• Organisms can be classified into trophic (feeding) levels depending on how they get their energy.
  • Organisms that get their energy from nonliving sources (sun, organic matter) are called autotrophs (producers) and make up the 1st trophic level.
  • Organisms that get their energy from other living things are called heterotrophs (consumers).
  • Heterotrophs that eat autotrophs make up the 2nd trophic level and are called primary consumers.
  • The third trophic levels consists of secondary consumers and eat primary consumers.
  • Ecosystems are normally limited to about 5 trophic levels.
  • All energy in an ecosystem is derived from the sun*.
  • This energy is converted to sugar (chemical energy) by plants through the process of photosynthesis.
  • A food chain shows the transfer of energy from one trophic level to another.
  • Whenever energy is transferred, some gets lost.

Energy Pyramids

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  • Since energy is lost each time it is transferred, each trophic level receives less energy than the level before it.
  • Also, energy gets used at each level, so only 10% of the energy from one trophic level gets passed onto the next trophic level.
  • This can be shown using an energy pyramid.
  • The size of the boxes represent the amount of energy in each trophic level.

Ecological Niches

  • The function a species serves in its ecosystem, including what it eats, what eats it, and how it behaves.
  • No two species occupy identical niches.

Types of Consumers

  • A sequence of organisms, each feeding on the next, showing how energy is transferred from one organism to another.
  • pine cone -> red squirrel -> weasel -> goshawk
  • Energy is continuously lost from all levels of the food chain.
  • Food chains do not exist in nature.
  • Create a sample food chain using the following organisms: grass, snakes, snails, birds.
  • What happens when one link is broken in a food chain?
What is Bioamplification?

Trophic Level

  • The level of an organism in an ecosystem depending on its feeding position along a food chain.
  • First trophic level – producers
  • Second trophic level – primary consumers
  • Third trophic level – secondary consumers
  • Fourth trophic level – tertiary consumers

Ecological Pyramids

  • A representation of energy, numbers, or biomass (the mass of living organisms in a given area) relationships in ecosystems.
  • Energy pyramid – Energy loss and transfer between trophic levels; the size of each layer represents the amount of energy available at that trophic level.
  • Only about 10% of the energy taken in by the individuals at one trophic level is passed on to individuals at the next level.
  • 10% of it is used to build new biomass (the rest going to metabolic processes). In a pyramid of productivity each step will be 10% the size of the previous step (100, 10, 1, 0.1, 0.01)

Energy Pyramid

  • Pyramid of Energy Flow
  • 10% passed on to next level (a lot energy is lost as HEAT or to fuel prey’s bodily functions)
  • At each trophic level, the bulk of the energy received from the previous level is used in metabolism
  • This energy is released as heat energy and lost to the ecosystem
  • Eventually, all energy is released as heat

Numbers and Biomass Pyramids

  • In a forest ecosystem, the tiny plant-feeding insects in the second trophic level outnumber the trees in the first trophic level.
  • However, the biomass of all the trees is much greater than the biomass of herbivores.
  • Example Biomass Pyramid

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Bob T.
Bob T.
1 year ago

This helped me

8 years ago

10% of it is used to build new biomass (the rest going to metabolic processes). In a pyramid of productivity each step will be 10% the size of the previous step (100, 10, 1, 0.1, 0.01)

8 years ago

thank you for your information. it help me being a new biology teacher

8 years ago

kilo calories!

swiftie shielo
swiftie shielo
8 years ago

I love this page even if it only displays few informations, one can still learn a lot from it… but what realy is Kcal???

swiftie shielo
swiftie shielo
8 years ago

what is kcal??? coz i don’t know what is it

Reply to  swiftie shielo
3 years ago

I think Kcal is kilocalories

9 years ago

thru eating process..the higher the consumer, the lower energy it gets…..

9 years ago

I think you should put more of an explanation for why only 10% of the energy gets transferred.