There are often many food chains in an ecosystem, and the complex nutritional relationship formed by these food chains is food web. Food web can directly describe the nutritional structure of ecosystem, which is the basis for further study of ecosystem function. For example, if pesticides such as DDT are used to kill pests, the food web structure can be used to predict the organisms that may be affected in the ecosystem and the transfer of DDT in the system.
Extended data
Limited by the efficiency of energy transfer, the food chain generally has 4 ~ 5 links, at least 3. But there are exceptions, such as the Snake Island in China, where there have been seven links of "nectar-flying insects-dragonflies-spiders-birds-poisonous snakes-eagles", but this situation is extremely special.
The food chain can be mainly divided into two categories, one is called grazing food chain, starting from living things; The other is based on dead bodies, which is called debris food chain.
In the ecosystem, the relationship between the actual feeding and being eaten is not as simple as that shown in the food chain. Usually, a creature is eaten by many creatures, and it also eats many other creatures.
In this case, there is a complex universal relationship between biological components in the ecosystem through energy transfer. This kind of connection is like an invisible net, which includes all living things and makes them have some direct or indirect relationship with each other. In this way, in an ecosystem, the food relationship is often very complicated, and various food chains are intertwined to form a food web.
Baidu Encyclopedia-Ecosystem Structure
Baidu encyclopedia-food chain