25 Jellyfish Facts to Indulge Your Curiosity

Jellyfish are mysterious and very beautiful inhabitants of the seas and oceans of the planet. And they can grow longer than blue whales.

Did you know that jellyfish are considered heartless, boneless, brainless, and eyeless marine creatures? 

Yes, that is true. Although jellyfish are missing all those essential organs, they got a lot of things to show off. Therefore, we gathered 25 jellyfish facts to indulge your curiosity.

1. Jellyfish are one of the most ancient inhabitants of the planet, which have not yet been fully studied. It is because some of them live at a depth of up to 6 miles (10 thousand meters).

2. Jellyfish are one of the oldest forms of life on the planet. They appeared about 600 million years ago, long before dinosaurs, crocodiles, and sharks.

3. Jellyfish live in all the oceans of the Earth. It is hard to estimate how many jellyfish exist in the wold oceans, but scientists estimated that there are 2,000 species of jellyfish. Although most of them sting, the stings of some species are harmless.

4. Jellyfish Turritopsis Nutricula is the only living creature in the world that is immortal. It can “rejuvenate” its body. During adulthood, the jellyfish turns back into a polyp, forming a new colony that continues to produce young jellyfish. Theoretically, this process can continue indefinitely. The death of Turritopsis Nutricula is only possible if they become prey for predators.

5. Cyanea Capillata is the largest jellyfish in the world. It is also known as the lion’s mane jellyfish. The diameter of its dome can reach 8.2 ft. (2.5 m). And they have over 800 tentacles that can reach the length up to 120 ft. (36.5 m). Lion’s mane jellyfish can grow longer than a blue whale, which has a length of 98 ft (30 m.). 

6. In the Middle Ages, people used jellyfish for medical purposes. For instance, early doctors made drugs extracting venom from the tentacles of jellyfish. Supposedly, those substances helped to regulate blood pressure, and treat lung diseases. 

7. Chironex fleckeri known as a sea wasp is the most dangerous jellyfish. Most people are afraid of poisonous spiders and rattlesnakes, but the most dangerous animal on the planet for humans can be a type of jellyfish-a sea wasp. A slight touch of the sea wasp’s tentacles causes excruciating pain, and closer contact with these jellyfish can kill an adult in a couple of minutes. 

8. The tentacles of a poisonous jellyfish remain dangerous for a long time even after the jellyfish dies. In other words, dead jellyfish can sting you since its toxins remains in its body for while. That means you need to avoid touching dead jellyfish.

9. Residents of Japan and China have come up with methods of eating poisonous jellyfish. Once caught, they boil the jellyfish and dry them properly by adding salt. In some cases, people ground the dried jellyfish into a powder form to make jelly and tofu.

10. Jellyfish are invertebrates. Meaning they do not have a backbone like mollusks and anthropods. In fact, they have no bones at all. Also, jellyfish do not have a central nervous, cardiovascular, or respiratory system.

11. Their almost transparent bodies consist of only three layers of the outer epidermis, the middle mesoglea, and the inner gastro derma. The water makes up 95-98 % of the total volume of jellyfish, where the water makes up 60% of the human body.

12. Like many animals, the life cycle of jellyfish begins with eggs that are fertilized by males. After that, things get a little more complicated. Free-floating planula (larva) emerges from the egg that looks like a giant infusoria slipper.

13. Almost all types of jellyfish begin their life cycle as polyps. Only in the second stage, they turn into jellyfish.

14. Jellyfish get their oxygen from water. More specifically, the cells of its out layer (epidermis) absorb oxygen and carry it to the mesoglea layer.

15. Jellyfish do not have lungs. Nevertheless, they breathe with the entire surface of the body.

16. Some jellyfish have eyes. In particular, cubomeduses have a couple of dozen light-sensitive cells in the form of an eye patch. Unlike other marine invertebrates, some have cornea, lenses, and retina. These complex eyes are arranged in pairs around the circumference of the bell (one pointing up and the other down, providing a 360-degree view).

17. Scientists do not give a definite answer to the question of how long jellyfish live. Many agree that the life cycle of these animals is short and the life expectancy of most species is from two to six months. However, according to National Geographic, jellyfish are immortal since they can convert their body back to polyp form when their body needs rejuvenation.

18. When it comes down to climate, there are two groups of jellyfish: heat-loving and cold-loving jellyfish. For example, heat-loving jellyfish live only near the surface of the water. And those who prefer cold water live only on the bottom of the ocean.

19. Jellyfish are solitary animals because they do not communicate with each other in any way. However, they form colonies thanks to the currents that bring them together.

20. These creatures got the name medusa in the middle of the XVIII century when Swedish naturalist Karl Linney noticed the similarity of jellyfish with the mythical head of the Gorgon Medusa.

21. Jellyfish are symmetrical creatures; they don’t have a right or left side.

22. The digestive system of jellyfish is very simple: it has only one opening (mouth), through which food (fish, plankton) enters and waste is thrown out of it.

23. Jellyfish belong to the Cnidaria type, like corals, anemones, and hydrazones.

24. Aurelia jellyfish is found in the black sea, has a cap up to 16 inches (40 cm). NASA took the jellyfish into space for experimental purposes. Interestingly, the experiment turned out to be successful-the animals perfectly existed and multiplied in weightlessness, but died when they returned to earth. They were not used to gravity.

25. The first Museum of jellyfish appeared in Ukraine, the main exhibits of which are real jellyfish. The collection includes several dozen species, each of which surprises with its beauty, grace, and grandeur.

By Arslan Batyrovich

Founder of
Writer, Researcher, Fact-finder, and All-in-one
Loves nature, Likes history, and Adores anything interesting
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