For me at least, Murchie's book was a revelation. I was ignorant of the possibilities he discusses of "movement without muscles, sight without eyes, hearing without ears, smelling without a nose, thirst quenching without drinking, eating without a mouth, digestion without a stomach or excretion, reproduction without sex, thinking without a brain and life without rest, sleep or death."
I don't now feel we are in the position to be drawing philosophical lines around what is the mind, the self, etc, when so much is still unknown.
OK, I'll bite. What moves "without muscles"? Single-celled organisms do, for sure. But the actin-myosin ratchet is a key part of the eukaryotic cytoskeleton that handles movement. The bacterial machinery is more distantly related, but still analogous. Even viruses use analogous machinery.
Greg Egan's Orthogonal trilogy features some amazing single celled organisms :)
> Below the world of worms and burrowing snails we may consider microscopic creatures like the ameba, who oozes along by pushing out lobes or ruffles of his single cell protoplasm and just flowing into them. His locomotion system (often called "ruffling") was only recently elucidated. It works in each lobe something like an advancing jet of jelly that spreads like the crown of a fountain at its forward end, turning outward in all directions, then back in the form of a surrounding cuff that condenses into a sleeve stiff enough to grip the ground until, turning once more in the rear, it liquefies and pours inward through the center. Biologists used to think that a muscle-like squeezing of the sleeve's protoplasm at the hind end pushed the jelly forward like toothpaste out of its tube, but newer evidence strongly indicates that it is the continuous contraction of the jelly at the forward "fountain zone" (where it turns and stiffens) that literally pulls the central stream steadily ahead. So the consensus of opinion now is that the ameba advances somewhat as does an oriental king, by having his carpet swiftly unrolled before him as he walks, then as nimbly rerolled behind for further unrolling ahead.
> Another method of microbe locomotion, up to several hundred times faster but still slow in human terms, is that of flagella or bacilli with tails. Some of them propel themselves by a recently discovered swivel motion, each flagellum lash rotating freely about its axis like the rigid propeller of a small airplane, generally pulling from the front end and changing course by reversing the direction of rotation. So far as I know, this is the only true wheel motion produced by nature before man invented the wheel about 3500 B.C. and it is powered by the equivalent of a reversible microscopic engine, something technological man has not learned how to make even today.
> A different system again is that adopted by ciliates, common in mud and ponds, whose bodies are covered with thousands of rapidly waving hairs called cilia. Up to 20 times a second each cilium (one thousandth of an inch long) makes its stroke, much like a human swimmer's arm action, first reaching gently forward edgewise for minimum resistance, then sweeping rigidly backward broadside for maximum resistance, the beats coordinated in beautiful rhythmic waves of succession, like pistons in an engine or stalks of wheat blowing in the wind. Even some visible animals use ciliated drive, notably two kinds of comb jellyfish the sizes of a gooseberry and a walnut, and often called respectively the "sea gooseberry" and "sea walnut," each of which has eight longitudinal belts of cilia (coordinated by a special balance organ) that steer and propel it like a spherical Caterpillar tractor.
For what it's worth, the immune system and brain develop more or less concurrently. And have mechanistic similarities at the biochemical level.