Most herbivores possess some evolutionary adaptation that generally protects them from carnivore attack. These adaptations include the ability to fly and run, body armor, quills and protective spines, and camouflage. In general, carnivores have higher assimilation efficiencies than herbivores. Their assimilation efficiencies range from 50 to 90 percent. Only a portion of the assimilated organic energy becomes carnivore biomass because of the metabolic energy needs of body maintenance, growth, reproduction, and locomotion.
Many food chains have no more than four or five trophic levels.
In the example above, the studied ecosystem had four. This final level is composed of the tertiary consumers who feed on the secondary consumers . The amount of biomass found in this trophic level is very small relative to the other levels. This is to be expected because of the processes, as described above, that cause continuously less energy to be available to successive consumers. Trophic pyramids have also been constructed to show the transfer of energy in caloric terms and the number of organisms found in each trophic level.