• Pyramids of energy illustrate the?amount of energy contained?within the?biomass?of organisms at each trophic level
• The?length?of each box, or bar, represents the quantity of energy present
  • Pyramids of energy?should be drawn?to scale?so that each bar is?proportional?in size to the amount of energy that it represents
  • In some situations, however, a pyramid of energy may be an approximate sketch where each bar is a rough representation of the energy contained
• These pyramids are always?widest at the base?and decrease in size as they go up
  • The base is wide due to the large amount of energy contained within the biomass of producers
• Pyramids of energy show a?stepped?decrease?in the energy contained at each level of the food chain rather than appearing as pyramid with smooth sides
• The levels of a pyramid of energy should be labelled?producer,?first consumer,?second consumer, and so on
• The units used should be the amount of?energy, per unit area, per year?e.g. kJ m^-2?year^-1
• As you move up the pyramid to higher trophic levels, the quantity of energy decreases as?not all energy is transferred?to the biomass of the next trophic level (roughly 10 % of the energy is passed on)
• Energy is lost at each trophic level due to
  • Incomplete consumption
  • Incomplete digestion
  • Loss of heat energy to the environment during respiration
  • Excretion of the waste products of metabolism e.g. carbon dioxide, water, and urea
• As a result of this, the biomass at each trophic level will also decrease as energy availability decreases

The energy stored in the biomass of organisms can be represented by a pyramid of energy