These amazing animals are very strange and like no other in the world. They are made up of mostly water and take on a jellylike consistency which is where they get the name jellyfish despite not being a fish at all and in fact being a type of invertabrate.
Jelly fish do not have brains and instead are just responsive creatures with a nervous system that simply responds to stimuli in the world around them. Most of these responses come from the tentacles for which jelly fish are famous, as these tentacles allow them to touch and feel, smell and obtain other information about the world around them. Jellyfish, or stingers as they are know in some parts, are feared by many humans for these tentacles as tehy contain dangerous weapons that sting their prey (or even the unlucky swimmer). While some can cause severe problems for humans, and even death, most jellyfish stings result only in discomfort and pain for a while for humans. Fish however, are not so fortunate and make up the main diet for jellyfish.
The life of a jellyfish is a short but incredible one. They often only live a few months depending on which type they are, and even those that live longer will rarely reach their first birthday with most only surviving for upto six months.
Jellyfish breed in a strange manner without actually having contact with one another. Instead reproduction occurs by sperm swimming through the water from the male to the female and creating the baby that way. When born the jellyfish are not in the form of what we might think a jellyfish to be. Instead they create almost plant like things that attach to the ground underwater and grow that way. Then after a few weeks they divide and break off from their plant like status to become more jellyfish like and swim around.
The adult form is the most known and this is what gives them the name jellyfish.
They are amazing for the way they live their short lives and have not evolved much over the years despite being around for millions of years.