Food chain: a biological concept, put forward by Elton, is a sequence in which the relationship between eating and being eaten is related to each other, also known as nutrition chain.

Examples of food chains:

1, big fish eat small fish, small fish eat shrimp, shrimp eat zooplankton, zooplankton eat green algae.

2. Eagles eat snakes, snakes eat rabbits, and rabbits eat grass.

3. Snakes eat frogs, frogs eat insects, and insects eat cereals.