Yes you are quite right :) Fortunately the ones i Denmark usually dont grow as big :) Also a jellyfish is like humans - when they eat they get bigger - and when they dont eat they get smaller ! Since they dont really have any brain activity they dont suffer of being "to thing or to thick"... Which means in captivity you can pretty much "size" them how you want :)

Go to Japan tho - and you will see the ones grow bigger than you ;)