Chapter 3

• Ecological Pyramids


  Graphical representations of the relative amounts of biomass or numbers of organisms at each trophic level in an ecosystem
• Hawk


  • 1 kcal
  • Snake 10 kcal
  • Frog 100 kcal
  • Grasshopper 1,000 kcal
  • Grass 10,000 kcal
• kcal


  Kilocalories, a unit of energy
• Ecological Pyramids


  • Instead of representing trophic levels in a food web, an ecological pyramid can be used
  • Energy decreases as you go up the pyramid
  • Only a small percentage of energy is available for the next trophic level
• • Hawk 1 kcal
  • Snake 10 kcal
  • Frog 100 kcal
  • Grasshopper 1,000 kcal
  • Grass 10,000 kcal
• Pyramid of Energy


  Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web
• Pyramid of Biomass


  Illustrates the relative amount of living organic matter available at each trophic level
• Pyramid of Numbers


  Shows the relative number of individual organisms at each trophic level
• Pyramids of Aquatic Ecosystems
• Phytoplankton are microscopic and weigh very little