theres a thread showing aquaria graphics by david in open topic which should help you, look for it, its not that old.
I've seen it some time ago.
My sprite is diferent. i`m a bit a afraid i gave it to much depth.
For what i've seen by now, sprites that are prepared for bone movement are being simplefy shaped and less depth. Altho i will draw another one which will be prepered for cutting for the animations i`m not shure is the style good for bone anim.