By the way, I think I have a way to make the role of ions
more palatable to those who have always thought water
came first. The properties of ions in water are variable.
Their energy changes enormously as the concentration
changes from 10^{-7} M for calcium to 0.2 M for
sodium. Water hardly changes concentration and in 
animals hardly changes its energy except in special
circumstances (blood circulation, movement through
the GI system). Those are important special cases;
ionic energetics and signals are universal.

The ions in the solutions form a highly compressible
fluid (i.e., number density changes). The solution itself
(which is nearly all water) is incompressible.

Biology uses the variable properties of ions as control signals
and energy sources for almost everything it does.