生态系统由三个营养集团组成:生产者(主要是植物),它参与光合作用,用光能合成有机食品;消费者(主要是动物);分解者(细菌和真菌)。太阳能使生态系统运转起来,各个水平上的生物为了生存吸收所需的能量,于是构成了食物链。在这个食物链中,有的生物吃别的生物,然后又被另一种生物吃掉。于是,能量在系统中流动,从某一水平生物到下一个水平生物。但是,这种能量转换并不是效率很高的, The ecosystem is made up of three nutrition groups: producers (mainly plants), which participate in photosynthesis and synthesize organic foods using light energy; consumers (mainly animals); disintegrators (bacteria and fungi). Solar energy makes the ecosystem work, and all levels of living things absorb the energy they need to survive, thus forming the food chain. In this food chain, some creatures eat other creatures, and then they are eaten by another creature. Thus, the energy flows in the system, from a horizontal creature to the next horizontal creature. However, this energy conversion is not very efficient,