With the exception of the predators, all these organisms feed directly from plant material (saprobes).

There, organisms feed on them and mix the organic material with the upper soil layers; these added organic compounds become part of the soil formation process.

But these trophic levels are not always simple integers, because organisms often feed at more than one trophic level.

Higher organisms then feed on the fungi and bacteria in a chain of life.

As their behavioral repertory expanded, organisms could feed more actively than ever before.

However, it appears that organisms did not feed upon the sediment itself until after the Cambrian.

The new organism outcompeted other algae for nutrients or fed on a different nutrient mix created by the abnormal conditions.

Monophagous organisms feed exclusively or nearly so on a single other species.

These organisms feed off of chemosynthetic bacteria, which use the super heated water and chemicals from the hydrothermal vents to create energy in place of photosynthesis.

Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web.