almost killed her.

In some cases, box jellyfish venom causes Irukandji syndrome, in which an overload of stress hormones and inflammation proteins produces pain and nausea for days, as well as high blood pressure that can lead to brain hemorrhage and death. Most sting casualties, however, die within minutes from cardiac arrest. The prevailing hypothesis 20 years ago was that the culprits are ion channel blockers, molecules that disrupt movement of ions in and out of cells. The blockage shuts down nerve and muscle cells, including those that keep the heart pumping.

To test the idea, Yanagihara followed a standard procedure for studying jellyfish venom: She dissolved the tentacles in water to release the nematocysts and broke them with a mortar and pestle or glass beads to release the venom. Then she exposed immature frog egg cells—a common model in cell physiology—to the venom and measured ion movement using electrophysiological techniques. But the experiments kept failing. After scrutinizing every part of her experimental setup, she began to wonder whether her venom preparation was too impure to reveal its secrets. She realized that crushing the nematocysts produced a crude mix of venom and cellular debris—akin to putting "a rattlesnake in a blender" to get its venom, she says.

Taking a cue from a 1970s study, she developed a new method that uses citrate, an acidic compound, to dislodge the nematocysts without breaking them. She then puts them in a French press, in which a piston forcibly ruptures all the nematocysts at once. A minuscule harvest of venom squeezes out through a tiny outlet that filters larger cellular components.

The yield is excruciatingly low: some 10 milliliters of venom from 1000 box jellyfish. (Yanagihara collects a species named Alatina alata, often called the sea wasp, en masse in Hawaii.) But the result, she says, is a much purer venom. In it she found not only ion channel blockers, but also many porins, proteins that puncture cells, allowing their contents to leak out. She suspected hemolysis—the destruction of red blood cells by porins—might be the fatal mechanism.

Watch the video: Πρώτες βοήθειες αν σε τσιμπήσει τσούχτρα (May 2022).