The diver I do some webwork for suggests not considering them because not only do they die off quickly, nothing else lives in the areas of the reef that they populate. He has done a lot of hands on research (some with Martin Moe) on the dieing reefs in the keys and I trust his evaluation. If you should want to experiment (they are not endangered or even close), please consider a species only tank and start a journal for the rest of us that are curious ;>).
They need to be in tanks with no corners, and I read an article in either Tropical Fish Hobbyist or Aquarium Fish International about how difficult they are. There's a big jelly exhibit at my local aquarium, they have a whole breeding lab set-up for them, very interesting stuff.