pyramids of biomass

• Pyramid of biomass


  Shows the biomass of each trophic level in a food chain
• Biomass


  The mass of living organisms
• The bars in the pyramid get smaller as you go up the trophic levels
• The total mass of organisms in each trophic level is decreasing
• Even though each individual snake might weigh more than each rabbit


  There would be a lot fewer snakes than rabbits, so the total mass of snakes is much lower than the total mass of rabbits
• Only about 10% of the biomass and energy is transferred up to the next trophic level
• Reasons why only 10% of biomass and energy gets passed on

  • Organisms don't eat every single part of the organism they're consuming
  • The bits that are eaten might not be absorbed if they can't be broken down properly
  • Most of the nutrients that animals absorb are used to release energy through respiration rather than for growth
• Efficiency of biomass transfer

  The percentage of the biomass that has passed on to the next trophic level
• Calculating efficiency of biomass transfer

  Biomass transferred to the next level / Biomass available at the previous level x 100
• Efficiency calculations


  • Snakes to rabbits: 15 kg / 144 kg x 100 = 10.4%
  • Snakes to hawks: 1.6 kg / 15 kg x 100 = 10.7%