Jellyfish facts.

Weird But True: Jellyfish Facts

Ever wondered how Jellyfish reproduce? Or how many anuses a sea wasp has? Well, probably not, but you can find out here anyway.


  • The Box jellyfish has 64 anuses.
  • The Box jellyfish also has 24 eyes, but despite this, it can only see in a blurry fashion.
  • Jellyfish do not have a brain, respiratory system, circulatory system, or indeed an excretory system. Because of this, the jellyfish’s ‘mouth’ is also used for waste expulsion.


  • Jellyfish NEVER stop growing.
  • Jellyfish are 95% water, and some types, nearly 98%.
  • Jellyfish are not actually classified as ‘fish’, some people prefer to refer to them as ‘sea jellies’. They do not have gills (or lungs)
  • To “swim”, jellyfish shoot jets of water that propel them forwards. However, most jellyfishes movements are limited to up and down, they are carried along by the tide.
  • Jellyfish are actually older than dinosaurs (well, as a species, not individually)
  • To breathe, Jellyfish absorb oxygen through their membrane-like skin.
  • Jellyfish are EVIL (not strictly true, but they look it)


  • Though jellyfish are most commonly as large as a big plate, one type of jellyfish in the Arctic sea can be up to 7 ft in diameter, and the tentacles can also be up to 120 feet long!
  • The biggest jellyfish can be up to 2 and a half meters wide, and it’s tentacles can be half as long as a standard football pitch.
  • One of the biggest jellyfish is called the lion’s mane.


Yup, it’s what you sick people out there have been wanting… probably…

  • During different parts of its life, the jelly fish is able to reproduce sexually AND asexually:
  • Jellyfish can be either Male, or Female, and each sex develops their sperm or eggs in a special pouch on the inside of the jellyfish.
  • They then (technically) throw up the sperm/eggs, as it passes through the stomach, and then the mouth.
  • Some of the eggs stick to the mouth of the female jellyfish, and these are the ones that are fertilized.
  • The embryo develops into, not a baby jellyfish, but a planula, and from there it begins a long journey, being carried by ocean currents. It eventually evolves into a polyp, which can then create more polyp via a process called budding. Eventually, grooves appear on the polyp, and it breaks open, revealing lots of disc-like saucers, which are in fact, baby jellyfish. So one egg fertilized makes a lot more than one baby jellyfish!


  • There is a type of jellyfish that lies upside-down on the seabed near coastlines (probably just waiting for a wader or some toddler to come and step on them…) that is plant-like in the way that it collects energy from the sun’s light.
  • The Box Jellyfish, also named the ‘SEA WASP’ is the most poisonous jellyfish, and it’s sting can kill in 3 minutes… and it can move at almost 2 meters per second. If stung, the odds of getting back to the shore, or even SURVIVING are almost 0.
  • Jellyfish kill more people than sharks (and for that matter, being hit on the head with a falling coconut)
  • The jellyfish population can be decreased by particularly rainy season, because they prefer salt water.
  • The amount of venom in a Box Jellyfish could kill 60 people.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s