Significance in Motility?

Often in conversation, if it were relevant to point out that there is more to life on this planet than human life, the typical response would be something like, “Oh right, there’s animals, too.”

What strikes me as interesting is the fact that non-human animals are not even the most visible form of life on a daily basis (for most of us). Unless you live in a purely concrete jungle, you probably encounter grass, trees, flowers, shrubs, and a number of other organisms that could not–even in the most colloquial sense of the word–be considered “animal”. And, of course, some species of fungi are sometimes visible, as are certain bacterial strains. The diversity of the microscopic world is generally missed by the human eye, but the visible diversity of life beyond the animal kingdom is certainly obvious.

But plants don’t move around, and plants don’t have a central nervous system, and in many cases this is sufficient for casual exclusion when discussing the community of life.