How To Treat Jellyfish Stings & What To Do To Avoid Getting Stung While Snorkeling

Jellyfish stings are among the most common incidents for beachgoers, snorkelers, and swimmers. Therefore, most people fear these creatures, even though most species are harmless or cause only short-term discomfort if contacted. To break down the misconceptions and clarify potential threats, we discuss the most critical information about jellyfish, a step-by-step guide on what to do when stung by a jellyfish, and some tips on avoiding encountering them.

What are jellyfish?

Jellyfish -often called jellies, sea jellies, and medusas- are some of the most fascinating and bizarre creatures on the earth. They are not fish but belong to the group of invertebrates, are related to sea anemones and corals, and are composed of a jellylike substance comprising about 95% water and only 5% structural proteins like nerves and muscles. Their dome, mushroom, or bell-shaped body is ringed with numerous tentacles.

Jellies have no heart, bones, or eyes, and they do not have brains either; they detect their surroundings through the nerves at the base of their tentacles.

Most jellies have limited control over their movements. They propel themselves forward by expanding and contracting their bell and usually drift in currents. Therefore, they are often found in large masses, called jellyfish bloom or smack of jellyfish.

Where are jellies found?

Jellyfish have existed for at least 500-700 million years and live all over the world in any sort of water; most species are found in the ocean, but some even in freshwater.

They thrive in warm waters but are abundant in the icy Arctic. Although they usually swim near the surface, scientists have also discovered them in the deepest depths.

Shallow, warm water coastline areas provide the most excellent conditions for jellyfish. Therefore, they appear in large numbers at popular tourist destinations in the summertime, and this is when beachgoers, swimmers, and snorkelers encounter them and, in unlucky scenarios, get stung by them.

What time of the year jellyfish are the most active?

Warm waters provide the best conditions for jellies and their ilk, meaning their appearance coincides with the peak tourist season. But this does not mean you must avoid beach destinations during the summer months or that you cannot go swimming, just be prepared for accidental contacts.

How do jellyfish sting?

Jellyfish sting with their tentacles for two reasons: when they defend themselves and when they hunt for food. The ‘long arms’ are covered with special cells called cnidocytes. These cells contain specialized structures (nematocysts) working like tiny harpoons; upon contact – or with human skin – they release venom-filled tubes into the prey, and the released toxin paralyzes the target.

This toxin is usually strong enough to paralyze crustaceans or smaller fish, so a typical sting only causes red marks, itching, numbness, or burning sensation on the skin. Interestingly, some jellies can sting despite having no tentacles; the so-called upside-down Cassiopea jellyfish releases a sticky slime full of stingers to trap its prey. If swimming through this cloud, even humans can experience a stinging sensation in the water and, later, extraordinary itching.

How many tentacles does a jellyfish have?

Depending on the species, jellyfish usually have four to eight tentacles, but some have hundreds. The tentacles vary in size, too; generally, they reach 1-3 feet/0.3-1m in length, but there are species with tentacles up to 100-120 feet/30-36m long, such as the Lion’s mane.

Do all jellyfish sting?

Although about 150 million people suffer jellyfish stings each year, only certain species can be harmful to humans. For instance, one of the most common jellies found throughout the world’s oceans, the moon jelly – which is easily recognizable from its purple-colored, translucent body – is completely harmless along with many other species, such as the famous Palau’s Golden Jellyfish or the globe-shaped, rainbow-like colored sea gooseberries.

This, however, does not mean that such jellies are non-stinging; in fact, their sting is not strong enough to get through human skin, or their venom is so mild that most people do not show any reaction to it.

Jellyfish sting symptoms

In most cases, if you get stung by jellyfish, it will cause discomfort and localized symptoms on the affected body area where the tentacles have contacted the skin.

What does a jellyfish sting look like?

When a jellyfish stings a person, the tiny stingers (nematocysts) released often leave a visible sign on the skin that looks like the print of the tentacle. These track marks can become irritated and painful, may give a burning sensation, and cause the victim to experience redness and an itchy rash at the sting site.

How to treat a jellyfish sting?

The treatment of a jellyfish sting always depends on the type of jellyfish, how extensive the affected skin area is, and how one’s body reacts to it. Although they can cause discomfort, most stings do not require medical care, just first aid, directly at the beach where the incident happened.

If you have vinegar available, you can rinse the area with that, too. Since vinegar is an acid, it neutralizes the unfired nematocysts and can prevent further venom release.

Until the sore heals, you may cover it with a thin layer of antiseptic cream to cleanse and prevent infection. You may also take non-steroidal anti-inflammatory drugs to reduce pain.

If you do not have the right accessories or can’t reach the area where you got stung, go to the nearest first aid point or lifeguard station for help.

Does urine help jellyfish stings?

There are various myths associated with jellyfish stings and one of the most common ones is that you should pee on it. This assumption may originate from the fact that urine contains substances like ammonia and urea. If such compounds are used alone, they may help with certain stings, but in human pee, they are diluted in water and found at very low levels, so are not effective.

Instead, urinating on the sting may spread the venom over the skin and increase the risk of infection; therefore, the best is to forget about the pee cure.

Author’s note: The same applies to cleaning the wound with alcohol and rubbing sand on it. You may have seen these techniques in movies, but they would also spread the venom and cause infection.

How long does a jellyfish sting last?

Symptoms usually remit after a short period; pain should last only a few hours, and skin reaction should last a few days. If the person’s condition that got stung gets suddenly worse, the skin irritation, redness, or pain does not go away, or new symptoms develop, medical help may be necessary.

Severe reactions

Only in rare cases do jellyfish stings cause life-threatening conditions, but those who get stung on very sensitive areas (near the eye, mouth, or genitals), have allergies or other underlying conditions or make contact with a dangerous species might develop extreme symptoms.

Factors that determine the severity of the victim’s reaction

Delayed reaction to a jellyfish sting

Those who suffer from hypersensitivity – an allergic immune reaction – may experience delayed skin reactions. Rash, swelling, and itching can occur hours, days, or even weeks after the sting and can be followed by weakness, chest pain, or fever. Depending on the patient’s condition, it may be advisable to see a doctor to prevent complications.

Can jellyfish sting when dead?

Jellies’ stingers, the nematocysts, are microscopic, non-living structures that only release their toxins when they come in contact with an object. This means the stinging cells can keep firing in the tentacles for hours after the jellyfish has died.

Therefore, those that have washed up onshore may still sting even when looking dead, so be careful to avoid stepping in one when walking on the beach or wading in the water.

The most dangerous jellyfish in the world

While casual beach activities are rare, the possibility of encountering dangerous jellyfish is high, but they may be out there, so it is crucial to be able to identify those species that pose a potential risk to humans.

Portuguese Man-o-war

The Portuguese Man-o-War is not a single jellyfish but a group of animals containing four separate polyps. It got its name because its gas-filled uppermost polyp sits above the water and looks like a warship at full sail. These species live mostly in warmer seas, and since they float on the surface, they are mostly propelled by winds.

Man-o-war has very long tentacles and potent venom. However, it is rarely deadly. Its sting leaves red welts on the skin and can cause respiratory problems and extreme pain.

Lion’s mane

One of the world’s largest jelly species, Lion’s mane, lives in cooler waters in the North Pacific Ocean. It can be found mainly near Alaska and Washington and in especially large numbers around Ireland. It typically grows up to 1.5 feet (40 cm), but some reach 9.8 feet (3m). It’s easy to see why this species was named after the lion; hundreds of long, orange-brownish hair-like tentacles surround its body.

The sting of a Lion’s mane is powerful and can be very painful. It is rarely fatal but can cause severe allergic reactions, so if you experience swelling, fever, headache, dizziness, breathing difficulties, fever, or nausea, consult a doctor.

Chironex fleckeri box jellyfish

Known as a sea wasp, Chironex Fleckeri is a type of box jelly. This species is usually found in northern Australia and the Indo-Pacific region, including the Philippines, Malaysia, and New Guinea.

It has a small box-shaped body with long (10ft/3m) tentacles. Its painful venom causes irritated red tracks and excruciating pain, and in extreme cases, can lead to fatality.

Irukandji

Appearing once only in Australian waters but have spread farther to Thailand, Japan, Florida and even to Britain, the Irukandji – a certain box jellyfish – means a growing concern. Its transparent body and small size – about the size of a fingernail – make it difficult to see, and therefore to avoid in the water. A sting by an Irukandji is so special that it even got its own name, Irukandji Syndrome.

The victim may experience first only mild symptoms, but severe pain, muscle and stomach cramps along with vomiting and burning skin sensation, in worse cases cardiac complications are following it generally in 30 minutes to 4-12 hours after the incident.

Although this species is undoubtedly among the most dangerous in the world, the good news is that people typically survive its sting when receiving proper treatment.

How to prevent jellyfish stings?

Even though jellyfish populations are increasing globally, swimmers and snorkelers likely do not encounter dangerous ones, just species with mild or no stings, so there is no reason to fear the ocean. Also, here are some great tips to avoid getting stung so your pleasant day at the beach won’t be ruined.

Wear a protective suit (rash guard or wetsuit)

When swimming, snorkeling, or diving in areas where stingers may be present, the best way to avoid getting stung is to wear protective suits. Special stinger suits are available, but your regular UV protection clothing, rash guard, or wetsuit – depending on the water temperature – will also do the job.

For the highest level of protection, choose long-sleeved shirts and pants and wear beach shoes while wading in shallow water. Also, even when only swimming, wear goggles so you can see your surroundings in the water.

Use jellyfish-repellent sunscreen

Alternatively, you can use a Safe Sea sting-blocking sunblock. This combination product provides protection against UV radiation but also contains special ingredients that keep you safe from jellyfish by inactivating the stinging cells. Apply it like a normal sunscreen before entering the water.

Check local forecasts

Most popular beach destinations have weather pages that issue daily recommended beach maps in the peak season. These maps let you know the state of the area’s beaches, including water quality, currents, waves, and jellies. Sometimes, even apps are available to download.

Always check if such forecasts are available, and if so, follow their recommendations to find the safest beaches. If not, get information from lifeguards, local health departments, residents, and other beachgoers.

Educate yourself about jellyfish

The appearance of jellies is well predictable. By studying some marine biology, you will not only learn interesting facts about these fascinating creatures but will also know what species you can encounter in the area you are planning to swim in and when the jellyfish season is.

Also, coastline destinations know when these creatures swarm along the beaches and when it is advisable to avoid entering the water. Often, warning signs are placed out with pictures of the jellies present in the area along with a short description that suggests whether that specific species is harmless or not and what to do if one accidentally gets stung. Study these guides and take a photo of them to always have the information on hand when needed.

Why are there so many jellyfish?

Jellyfish numbers are increasing worldwide due to four main factors: climate change, human intervention, overfishing, and pollution.

Climate change

The changing climate -warming sea temperatures, acidification – also supports jellies to reproduce more quickly. Unlike most marine creatures, they aren’t vulnerable to warm water temperatures, low oxygen or high acidity levels but thrive in such conditions.

Human intervention

Man-made structures and human activity-related objects such as maritime shipping vessels, docks, and oil and gas production platforms also benefit the reproduction of jellies. The larvae need to hook on a solid surface where they stay for several weeks or months and grow into another stage of their life. With the increasing number of such objects in our waters, more and more larvae become adult jellyfish.

Overfishing

Due to harmful fishing practices, fish are being removed from the water at a rate more significant than the population can replenish itself. The use of commercial fishing nets increased the rate of bycatch too when non-target marine species such as turtles and dolphins are caught too. Due to these bad fishing practices, their natural predators disappear so jellies can bloom.

Pollution

Agricultural and urban pollution, such as fertilizers and sewage, run off the land and end in the sea, raising the level of nutrients in the water. Such conditions allow plankton and algal blooms, decreasing the oxygen level, killing fish and other marine animals but creating a favorable environment for jellyfish.

Conclusion

Millions of jellyfish live in our oceans, and their numbers are rapidly increasing, but there is no need to be afraid of encountering one along the coast or in the water. Most jellies beachgoers encounter have no potent venom, and their sting causes only skin irritation, redness, and mild pain. Still, with the appearance of dangerous species beyond their usual habitats, it is essential to know how to identify a sting and the best treatment for it. Learning what species can be present in the area you live or travel to and wearing a long-sleeve protection suit in the water can lower the risk of getting stung.

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