an ecosystem contains large numbers of living organisms
earth has not many_different_living_organisms aquatic_organism is living_organism. population is group_of_living_organisms. large_living_organisms_tend_to has not more_mass_than_smaller_ones large_living_organisms_tend_to has more_mass_than_smaller_ones biome is ecosystem. multicellular_organism is not living_organism. multicellular_organism is living_organism. microorganism is living_organism. earth has many_different_living_organisms