15 Amazing Facts about Jellyfish

Jellyfish are ancient and fascinating sea creatures who can be found in waters all over the world. Most distinctly known for their stinging abilities, striking fear in beach dwellers and deep sea diver alike. But there is a lot more to jellies than just their treacherous tentacles and squidgy physique. 

Check out our 15 amazing facts about jellyfish to see them in a new, and perhaps more bioluminescent light. 

  • Jellyfish are old. They have been bobbing around Earth for millenia. They were here when human’s discovered fire, they have seen dinosaurs come and go, in fact scientists believe jellyfish have been wobbling through the waterways for at least 500 million years. Takes some true survival skills to jiggle around this planet for that long.
  • They can be found in almost any waterbody in the world. From oceans to ponds. Most species of jellyfish are found in salt water but there are also freshwater jellies which can be found in lakes, rivers and ponds.
  • Jellyfish are not even fish. This probably does not come as much of a surprise since they definitely do not  look like a standard fish. They are part of a group of sea animals called Cnidarians, (the C is silent) who share the unique characteristic of stinging tentacles. Other Cnidarians include certain corals, sea anemones and Portuguese man of war. Scientists now prefer to call them sea jellies.
  • Jellyfish are invertebrates, actually they lack a lot of vital features but this still does not stop them living life to its fullest. Aside from not having a backbone (or any bones for that matter), jellyfish are also missing ears, brains, hearts or blood. Their main structure consists of tentacles, bell and digestive tract. 
  • Whilst lacking some of the more common features of a functioning animal jellyfish still have plenty of tricks up their sleeve to get about in life. They do not have gills but their skin can absorb oxygen from the water allowing them to breathe. Some species also use sensors in their skin that pick up light, helping them navigate the oceans. 
  • Jellies get about by propelling themselves through the water by contracting and relaxing their bells, this is efficient in calm seas but if the current kicks up then the jellies will just go with it. Sea animals which drift through the ocean are known as zooplankton. 
  • Jellyfish are made of 95% water, there is only 5% of jelly matter separating them from the sea. This often means that if a jellyfish is washed up on land it will almost completely evaporate. 

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  • Sea jellies are swimming in species. From translucent to transparent, currently over 2000 species in all different colors, shapes and sizes. Due to the relatively unexplored nature of our deep oceans it is estimated there could be up to 300,000 species in total that are yet to be discovered.
  • The largest jellyfish species is the Lion’s Mane which can reach up to 7ft/2.3m wide with tentacles reaching 121ft/37m long. The smallest jellyfish is the Irukandji box jellyfish averaging a minute 1mm wide, its tentacles can still reach 3.2ft/1m in length. Despite its size it is still capable of producing a sting fatal to humans. 
  • Jellyfish still offer some nutritious value to predators. You would think with a jellyfish’s lack of, well, everything they would not be worth consuming but they are still eaten by other sea animals and birds. A recent study discovered that jellyfish can provide important fatty acids when enough are consumed. They definitely do not seem like the most appealing snack but animals such as turtles, whales, sea birds and sunfish are their common predators.
  • Jellyfish themselves are passive predators, they are carnivores but rather than hunt for their meals they wait for creatures to get caught in their tentacles. Their sting will paralyze fish and the sea jellies suck their prey up into their mouth where they will digest any nutrients and then spit out any waste.

More of a seahorse lover? We have got you covered: 15 Fun Facts About Seahorses.

  • Jellyfish also use their tentacles to protect themselves, some larger sea animals may not get caught up in jellyfish tentacles but they will definitely feel the stingy sensation which can deter them from attacking. Another great protective feature is a jellyfish’s translucent appearance, this makes it harder for predators to spot them.
  • Most jellyfish only enjoy one rotation around the sun, there is only one species which outlives its year long expiry date. The immortal jellyfish is very deserving of its name, this particular jellyfish is able to regress back to infancy in order to heal damaged cells. It can then start its life cycle all over again and continually repeat this cycle allowing it to live indefinitely. It is the only known animal who is capable of this. 
  • Jellyfish have helped scientists earn nobel prizes. The crystal jelly will start to glow green if it feels threatened. Scientists were able to identify the protein which causes the jelly to illuminate and harnessed it as a way to track cancer cells and Alzheimer’s so they can better understand these diseases. These scientists were awarded nobel prizes for their work.
  • Jellyfish love to meet up, a group of jellyfish is known as swarm, smack or bloom. It is believed they swarm so they can mate but this reproduction ritual can be quite alarming as its scale can vary from one cubic meter up to 100 sq miles. This can lead to entire beaches being closed to avoid humans being stung. 

5 Of Our Favorite Jellyfish Species

1.Australian Box Jellyfish 

Jellyfish are the most venomous marine animal in the world and Box jellyfish are number one for fatal stings. There are several different species of box jellyfish but a sting from the Australian Box jelly can lead to cardiac arrest, paralysis and death within minutes. These deadly creatures can be found in waters on the Australian coast and southeast asia, if you are unfortunate enough to see one retreat as soon as possible. 

Did you know that some birds freedive? Check it out: Feathered Freedivers: 8 Birds That Can Dive Underwater.

2. Lion’s Mane Jellyfish

We have to mention Lion’s Mane jellyfish because they are massive, in fact a swarm once caused a fishing boat to capsize as its nets could not hold the weight. These jellies enjoy cooler waters such as the North Pacific Ocean and the Arctic. They don’t venture further than 65 ft deep so it is possible to spot one on a dive. 

3. Bloody-Belly Comb Jellyfish 

You are unlikely to spot these rogue jellyfish as they hang out at depths over 1000 ft but if you did bump into one you would know it. This jelly has a bright red stomach and due to its translucent bell it makes the jelly appear in tones of red, black and sometimes purple. In the deep ocean red is invisible making it easy for the jelly to hide from predators. This sci-fi super star in-waiting lurks in oceans surrounding Japan, Canada and Southern California. 

4. Fried Egg Jellyfish

No award for why this jellyfish has its name. This particular jelly has a yellow circle in the center of its bell similar to a fried egg. Their tentacles can be yellow and purple and look quite similar to scrambled eggs. These particular jellies often hang out in shallow waters, you will only be able to see them during warm months as once it gets cold they die.

Need more juicy marine life content? Here you go: 8 of the Fastest Marine Animals (divessi.com)

5. Upside-down Jellyfish

These endangered species are extremely unique, as you may have guessed they live life upside-down with their tentacles facing the sun. They do this to create energy using their algae tissue for photosynthesis. Rather than stinging prey with their tentacles they produce a mucus with stinging properties. It is not deadly to humans but you will feel it and mucus is always grosse. These jellies can be found around the coast of Australia and can be mistaken for flowers so watch out. 

Which would you most like to see while scuba diving?