In the human world, hydraulic-fluid power offers competition to both electrical and mechanical power. Fluids are used in vehicle braking and transmission systems, in mass-production units, and even structurally, as in large rockets, whose thin skins are given more 'body' by internal fluid pressure.
But, as so often, Nature got there first. The structural role of fluids can be seen in a cut flower, which droops if left without water. This is because its stem is composed of highly flexible cellulose fibres stressed by the internal pressure of sap. When this dries out, the pressure lessens and the flower wilts. The same effect can be seen on the foliage of trees after prolonged drought.