A food chain is a linear sequence that shows how energy and nutrients pass from one organism to another through feeding relationships in an ecosystem. It typically begins with a producer, such as a plant or algae, which makes its own food using sunlight through photosynthesis. This energy is then transferred to primary consumers (herbivores) that eat the producers, followed by secondary consumers (carnivores that eat herbivores), and sometimes tertiary consumers (carnivores that eat other carnivores). The chain may end with apex predators or decomposers that break down dead matter
. Each step in the food chain is called a trophic level, and energy transfer between these levels is inefficient, usually around 10%, which limits the length of the chain to about four or five levels
. Food chains are part of larger, more complex food webs because most organisms consume multiple types of food
. In summary, a food chain illustrates the flow of energy and matter from producers through various consumers, highlighting who eats whom in an ecosystem