ECOLOGICAL PYRAMIDS

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ECOLOGICAL PYRAMIDS

• There are three types of Ecological Pyramids
• 1. Pyramid of Energy Flow
• 2. Pyramid of Numbers
• 3. Pyramid of Biomass

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• PYRAMID OF ENERGY FLOW
• measures the total chemical energy that flows
  through each trophic level
• impossible to invert because there is always less
  energy available for each successive trophic
  level
• food chains will rarely have more than 4 links

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Pyramid of Energy Flow
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• PYRAMID OF NUMBERS
• the concept that numbers of organisms decrease as
  one progresses toward the top of a food chain
• there are more energy available at the first
  trophic level, therefore there are more organisms
  at this level
• counting organisms is a useful way to estimate
  the energy that is present in each trophic level
• most animals are larger than the food they eat (a
  robin eats small worms, big fish eats little
  fish)
• there are exceptions, the result of which is a
  reverse pyramid of numbers (there are thousands
  of beetles that may feed on a single tree)

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Pyramid of Numbers
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• PYRAMID OF BIOMASS
• using numbers of organisms to make a pyramid of
  numbers does not take into account the sizes of
  the individual organisms
• biomass an alternative measure of energy, which
  combines the number with the size of an organism
  it is often calculated as the total dry mass of a
  given population or organisms
• pyramid of biomass is the concept that the mass
  of all organisms in each trophic level decreases
  as one progresses towards the top of a food chain
• an exception would be algae, which are food for
  masses of zooplankton the biomass of the
  zooplankton may be greater than the biomass of
  the algae but this system does not collapse
  because the algae grow and reproduce at a faster
  rate than the zooplankton

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Pyramid of Biomass