Luckily, not everyone lets himself be restrained in this way, and that is why I would like to draw your attention to the work of thomastapir, whose work can be seen at deviantART. Like me, he likes locomotion and biomechanics, and he has produced some truly original creatures. I will only focus on one of his aliens here, but his dinosaurs and mythical beasts are well worth an visit. I will very likely revisit his page one day to discuss the 'Moebius inside out animal'.
|Click to enlarge; copyright thomastapir|
I should perhaps jump right in with the Xenohox gazelle, as starting there will give you the full sense of wonder, but it would need a lot of explaining at once. Starting with this forerunner, here in its original place, has the advantage that its shape can be taken in fairly easily. Now this shape is new. One way to look at body shapes is to smooth the surface of animals until the shape cannot be reduced further, revealing its topology. Limbs, as simple protrusions, disappear, and our own vertebrate shape reduces to a blob with a hole through it, i.e. a torus: our digestive tract forms the hole. Jellyfish have no such hole, and can be reduced to a blob, or probably even a sheet. Thomastapir's animal represents three half tori mashed together.
|Click to enlarge; copyright Gert van Dijk|
|Click to enlarge; copyright thomastapir|
The animal above, the 'Xenohox Gazelle', has the same topology as the triphidian. To develop it, we can pull at the surface to produce extrusions, in the same way we can pull at a single torus to sculpt a human or a millipede. The result of this sculpting are three strong limbs.
You will probably need time to work out how this animal is built, and understanding how it moves will take more study. Thomastapir's remarks on his deviantART page explain how it works. He has chosen to keep the triradial anatomy fully intact. Others -well, me at any rate, see here and here- might have decided to let two of the half tori develop into weight-bearing structures, freeing the other one for other uses such as manipulation. Thomas kept all three as equally functional locomotor limbs, which inevitably leads to the conclusion that the animal must turn along its body axis to bring each limb towards the floor in turn. That is very interesting but also very complex. You will need a good ability to visualise movement in your mind's eye to understand it. This is the task: the animal is running across your imaginary field of vision, its body spinning like a screw as it does so. Each leg rotates along with the body, and when it is pointed downward, it also moves backwards pushing at the ground. When it moves up again it also moves forward. If you manage to visualise that, add the two other legs, of course with the proper phase difference. Got it?
If you did not, never mind, as I prepared an animation to help you see how it works. I am fairly pleased how it turned out, although it seems to move more ponderously than the name 'gazelle' suggests. Perhaps I stumbled along the analogue of a heavy eland antelope instead of a slightly built gazelle.
I do see one problem with this way of movement, and that is that it adds complexity to sensing the world around you. The eyes turn with the animal, so the visual field continually turns around as well. That cannot help vision one bit. This is very similar to the problem I encountered in 'cernuation'. There was a solution though: the head would turn against the movement keeping the eyes still (of course, after one turn the head would have to snap back to allow a new counter turn). When I mentioned the vision problem to thomastapir he answered the following:
"On the complication of vision due to rapid rotation about the long axis--it could be a matter of, let's say it has three eyes, that each eye takes a sort of "snapshot" at specific point in its motion cycle--say, when the given eye reaches the top of its rotation. So then a composite or gestalt image is built up sequentially from those single snapshot images, almost like a flip book or film strip. The rate of rotation is rapid enough that it should create a fairly smooth, uninterrupted stream of visual information. And certainly it could keep one or more eyes continuously open when it's motionless or walking slowly."
That would probably work, but is not ideal either, as visual information would be lost some of the time.