The article discusses how different species in aquatic ecosystems are organized based on what they eat. Plants make food from sunlight, herbivores eat plants, and carnivores eat herbivores. This creates a food web that shows who eats who. Some species eat at different levels, so they get a fraction like 2.5. Scientists use field data to understand how energy moves through the food web. The efficiency of this energy transfer can vary based on the environment. In open water, food chains are longer because everything is small and eaten by something bigger. This study helps us understand why some ecosystems are more efficient than others and how different species interact in nature.