Trophic Levels – is the position an organism occupies in a food chain. It refers to food or feeding


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Trophic Levels – is the position an organism occupies in a food chain. It refers to food or feeding.

  • Trophic Levels – is the position an organism occupies in a food chain. It refers to food or feeding.

  • Apex predator – top level predators with few or no predators of their own.





The energy flow from one trophic level to the other is know as a food chain





Most organisms eat more than JUST one organism

  • Most organisms eat more than JUST one organism

  • When more organisms are involved it is know as a FOOD WEB

  • Food webs are more complex and involve lots of organisms



Food webs show ALTERNATIVE PATHWAYS other possible pathways through which an organism can obtain energy

  • Food webs show ALTERNATIVE PATHWAYS other possible pathways through which an organism can obtain energy











When a lion eats a zebra, it does not get all of the energy from the zebra.

  • When a lion eats a zebra, it does not get all of the energy from the zebra.

  • Energy lost is usually in form of heat

  • Energy lost from chain “link” to “link” is significant!







Each level above only gets 10% of the energy from below

  • Each level above only gets 10% of the energy from below

    • Ex: 10,000 J of producers (plants) only give 10% of energy to primary consumers
      • 1,000 J to primary consumers (snails, minnows, dragonflies)
      • 100 J to secondary consumers (small fish)
      • 10 J to tertiary consumers (big fish)
      • 1 J to quaternary consumers (fish hawk)












Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)

  • Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)



Usually no more than 5 trophic levels since 6th level would have very little energy to keep it alive

  • Usually no more than 5 trophic levels since 6th level would have very little energy to keep it alive





Shows the numbers of individual organisms at each trophic level in an ecosystem.

  • Shows the numbers of individual organisms at each trophic level in an ecosystem.



Biomass is a measure of the total dry mass of organisms in a given area.

  • Biomass is a measure of the total dry mass of organisms in a given area.




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