Energy in Ecosystems

• Levels in a food chain

  • Plant
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
• Not all the energy is transferred

  The majority of the energy is lost as heat, movement, undigested materials, growth
• Secondary consumer


  The animal that eats the primary consumer
• Energy flow

  1. Energy is transferred from the plant to the animal

  2. Energy is again transferred and so on through a series of organisms
• All energy comes from the Sun
• Primary consumer


  The animal that eats the plant
• Tertiary consumer


  The animal that eats the secondary consumer
• Most of the energy available is lost
• As you move from one level to another in a food chain

  Not all the energy is transferred
• Irregular Pyramids of Numbers

  • Single large plant
  • Oak tree caterpillar
  • Shrew
  • Owl
• Primary consumer


  An organism that eats only producers
• Primary consumers

  • Water flea
  • Oak tree caterpillar
• Producer


  An organism that produces its own food, usually through photosynthesis
• Secondary consumers

  • Stickleback
  • Shrew
• Irregular Pyramids of Numbers


  A diagram that shows the relationship between different levels of consumers in a food chain, where the number of organisms decreases as you move up the chain
• The relationship takes the form of a pyramid because the energy loss at each link in the food chain limits the quantity of living matter that can be supported at the next level
• Secondary consumer


  An organism that eats primary consumers
• Producers

  • Alga
  • Oak tree
• Tertiary consumers

  • Pike
  • Owl
• The final consumer tends to be less in number than the one below
• Tertiary consumer


  An organism that eats secondary consumers
• In some food chains the producer is a larger organism than the one below
• The pyramid of numbers for the food chain takes a different form in some cases
• Energy from

  • Sun converted into plant tissues
  • Plant tissue converted into tissues of primary consumer
  • Energy from primary consumer converted into tissues of secondary consumer
  • Energy from secondary consumer converted into tissues of tertiary consumer
• Stages in a food chain

  • Producer
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
• Pyramid of Numbers


  Shows the total number of organisms at each stage in a food chain
• Pyramid of Energy

  Shows the total available energy at each stage in a food chain
• 93,000 kJ/m²/year of energy is available from the producer
• The pyramid of energy is always upright, with a large energy base at the bottom (producer)
• Depending upon the number of organisms, the pyramid of numbers may not always be upright, and may even be completely inverted
• Producer


  Has the biggest segment in the pyramid of energy
• 811 kJ/m²/year of energy is available from the sun