I used to have a lot of experience with various jellyfish. I was immersed in the gulf stream for extended periods of time while living in the Florida Keys during my youth and they were there to be encountered whether you were ready or not.
I recall encountering the Portuguese man o' war and the much more numerous bottom dwellers of the various canals — and I did indeed suffer stings every now and then.
It gave me respect where there may have been insufficient amounts previously.
Jellyfish congregate in groups which are called "blooms" or "swarms" and they are not really fish at all. No bones. No brain. Their invertebrate nature and other worldly appearance make for interesting encounters even now.
Jellyfish are plankton eaters. Some species of fish, sharks, turtles, and even people are known to dine on them. I have encountered Asian people who are skilled in maintaining them in large spectacular aquaria.
All in all the jellyfish is an interesting enigma in the marine life of the world and I try to gain knowledge of them even now.
Today is World Jellyfish Day. It happens on November 3rd and I'm not exactly sure about the observance other than scientific curiosa. I think it's important to know about things as a human being even if you actively choose not to exploit them.
Regardless of your personal level of interest in these creatures Happy World Jellyfish Day to you !