Because the first one wasn't big enough.
But I feel this one is harsh in the highlights.
I am not sure it is because all colours is so saturated and the high light is too much white.
Secondly I find the top a little pillowshaded, but I am not really sure about it.

Any advices?

I was inspired of Red Lion Mane Jellyfish, they looks like gasplanets, Like this:

But I think might make it look more transparent at body.
I already have three tentacle, they are not really visible. But more thin transperant wirelike tentacles would be nightmare for me, because the lack of readability.

I initially saw the top of a carrot, then with Xevil's comment I can kind of see the planet too (although it is not spherical) A jellyfish is not a jellyfish without it's tentacles I'm afraid so this won't read jellyfish until you can see the whole creature.