What are the dangers of jellyfish stings. How can you identify a jellyfish sting. What is the proper treatment for a jellyfish sting. When should you seek emergency medical care for a jellyfish sting. How can jellyfish stings be prevented.

Understanding Jellyfish and Their Stinging Mechanism

Jellyfish are ancient marine creatures that have inhabited our oceans for millions of years. These fascinating organisms come in various shapes and sizes, ranging from small, transparent blobs to larger, more colorful species with trailing tentacles. Despite their diverse appearances, all jellyfish share a common defensive and predatory mechanism: their ability to sting.

Jellyfish use their tentacles, which are equipped with specialized cells called nematocysts, to sting their prey and potential threats. When triggered, these nematocysts release venom that can paralyze small marine animals and cause pain and discomfort in humans.

How do jellyfish stings occur?

Jellyfish stings typically happen when a person comes into direct contact with a jellyfish’s tentacles. This can occur while swimming, wading in shallow water, or even walking on the beach where dead jellyfish may have washed ashore. It’s important to note that jellyfish do not actively seek out humans to sting; most encounters are accidental.

• Swimming or floating into a jellyfish
• Touching a jellyfish while in the water
• Stepping on a beached jellyfish (even dead ones can still sting)
• Handling jellyfish remains on the shore

Identifying Jellyfish Sting Symptoms

Recognizing the symptoms of a jellyfish sting is crucial for proper treatment and determining the severity of the incident. While the intensity of symptoms can vary depending on the species of jellyfish and the extent of contact, there are several common signs to watch for:

What are the typical symptoms of a jellyfish sting?

Most jellyfish stings result in immediate localized symptoms, including:

• Intense burning or stinging sensation
• Red, swollen welts or track-like marks on the skin
• Itching or tingling
• Numbness in the affected area
• Mild to moderate pain

In some cases, particularly with more dangerous species like the box jellyfish, additional systemic symptoms may occur:

• Muscle spasms or weakness
• Nausea and vomiting
• Headache and dizziness
• Difficulty breathing
• Changes in heart rate or blood pressure

Dangerous Jellyfish Species and Their Habitats

While most jellyfish stings are painful but not life-threatening, certain species pose a significant risk to human health. Understanding which jellyfish are more dangerous and where they are commonly found can help beachgoers and swimmers take appropriate precautions.

Which jellyfish species are considered most dangerous?

The box jellyfish, also known as the sea wasp, is widely regarded as one of the most venomous marine animals in the world. Its sting can cause severe pain, cardiovascular collapse, and even death in some cases. Other dangerous species include:

• Irukandji jellyfish
• Portuguese man-of-war
• Lion’s mane jellyfish
• Sea nettle

These dangerous jellyfish species are primarily found in the following regions:

• Northern Australia
• Southeast Asian waters
• Indian Ocean
• Central Pacific Ocean
• Atlantic Ocean (Portuguese man-of-war)

Proper Treatment for Jellyfish Stings

Prompt and appropriate treatment of jellyfish stings is essential to minimize pain, prevent further envenomation, and reduce the risk of complications. The recommended treatment may vary depending on the type of jellyfish involved and local medical guidelines.

What is the recommended first aid for jellyfish stings?

When treating a jellyfish sting, follow these general steps:

1. Remove the person from the water to prevent further stings.
2. Rinse the affected area with vinegar for at least 30 seconds. Vinegar helps neutralize unfired nematocysts and prevent further venom release.
3. Do not rinse with fresh water, as this can cause more nematocysts to fire.
4. Avoid rubbing the area, which can worsen the sting.
5. Use tweezers to carefully remove any visible tentacles from the skin.
6. Apply a hot compress or immerse the affected area in hot water (as hot as can be tolerated without burning) for about 20 minutes to help relieve pain.
7. Consider over-the-counter pain relievers if needed.

It’s important to note that some older treatments, such as urinating on the sting or applying meat tenderizer, are not recommended and may be ineffective or harmful.

When to Seek Emergency Medical Care

While many jellyfish stings can be treated at home, certain symptoms or circumstances warrant immediate medical attention. Recognizing these signs can be crucial in preventing severe complications or life-threatening reactions.

What are the signs that a jellyfish sting requires emergency care?

Seek immediate medical assistance if the person experiencing a jellyfish sting exhibits any of the following symptoms:

• Difficulty breathing or swallowing
• Swelling of the tongue or lips
• Changes in voice
• Severe or widespread pain
• Nausea or vomiting
• Dizziness or severe headache
• Muscle spasms
• Stings covering a large portion of the body
• Stings to sensitive areas such as the eyes or mouth
• Signs of a severe allergic reaction (anaphylaxis)

Additionally, if you suspect the sting is from a highly venomous species like the box jellyfish, seek emergency care regardless of the initial symptoms.

Preventing Jellyfish Stings

While it’s impossible to completely eliminate the risk of jellyfish stings when enjoying marine environments, there are several precautions you can take to minimize the likelihood of an encounter.

How can you reduce the risk of jellyfish stings?

Consider the following preventive measures when visiting beaches or engaging in water activities:

• Stay informed: Check local beach conditions and warnings for jellyfish activity.
• Observe warning flags: Many beaches use purple flags to indicate the presence of dangerous marine life.
• Wear protective clothing: Consider using a wetsuit or lycra “stinger suit” when swimming in jellyfish-prone areas.
• Use caution in shallow waters: Be aware that jellyfish can be present in shallow coastal areas, not just in deep water.
• Avoid touching marine life: Refrain from handling jellyfish or their remains on the beach.
• Carry a first aid kit: Include vinegar and tweezers in your beach bag for quick treatment if needed.
• Choose guarded beaches: Lifeguards are more likely to be aware of and warn about jellyfish presence.

Understanding Jellyfish Ecology and Behavior

To better appreciate and coexist with jellyfish, it’s valuable to understand their ecological role and behavioral patterns. This knowledge can also help in predicting and avoiding potentially dangerous encounters.

What factors influence jellyfish populations and distribution?

Jellyfish populations and their distribution in the oceans are influenced by various environmental factors:

• Water temperature: Many jellyfish species thrive in warmer waters, leading to population blooms during hot seasons.
• Ocean currents: Jellyfish are often carried by currents, which can lead to sudden appearances in new areas.
• Food availability: Increases in plankton populations can support larger jellyfish numbers.
• Climate change: Rising ocean temperatures and changing marine ecosystems may be contributing to increased jellyfish populations in some regions.

Understanding these factors can help predict when and where jellyfish are more likely to be encountered, allowing for better preparation and prevention strategies.

Jellyfish Sting Research and Future Treatments

As marine ecosystems continue to change and human interactions with jellyfish increase, ongoing research is crucial for developing better prevention and treatment strategies for jellyfish stings.

What are some recent advancements in jellyfish sting treatment?

Scientists and medical researchers are continually working to improve our understanding and management of jellyfish stings. Some recent areas of focus include:

• Venom analysis: Studying the composition of different jellyfish venoms to develop more targeted treatments.
• Antidote development: Research into potential antidotes for highly venomous species like the box jellyfish.
• Pain management: Exploring new methods for rapid pain relief following jellyfish stings.
• Prevention technologies: Developing more effective protective gear and repellents to prevent stings.

These ongoing efforts aim to enhance our ability to prevent, treat, and manage the impact of jellyfish stings on human health and marine recreation.

Jellyfish Stings (for Parents) – Nemours KidsHealth

en español: Picaduras de medusas

Medically reviewed by: Larissa Hirsch, MD

What Are Jellyfish Stings?

Jellyfish have been around for millions of years and live in oceans all over the world. There are many different types of jellyfish. Some just look like small, clear blobs, while others are bigger and more colorful with tentacles hanging beneath them.

Jellyfish sting their prey with their tentacles, releasing a venom that paralyzes their targets. Jellyfish don’t go after humans, but someone who swims up against or touches one — or even steps on a dead one — can be stung all the same.

While jellyfish stings are painful, most are not emergencies. Expect pain, red marks, itching, numbness, or tingling with a typical sting.

But stings from some types of jellyfish — such as the box jellyfish (also called sea wasp) — are very dangerous, and can even be deadly. These jellyfish are most often found in Australia, the Philippines, the Indian Ocean, and central Pacific Ocean.

How Are Jellyfish Stings Treated?

Jellyfish stings leave thousands of very tiny stingers called nematocysts in the skin. These stingers can continue to release (or “fire”) jellyfish venom (poison) into the body. Treatment can vary based on the type of jellyfish most common in the area.

Often, it’s best to rinse a sting with vinegar. Vinegar is a weak acid that might keep the stingers from firing for some kinds of stings (especially from dangerous types like box jellyfish).

Do not rinse with fresh water (like tap or bottled water) because that can make more stingers fire. Rinsing a sting with seawater may prevent stingers from releasing more venom.

Also, do not scrape off any stingers still in the skin. This used to be recommended, but now is thought to make stings worse.

To deal with a sting:

• Remove your child from the water.
• Rinse the area with vinegar. (Keep a small plastic bottle of vinegar in your beach bag, just in case. )
• Don’t rub the area, which can make things worse.
• Use tweezers to pluck away any tentacles still on the skin. Do not scrape the area with a credit card or other stiff card.
• A hot (but not scalding) shower or soak may help lessen pain.
• Check in with your health care professional to see if pain relievers might help your child feel better.

Call an ambulance right away if someone has been stung and:

• has trouble breathing or swallowing
• has a swollen tongue or lips, or a change in voice
• has bad pain or feels generally unwell
• is nauseated or vomiting
• is dizzy or has a headache
• has muscle spasms
• has stings over a large part of the body
• the sting is in the eye or mouth
• might have been stung by a very dangerous jellyfish

Can Jellyfish Stings Be Prevented?

Beaches with lifeguards are more likely to warn visitors about jellyfish. Look for a sign or warning flag (some beaches fly a purple warning flag when there’s “dangerous marine life” in the water). Double check to make sure that you’ve got a small container of vinegar and a pair of tweezers in your beach bag.

Medically reviewed by: Larissa Hirsch, MD

Date reviewed: May 2022

Share:

/content/kidshealth/misc/medicalcodes/parents/articles/jellyfish

Jellyfish stings Information | Mount Sinai

Jellyfish are sea creatures. They have nearly see-through bodies with long, finger-like structures called tentacles. Stinging cells inside the tentacles can hurt you if you come in contact with them. Some stings can cause serious harm. Almost 2000 species of animals found in the ocean are either venomous or poisonous to humans, and many can produce severe illness or fatalities.

This article is for information only. DO NOT use it to treat or manage a jellyfish sting. If you or someone you are with is stung, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

Poisonous Ingredient

Jellyfish venom

Where Found

Types of potentially harmful jellyfish include:

• Lion’s mane (Cyanea capillata).
• Portuguese man-of-war (Physalia physalis in the Atlantic and Physalia utriculus in the Pacific).
• Sea nettle (Chrysaora quinquecirrha), one of the most common jellyfish found along the Atlantic and Gulf coasts.
• Box jellyfish (Cubozoa) all have a box-like body or “bell” with tentacles extending from each corner. There are over 40 species of box jellies. These range from nearly invisible thimble-sized jellyfish to basketball-sized chirodropids found near the coasts of northern Australia, Thailand, and the Philippines (Chironex fleckeri, Chiropsalmus quadrigatus). Sometimes called “sea wasps,” box jellyfish are highly dangerous, and more than 8 species have caused deaths. Box jellyfish are found in the tropics including Hawaii, Saipan, Guam, Puerto Rico, the Caribbean, and Florida, and recently in a rare event in coastal New Jersey.

There are also other types of stinging jellyfish.

If you are unfamiliar with an area, be sure to ask local ocean safety staff about the potential for jellyfish stings and other marine hazards. In areas where box jellies may be found, especially at sunset and sunrise, full body coverage with a “stinger suit,” hood, gloves, and booties is advised.

Symptoms

Symptoms of stings from different types of jellyfish are:

LION’S MANE

• Breathing difficulty
• Muscle cramps
• Skin burning and blistering (severe)

PORTUGUESE MAN-OF-WAR

• Abdominal pain
• Changes in pulse
• Chest pain
• Chills
• Collapse (shock)
• Headache
• Muscle pain and muscle spasms
• Numbness and weakness
• Pain in the arms or legs
• Raised red spot where stung
• Runny nose and watery eyes
• Swallowing difficulty
• Sweating

SEA NETTLE

• Mild skin rash (with mild stings)
• Muscle cramps and breathing difficulty (from a lot of contact)

SEA WASP OR BOX JELLYFISH

• Abdominal pain
• Breathing difficulty
• Changes in pulse
• Chest pain
• Collapse (shock)
• Headache
• Muscle pain and muscle spasms
• Nausea and vomiting
• Pain in the arms or legs
• Raised red spot where stung
• Severe burning pain and sting site blistering
• Skin tissue death
• Sweating

For the great majority of bites, stings, or other forms of poisoning, the danger is either drowning after being stung or an allergic reaction to the venom.

Home Care

Seek medical help right away. Get medical attention right away if pain increases or there are any signs of breathing difficulty or chest pains.

• As soon as possible, rinse the sting site with large amounts of household vinegar for at least 30 seconds. Vinegar is safe and effective for all types of jellyfish stings. Vinegar rapidly halts the thousands of tiny unfired stinging cells left on the surface of the skin after tentacle contact.
• If vinegar is not available, the sting site can be washed with ocean water.
• Protect the affected area and do NOT rub sand or apply any pressure to the area or scrape the sting site.
• Soak the area in 107°F to 115°F (42°C to 45°C) standard tap hot water, (not scalding) for 20 to 40 minutes.
• After soaking in hot water, apply antihistamine or steroid creams such as cortisone cream. This can help with pain and itching.

Before Calling Emergency

Have this information ready:

• Person’s age, weight, and condition
• Type of jellyfish, if possible
• Time the person was stung
• Location of the sting

Poison Control

Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.

What to Expect at the Emergency Room

The health care provider will measure and monitor the person’s vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated. The person may receive:

• Antivenin, a medicine to reverse the effects of the venom, may be used for one specific box jelly species found only in certain areas of the Indo-Pacific (Chironex fleckeri)
• Blood and urine tests
• Breathing support, including oxygen, a tube through the mouth into the throat, and breathing machine
• Chest x-ray
• ECG (electrocardiogram, or heart tracing)
• Fluids through a vein (by IV)
• Medicine to treat symptoms

Outlook (Prognosis)

Most jellyfish stings improve within hours, but some stings can lead to skin irritation or rashes that last for weeks. Contact your provider if you continue to have itching at the sting site. Topical anti-inflammatory creams may be helpful.

Portuguese man-of-war and sea nettle stings are rarely deadly.

Certain box jellyfish stings can kill a person within minutes. Other box jellyfish stings can lead to death in 4 to 48 hours after a sting due to “Irukandji syndrome,” a delayed reaction to the sting.

It is important to carefully monitor box jellyfish sting victims for hours after a sting. Seek medical attention right away for any breathing difficulties, chest or abdominal pains, or profuse sweating.

Feng S-Y, Goto CS. Envenomations. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 746.

Otten EJ. Venomous animal injuries. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 55.

Scerri L. Jellyfish stings. In: Lebwohl MG, Heymann WR, Coulson IH, Murrell DF, eds. Treatment of Skin Disease: Comprehensive Therapeutic Strategies. 6th ed. Philadelphia, PA. Elsevier; 2022:chap 116.

Last reviewed on: 7/20/2021

Reviewed by: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Jellyfish – 6 interesting facts

Jellyfish are one of the most ancient animals on Earth. They are also extremely diverse – most of the organisms called jellyfish are of the Cnidaria phylum, which includes over 10,000 species.

Tags:

Animals

Interesting Facts

Interesting

Nature

Legion-Media

Jellyfish are found in large numbers all over the world – in cold and warm water, deep in the sea or on the surface. Most people are afraid to swim near them because of their painful sting, but not all jellyfish are dangerous. Here are 6 little-known facts about these amazing creatures.

Contents of the article

Jellyfish may be older than dinosaurs

Jellyfish don’t have bones, so it’s hard to find fossils. However, scientists have evidence that these creatures have inhabited the world’s oceans for at least 500 million years. In fact, it is likely that the origin of jellyfish goes back even further, perhaps as far back as 700 million years ago. This is about three times more than the age of the first dinosaurs.

Jellyfish for 98% water

Man is 60% water and jellyfish is 98%. When washed ashore, they can disappear within hours as their bodies quickly evaporate into the air.

Jellyfish have no brain or heart, and their gelatinous bodies are so thin that they can be oxygenated solely by diffusion.

ADVERTISING – CONTINUED BELOW

Jellyfish eat almost everything in the water

Jellyfish eat different types of food. They eat many marine life such as small fish, grubs, crabs, shrimp, tiny plants, and even other jellyfish.

Some jellyfish are immortal

The lifespan of a jellyfish depends on various factors, including species, water temperature, and predators. And although some of them can live from a few hours to several months, there are also immortal specimens, for example, the jellyfish Turritopsis nutricula. In the event of a threat, this species is able to undergo cellular transdifferentiation, a process by which the cells of the body, in fact, become new.

Jellyfish come in all sizes

The largest jellyfish is the Hairy Cyanea (Cyanea capillata). In diameter, it reaches 6 meters, and its stinging tentacles can reach a length of 50 meters.

The smallest species of jellyfish is the common killer of kings (Malo kingi), which is considered one of the most poisonous creatures on the planet. It is smaller than a human fingernail in size.

Jellyfish are one of the most deadly creatures on the planet

All jellyfish have nematocysts (microscopic stinging capsules) in their tentacles, but the severity of their sting can vary greatly depending on the species.

The most poisonous jellyfish in the world are box jellyfish, capable of killing an adult human in just a few minutes with one bite. According to reports, the venom of each jellyfish is enough to kill more than 60 people. In addition, their bites are very painful. They say that people die from pain earlier than from poison.

Interesting facts about jellyfish | ZooBlog

Jellyfish are one of the most terrifying and intriguing creatures in the marine world, so it’s no surprise that children and adults alike are stunned to encounter them. Take a few minutes to enjoy the most amazing facts about the most unusual inhabitants of the seas and oceans.

Contents

• 1 Jellyfish are the oldest multicellular inhabitants of the planet
• 2 Some jellyfish can glow in the dark
• 3 A translucent bell is a distinctive feature of jellyfish
• 4 Jellyfish do not have a typical digestive system
• 5 They are found all over the world
• 6 Some jellyfish are immortal
• 7 Jellyfish can clone themselves
• 8 There is a giant jellyfish with hair
• 9 Jellyfish sting 150 million people annually
• 10 Jellyfish stings are deadly
• 11 Did you know?

Jellyfish are the oldest multicellular inhabitants of the planet

Ancient fossils found prove that jellyfish have been living in our seas and oceans for at least 600 million years! Therefore, they appeared on Earth long before dinosaurs or bony fish, before flowers, ferns or mushrooms.

Jellyfish survived five mass extinctions, including the Great Dying (or Permian-Triassic Extinction), which destroyed up to 70% of life on Earth. And while other marine animals struggle to survive in warmer, more acidic oceans, jellyfish are thriving and perhaps even more numerous.

Some jellyfish can glow in the dark

Photo: Matthias Götzke

Many jellyfish have bioluminescent organs that emit blue or green light. Light emission is usually activated by touch. The bioluminescent light serves to deter predators. It can also help in attracting prey or warning other marine life that a certain area is already occupied.

A translucent bell is a distinctive feature of jellyfish

The bell is made of a soft delicate material called mesoglea. The mesoglea, sandwiched between two layers of skin, is more than 95% water held by protein fibers. Jellyfish can contract and relax their bells to move forward.

They have no brain or spinal cord, but the nerve network around the inner edge of the bell forms a rudimentary nervous system capable of sensing ocean currents, detecting light and the touch of other animals. Jellyfish also have a sense of gravity, which allows them to navigate and move around in the water. They can even feel the nascent storm 10-15 hours before its manifestation. This time is enough for them to go into deep water.

Photo: KAL VISUALS

Jellyfish do not have a typical digestive system

These gelatinous carnivores consume plankton, crustaceans and other small sea creatures through a hole in the bottom of their bells. Nutrients that jellyfish consume are absorbed by the inner layer of cells, and waste is excreted back through the mouth.

They are found all over the world

Jellyfish are found in every ocean, in every corner of the planet, from the coldest waters of the Arctic Ocean to the warm and temperate waters of the tropical oceans. They can exist in different water conditions and at different depths, from the ocean floor to the surface. They can even be found in a number of freshwater ponds and lakes. They are usually found in shallow water, but a few species have been found as deep as 9000 meters!

Jellyfish are able to adapt in the dead zones of the ocean, where the concentration of oxygen is negligible and the percentage of pollution is high. There are over 400 such dead zones on the planet.

Jellyfish that live near the surface of the water are usually colorless. Those who live deeper are often yellow, green, lilac, red, and sometimes even distinguished by multi-colored stripes.

Photo: Travel Sourced

Some jellyfish are immortal

Have you ever dreamed of immortality? The good news is that you can become immortal. The bad news is that for this you need to turn into a jellyfish Turritopsis nutricula. This deadly species of jellyfish lives in the Mediterranean Sea and in the territorial waters of Japan.

When an immortal jellyfish becomes ill, ages, or stressed, its struggling cells can change their life cycle. The tiny bell and tentacles grow into an immature polyp that spawns new clones of its parent. Thus, the invertebrate returns from the adult stage back to the juvenile polyp stage.

Jellyfish can clone themselves

Some jellyfish can lay up to 45,000 eggs in one night. At the same time, they have a rather interesting life cycle, which includes a combination of sexual and asexual reproduction. At the polyp stage, they can asexually create several of their clones, which then grow into sexually mature individuals.

There is a giant haired jellyfish

The lion’s mane jellyfish (Cyanea capillata), also referred to as the giant jellyfish or the hairy cyanide, is considered the largest of the classified jellyfish species.

Photo: Michael Poltermann

The largest specimen was discovered on the coast of Massachusetts Bay 150 years ago. The diameter of its bell was 2.3 meters, and the length of the tentacle was 37 meters (the blue whale has much less). It is considered one of the longest known animals in the world.

Jellyfish sting 150 million people every year

This means that over 1000 people have been stung by jellyfish in the time you spent reading this article. The jellyfish’s sting, which helps it catch prey and defend itself, is its most infamous calling card. Each tentacle is armed with thousands of cnidocytes, inside which are nematocysts containing a spiral stinging thread that unwinds like a harpoon when threatened.

Spinning the small stings of a jellyfish is one of the fastest actions in nature, it is faster than a bullet. It is noteworthy that the tentacle of a jellyfish can sting even after separation from the body.

The best thing to do after a jellyfish sting is to wash the affected part with salt water (not fresh water). Salt water deactivates the stinging cells, while fresh or tap water activates them again. Vinegar can help, but alcohol or alkaline substances will only aggravate the situation.

Jellyfish stings are deadly

Jellyfish venom is one of the most powerful poisons among the representatives of the animal world. The Australian box jellyfish (Chironex fleckeri), also referred to as the “sea sting” and “sea wasp”, is considered the most poisonous marine animal on the planet. Its bite causes paralysis, cardiac arrest and leads to death within minutes. This time is barely enough for the victim to swim to the shore!

Photo: KELVIN AITKEN

Each tentacle of the sea wasp has about 500,000 needles that can inject poison into the prey. The venom of a sea wasp is enough to kill 60 people. In addition, this species of jellyfish swims at speeds up to 6.5 km/h, which is faster than most people.

Did you know?

• There are over 2,000 species of jellyfish, of which only seventy will cause harm. It is believed that thousands of species have yet to be discovered by scientists.
• Jellyfish are famous for their stinging, hanging tentacles, but not all species have them.