Half right for lots of critters (and apparel)- catfish, sea horse,star fish, Dog star. dogfish, deer mouse, deer fly, deerstalker, deer hound, march hare, etc. Named because of appearance, behavior, legend, quirk of language.
The chinese characters for jellyfish are 水母, which are the combined characters for water and mother. It doesn’t include the character for fish which is 魚 (ahh, I always think that looks like a little squid, or maybe even a jellyfish!). “Jelly” (as in fruit) doesn’t even figure in it, nor does anything to do with gelatinous or rubber-like properties as far as I can tell. Maybe a native chinese speaker can illuminate.
I only mention this because I ate Jellyfish in a Cantonese restaurant in Bangkok :-)
When we were on a tour near Pompeii, italy, the guide was talking about how warm the water was there along the Amalfi coast. Having experience with the jellies in warm water in both SoCal and Hawaii, I asked if they had a problem with them there. He looked puzzled at me and then finally (after a description) figured out what I was talking about. They call them Medusa’s there. Makes sense. When you find them strewn along the beach when they have died, however, they do look like clear jelly. Actually more like Jell-O.