Jelly fishes aren't fishes truly but they live in the ocean and they are a fascinating creature. They are made up of 95% water, so we could assume that they are more water than animals. Humans are also made up of lots of water up to 60% but we aren't basically water unlike jellyfishes. Jellyfishes do not have any brain, heart or any other organ that we can recognize in animals. Jellyfishes are invertebrates with no bones, funny enough, Jelly fishes move in all direction making it look like they don't know their direction but they have been for over 500 million years.
When jelly fishes pulse their bells, they do so to help them swim around as well as swirl food into their tentacles and oral arms. When they pulsate, their stinging cells in their tentacles release venom that would stab their prey thereby paralyzing them before consuming them. Some Jellyfishes in the class cyphazoa possess oral arms. Depending on the type of jellyfish, the bells can have different shapes and the jellyfish bell holds the basic digestive and nervous system.
Another concern will be that since it doesn't have any organ that we can see, then how does it breath. To solve this, jellyfishes uses the process of diffusion to absorb oxygen through their thin body walls thereby allowing them to survive without any respiratory organ. In fact, jellyfishes function both as predators and prey, as predators they feed on smaller organisms like planktons, small fishes, they also feed on themselves. While being a predator to the small animals, they are food for larger animals like sea turtles and other larger animals.
The type of jellyfish available can vary depending on the shape, size, and colors. The jellyfishes include Moon Jellyfish which have a translucent saucer shaped bell. It is found in temperate and tropical oceans and they often move in large numbers (Swarm of jellyfishes). Another type of jellyfish is the Lion's mane jellyfish and it is the largest jellyfish that we know for now since we discover new things everyday. The Lion's mane jellyfish is found in cold waters of oceans like in the arctic, or northern Atlantic and pacific ocean.
Remember I mentioned that they possess venom to paralyze their prey? It is in that light that I must mention that the box jellyfish is one of the most venomous marine creature in the ocean. This jellyfish as the name implies looks like a box as it is cube shaped with potent venom in its tentacles that can be fatal to humans. It is found the Indian and Pacific ocean.
While some are cube-like, others are like cannonballs and so referred to as cannonball jellyfish. Found in the ocean of the United States and the Caribbean. It doesn't have harmful sting to humans, but its sting can hurt small fishes. Jellyfishes are interesting creature and we cannot deny their importance in the ecosystem.
READ MORE
https://www.nhm.ac.uk/discover/what-is-a-jellyfish.html
https://europe.oceana.org/feature-about-jellyfish-0/
https://oceanservice.noaa.gov/facts/jellyfish.html
https://ioa.factsanddetails.com/article/entry-318.html
https://www.nhs.uk/conditions/jellyfish-and-other-sea-creature-stings/
