Introduction

Digestion efficiency (DE) and ecological efficiency (EE) are key concepts in animal physiology and ecology. This article explains how these efficiencies differ between ectotherms (cold-blooded animals) and endotherms (warm-blooded animals), and what this means for energy flow in ecosystems.

Definitions

• Digestion Efficiency (DE):

  • DE = Assimilation / Consumption

  • Measures how much of the ingested food is actually absorbed and assimilated.

• Ecological Efficiency (EE):

  • EE = Production / Consumption

  • Measures how much of the ingested energy is converted into new biomass at the next trophic level.

Comparison of Ectotherms and Endotherms

Digestion Efficiency (DE)

• Endotherms:

  • Have highly specialized digestive systems.

  • High DE (or similar to ectotherms).

• Ectotherms:

  • High DE for their specific diets.

  • Some variation, but generally high.

Ecological Efficiency (EE)

• Endotherms:

  • Low EE because they use a large fraction of assimilated energy for maintaining high metabolic rates and body temperature.

• Ectotherms:

  • High EE because they have lower metabolic rates and do not expend as much energy on thermoregulation.

Evaluating the Options

Given the options:

1. Endotherms have a high DE and ectotherms have a high EE.

   • Closest to correct. Endotherms have high DE, ectotherms have high EE.

2. Endotherms have a low DE and ectotherms have a high EE.

   • Incorrect. Endotherms do not have low DE.

3. Endotherms have a high DE and ectotherms have a low EE.

   • Incorrect. Ectotherms have high EE, not low.

4. Endotherms have a low DE and ectotherms have a low EE.

   • Incorrect. Neither is true.

Conclusion

The main difference is that ectotherms have high ecological efficiency (EE), while endotherms have low EE. Digestion efficiency (DE) is not the main point of difference, but is generally high in both groups.

Given the options, the best answer is:

(1) Endotherms have a high DE and ectotherms have a high EE.