Zoologists Warn: 6 Dangerous Jellyfish You Should Avoid Touching


Zoologists Warn: 6 Dangerous Jellyfish You Should Avoid Touching



With summer coming many people are planning a long-desired vacation and dreaming of a warm sea. Perhaps, the most unpleasant thing that can happen on vacation, except for bad weather, is the influx of jellyfish. Some people ignore them and feel quite comfortable in the water, others prefer to avoid contact with them for various reasons (from disgust to fear). And they are right, as some of the species are a threat to health and even life – an expert zoologist will tell about them.

The main danger of an encounter with a jellyfish is not only a burn which is surely unpleasant but also that after a sting a person may develop a strong allergic reaction to toxins in her numerous stinging cells.


Dangerous species of jellyfish

Most of the people have met these creatures at least once in life. As a rule, their influx is seasonal and occurs when the water temperature reaches 29-30 degrees. Usually, it is non-dangerous species that swim up to the shore, however, every year due to their population increase it becomes more frequent when the flow brings especially venomous jellyfish, which you need to learn to recognize.

1. The sea wasp (Chironex fleckeri)

The sea wasp is one of the most dangerous among these representatives of fauna. Most often it is found in the tropical seas of Australia and Oceania. This predator is unique in its own way. Unlike fellow jellyfish unable to move fast, this one is quite agile. Moreover, while hunting, the sea wasp uses sight not merely reacting to light as other types of jellyfish do, and decides where to swim.

You can recognize the sea wasp by 4 bundles of tentacles with their length reaching up to 5 feet. One individual stores enough venom to kill 50 people.

2. Irukandji (Carukia barnesi)

This miniature jellyfish, reaching only 0,7 inches in diameter, has dangerous tentacles reaching 14 inches in length. Irukandji looks pretty cute, but in fact, it is one of the most venomous animals on the planet. It dwells mainly near the coasts of Australia and Oceania, where, despite warning signs on the beaches, 20-25 people suffer from it every year.

3. The Portuguese man-of-war (Physalia physalis)

This beautiful marine creature only looks like a jellyfish. In fact, the Portuguese man-of-war is a whole colony of organisms. A luxurious blue or purple dome of a relatively small diameter (4 – 11 inches) hides several meters of venomous tentacles.

The Portuguese man-of-war, unlike other types of jellyfish, consists of four types of polyps, each of which has its own function:

  1. A gas bladder – is a part of the colony visible above the water, it doesn’t let it drown.
  2. Dactylozooids – are polyps responsible for hunting and defense of the Portuguese man-of-war. They are often as long as 33 feet. These tentacles are covered in venom deadly for humans.
  3. Gastrozooids – are feeding polyps.
  4. Gonozooids – are reproductive polyps.

They are found in tropical regions and they generally move in groups of up to 100 colonies. They are also frequently washed into the waters of the temperate zone.

4. Clinging jellyfish (Gonionemus vertens)

This relatively small jellyfish with a dome of up to 1,5 inches in diameter is easy to distinguish by its red-brown cross formed by colored internal organs, which is clearly visible on its body. This species of marine life has many tentacles – there can be as many as 80. In addition, they can stretch far. Its sting is very painful, but, fortunately, not lethal. Clinging jellyfish live in the Northern part of the Pacific Ocean – in the coastal waters of China and California.

5. Nomura’s jellyfish (Nemopilema nomurai)

Nomura’s jellyfish is a jellyfish giant. It reaches 6,5 feet in diameter and weighs over 440 pounds. Nomura’s jellyfish are found in the Far Eastern seas near the coast of China, Japan, Korea, and Russia. Often, these jellyfish get caught into fishing nets and sting fishermen who are trying to untangle them. There have been lethal cases.

6. Sea lice (the larvae of the thimble jellyfish)

The larvae of this species of jellyfish are called "sea lice", as they are not larger than a rice seed in size. They often get in between the body and the swimsuit, and sting people when compressed. They are found on popular American beaches, tropical and subtropical the western Atlantic Ocean. Their venom is not fatal, but the stings are very painful.

What should you do if you get stung by a jellyfish?

Many types of jellyfish are able to immobilize their victims and even kill them with the help of cage cells. These cells contain capsules with venom and a sharp spear extending from them. When a person touches a sensitive hair on the surface of this cell, it stings. The sharp tip of the spear breaks off releasing the venom.

Symptoms of burns:

  • tingling;
  • dizziness;
  • headache;
  • nausea;
  • vomiting;
  • fever;
  • cardiac arrhythmia.


Seek immediate medical help when you experience:

  • pain or cramps in the abdomen;
  • stomach upset;
  • rattling when breathing;
  • weakness;
  • urticaria fever;
  • nasal congestion;
  • racing heart;
  • impaired speech articulation.


First Aid

  1. Wipe the place of the sting with salt water. Important: you shouldn’t use fresh water, as it can release the remaining poison.
  2. Treat the affected area with shaving cream or a mixture of flour and water. Then rub it with a flat hard object to remove the stinging cells from the skin.
  3. Have the affected area covered with a piece of cloth soaked in an aqueous solution of vinegar (1:1) for 30 minutes.
  4. Treat the sting area with an analgesic.


Did you know?

  1. The population of these beautiful and often dangerous creatures is increasing due to rising water temperatures, pollution, and water blooming.
  2. Jellyfish have eyes sensitive to light, although not all of their species use eyesight.
  3. Primitive organs of equilibrium help them to stay on the surface of the water. Jellyfish never go down to the bottom, because it is lethal for them.
  4. They have mouths, which are surrounded by tentacles and lead directly to the intestines.
  5. Jellyfish are predators. They feed on zooplankton and fish larvae, although some marine inhabitants are not sensitive to their venom and can even coexist under the reliable protection of the dome.
  6. These creatures are 98% composed of water.
  7. Jellyfish can’t move quickly – they move with the flow.

Not only are these marine inhabitants very beautiful and graceful, many of them are also dangerous. Do not fall for a misleading opinion that only harmless jellyfish swim up to the shores, try not to contact them, as there may be venomous ones among them.

This article is solely for informational purposes. Do not self-diagnose or self-medicate, and in all cases consult a certified healthcare professional before using any information presented in the article. The editorial board does not guarantee any results and does not bear any responsibility for any harm that may result from using the information provided in the article.

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