pyramids of biomass

• Pyramids of biomass show the biomass of each trophic level in a food chain
• Grass is the producer

  • Rabbits are the primary consumer
  • Snakes are the secondary consumer
  • Hawks are the tertiary consumer
• Biomass refers to the mass of living organisms
• Bars in the pyramid represent the total mass of organisms at each trophic level
• Total mass of organisms decreases as you move up the trophic levels
• Only about 10% of biomass and energy is transferred up to the next trophic level
• Reasons for only 10% transfer:

  • Organisms don't eat every part of what they consume
  • Not all consumed parts are absorbed and some are excreted as waste
  • Most nutrients absorbed are used for energy through respiration rather than growth
• Efficiency of biomass transfer calculation:

  • Efficiency = (Biomass transferred to the next level / Biomass available at the previous level) x 100
  • Example: Efficiency between snakes and rabbits = (15 kg / 144 kg) x 100 = 10.4%
• Efficiency between snakes and hawks = (1.6 kg / 15 kg) x 100 = 10.7%