A few species of plants adopted to a life on land, beginning in Late Silurian or Early Devonian. Rapid motility requires development of hard parts to which muscles can be attached. Sessile forms could increase in size with supporting skeletons. Mobile organisms need attachment sites for strong muscles. Energy transfer between tropic levels is not very efficient.
Energy is lost by respiration, waste, decomposition.
It is generally assumed that similar efficiencies occurred in ancient oceans. However, in the Cambrian, only primary consumers and a few predators existed, therefore the marine trophic structure was very simple. Early Paleozoic Organisms 1. Some soft-bodied organisms with armor plates. Probably represents about 10 Ma interval.