Very good shots! I just ordered a Sigma 105 for my D300 from 47st Photo, but it was sent "signature required", so I had to have UPS hold it until Friday when I have the day off - Darn!
Just my personal preference; with colonial inverts, unless I'm going for an "artsy" look, (like your image #6) I try to include the whole critter with enough substrate so that non-aquarium people can get some frame of reference as to the subject matter.
Jay