Robert M Watson Jr
I was always under the impression that 'stucture' in this context mean't holding specific postures or more generally using the bones as the pimary route to sustain forces through/in the body. Consider the octopus ... no bones yet ruthlessly efficient hunter - all soft tissue.
The Octopus has muscles which it is using to create different structure. It also has teeth which have a very solid triangular structure that it uses to push through things (delicious fish!) Balloons don't have muscles or bones, yet the air pressure inside and the fabric of the balloon gives it structure. There are lot's of ways to make structure for alignments, but without structure you don't have anything really.