Do tổng khối lượng toàn phần của một hệ vật lý kín là bảo toàn (không thay đổi theo thời gian), theo định nghĩa, tổng năng lượng của hệ vật lý kín cũng bảo toàn. Xem thêm bảo toàn khối lượng. | 50 energy a beginner s guide most transfer ends after just two steps with secondary consumers ungulates antelopes gazelles impalas wildebeest eat grass felids leopards cheetahs lions and canids wild dogs hyenas eat ungulates and decomposers feed on their remains and anything else they can break down with their enzymes. No fierce carnivores can be found feeding at the sixth level from the Sun. In tropical rainforests with a greater much more varied standing phytomass and a greater variety of heterotrophs three levels are common and five are possible fungi feed on plants arboreal invertebrates feed on fungi frogs feed on invertebrates snakes feed on frogs and birds feed on snakes. Marine ecosystems are based on primary production by phytoplankton a category of organisms that embraces an enormous diversity of tiny autotrophs including bacteria cyanobacteria archaea unicellular organisms that are outwardly indistinguishable from bacteria but have a distinct genetic make-up and algae. Marine food webs are generally more complex than those of terrestrial biomes. They can extend to five and in kelp forests six trophic levels and in an unmatched complexity the richest coral reefs may go seven. A complete account of biomass within a unit area of any terrestrial ecosystem would show a pyramid-shaped distribution with autotrophs forming a broad base herbivores a smaller second tier omnivores and first-order carnivores at the next level and the rare top predators at the apex. The mass of the levels varies greatly among ecosystems but phytomass is commonly twenty times larger than the zoomass of primary consumers and the zoomass of top carnivores may add up to less than of phytomass. In marine ecosystems the pyramid is inverted the brief lives of phytoplankton mostly between 12-48 hours and the high consumption rates by zooplankton and larger herbivores mean that the total standing heterotrophic biomass could be between two and four times as large as the mass of the .
