Why there is no 'walking with tentacles'... (4)

So the 'Walking Tentacle, Mark II' developed last time has a stack of elements able to withstand compression and still has considerable amount of freedom, with its many ball-and socket joints. In fact, I was tempted to elevate it to the level of a 'Working Solution' and to keep it in the Furaha universe. There are several things it cannot do that a completely muscular tentacle can do, and that is to lengthen or to shorten at will. It also still takes lots of muscle force just to keep it in place.

There are some interesting refinements to be considered. One thing I came up with is that the surface of the joints is now completely smooth, not obstructing movement in any way. But suppose that the surface could somehow be made to become less smooth if needed. Perhaps with small elements under the surface that can be raised to make the surface coarse-grained. If you do that on both sides of a joint's surface, the friction will become much larger, so the joint would need less muscle force to stay in place. That would be the Mark IIb...

But a much more likely development would be to reduce the number of movable elements. Simply lengthening the compressive elements inside the tentacle would solve many problems: there are fewer areas of motion, hence fewer places where muscle force is needed. The concentric muscle cylinders can go, as they are replaced by muscles spanning one or two joints.

But consider the nature of this Mark III 'Walking Tentacle' looks like: it is a series of elements made of strong material able to withstand compressive forces, and movement is effected by muscles pulling at these elements, causing them to rotate at some places only: yes, the Mark III 'Walking Tentacle' is a leg, and that's why there's no 'Walking with Tentacles': they evolved into legs...

Here it is, with just two muscles (click to enlarge)