Commonality
Most soft-bodied animals are small, but they do make up the majority of the animal biomass. If we were to weigh up all animals on Earth with hard parts against soft-bodied ones, estimates indicate that the biomass of soft-bodied animals would be at least twice that of animals with hard parts, quite possibly much larger. Particularly the roundworms are extremely numerous. The nematodologist Nathan Cobb described the ubiquitous presence of nematodes on Earth as follows:
"In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites."
Read more about this topic: Soft-bodied Organisms