Question

If 2,000 kcal of energy are available in algae, how much energy would be available to the water boatmen that eats the algae? To the tortoise that eats the water boatmen?

Answer 1

The energy transfer between trophic levels in an ecosystem follows the principle of energy efficiency, typically described by the 10% rule. This rule states that approximately 10% of the energy from one trophic level is transferred to the next level, while the rest is lost as heat and used for metabolic processes.

1. **Energy available to the water boatmen consuming the algae:**
- Energy available in algae = 2,000 kcal
- Energy available to water boatmen = 10% of energy from algae = \( 0.10 \times 2000 \, \text{kcal} = 200 \, \text{kcal} \)

2. **Energy available to the tortoise consuming the water boatmen:**
- Energy available to the water boatmen = 200 kcal
- Energy available to tortoise = 10% of energy from water boatmen = \( 0.10 \times 200 \, \text{kcal} = 20 \, \text{kcal} \)

So, in summary:
- The energy available to the water boatmen is **200 kcal**.
- The energy available to the tortoise that eats the water boatmen is **20 kcal**.