| Autotrophic nutrition
The biological process that we call life requires chemical energy released via resperation. Chemicals are broken down to release energy not genrally avalable in the enviromant but normally built up be smaller molucules by some living organisms known as autotrophs.
To build high-energy molecules the autotrophs need a source of energy. They use this to make carbohydrates such as glucose, starch and cellouse, also lipids such as fats and oils. Most are photoautotrophs that are organisms that produce high energy food substances using light. These include flowers, trees, algae, etc. Some however are chemoautotrophs, such as bacteria which harness energy by oxidising inorganic substances such as hydrogen sulphide and ions of ammonium and nitrite.
Heterotrophic nutrition
Organisms that can't produce their own hight energy molecules however must gain their energy from other organisms. These are hetrotrophs which include animals, fungi and many bacteria.
Almost 100% of energy input comes from autotrophs. Many aAutotrophs can survive without heterotrophs but it is unlikely that any Heterotrophs would survie if there were no Autotrophs (So yere, we'd probably be dead now if it weren't for organisms like algae). This can be seen most clearly when considering where most energy comes from in a particular food chain. Most of the energy is recieved in a particular trophic level (say for example, secondary consumers such as catapilers) which is gained from the trophic level under it (Primary producers for example, such as flowers).
As energy goes up each particular trophic level, the energy becomes less and less. This is one reason why it is considered more efficient to raise crops rather than cattle as though cattle have a more concentrated energy source, a lot of energy is wasted through bodily processes. Hense, the greatest amount of energy will be at the lowest and first trophic level. All livestock are heterotrophs, and are classifeid depending on what food they eat:
Herbivores:
Get energy from plants. Many are ruminants and have large and complex stomach needed to digest certain organic material. The rumen is a large stomach chamber where sybiotic bacteria digest cellulose, allowing material to be utilised. Humans cannot digest this substance as we do not have the nessesary components to effectively digest this and other organic compounds found in plants, leading to our bodies being less effeciant in digesting matter in some respect. This also allows herbivors to feed any place where there is vegitation.
Carnivores:
These eat other animals, so have a smaller food energy resource than herbivores. A benifit however is that eating meat may contain more nutrients then plant food due to nutrients that the prey animal consumes going into the prey species bodymass, which is consintrated over time.
Omnivores:
Pigs, Humans, etc can digest both plant matter and meat, but fewer can digest cellulose. This allows omnivores species to be fed on a wide variety of waste substances, so could be seen as cheaper in some respects than a species that is primarily carnivores or a herbivore.
Edited by ex nihilo - 9/2/2012, 19:45
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