Question

what is the advantage of fluids filling the spaces of inner ear

Answer 1

There are large fluid-filled spaces in the inner ear. The bony tubes or labyrinths are filled with a fluid called perilymph. Within this bony labyrinth is a second series of tubes made out of delicate cellular structures called the membranous labyrinth. The fluid inside these membranous structures is called endolymph,. The different spaces of the perilymphatic and endolymphatic compartments are each interconnected by a series of duct.An important feature of the endolymphatic space is that it is completely bounded by tissues and there are no ducts or open connections between perilymph and endolymph.
The fluid's function is to register the body's movements, thus ensuring that we can keep our balance.