World Jellyfish Day

1. Jellyfish are thought to have been living in the seas and oceans for over 500 million years. We know this because scientists have found fossils of jellyfish from around 505 million years ago!

2. We know about 2000 species of jellyfish but it is likely there are more that haven’t been found yet! The largest species of jellyfish is called the Lion’s Mane Jellyfish. It has a width of 6 feet (about the same as a tall man) and tentacles that are double that or even longer!

3. Despite their name jellyfish are not fish! They are a type of invertebrate and have no backbone. Jellyfish also have no brain, no heart, no blood and no eyes either!

4. Jellyfish are 95% water! They are made of three main parts, the bell or umbrella which they use for moving through the water, long stinging tentacles which they use for defence and thicker frilled oral arms that they use to move prey to its mouth, which is under the bell.

5. Jellyfish have a simple nervous system that allows them to react to their environment and helps them sense touch, temperature, and smell. 

6. Jellyfish are carnivores that eat small marine animals, such as plankton, small crustaceans and fish. Some species will even eaten other jellyfish. They use their stinging tentacles to capture and paralyze their prey. They don’t actively hunt down their food, instead they just wait for prey to come in contact with their tentacles!

7. Jellyfish sting their prey (and anything else that gets in their way) using their tentacles. These are covered in tiny stingers filled with a type of venom.

8. Some jellyfish are clear, but others are brightly coloured. Jellyfish can be pink, purple, yellow, orange, blue and red. They can also be bioluminescent too, which means they produce their own light!

9. Humans can be hurt by some, but not all jellyfish stings. How bad the sting is depends on the species, with some having very mild stings while others causing serious harm. Out of over 2000 species only about 70 could hurt a human.

10. There is one jellyfish that has the nickname the Immortal Jellyfish. In theory, if it managed to avoid getting hurt or eaten, it can reverse its life cycle to a polyp stage, restarting its life, and potentially live forever!