Food Chains and Food Webs

Food chains represent the flow of energy and matter within an ecosystem, originating from producers and leading up to the top consumers.
Producers, such as plants, are always at the start of food chains. These organisms use sunlight or chemicals to create their own food (a process called photosynthesis), hence they are also known as autotrophs.
Above the producers are the consumers, who obtain energy by consuming other organisms. These are divided into:
- Primary consumers: They eat producers. Mostly herbivores.
- Secondary consumers: They eat primary consumers. Mostly carnivores.
- Tertiary consumers: They eat secondary consumers. Mostly carnivores. Some, known as apex predators, have no natural predators.
Decomposers (like bacteria and fungi) and detrivores (like worms and beetles) play a crucial role as they break down dead organisms and organic waste, recycling nutrients back into the ecosystem.
Food chains are simple representations of feeding relationships. However, many organisms eat more than one type of food, so food webs (a system of interlinked food chains) provide a more realistic model of energy flow in an ecosystem.
Energy is lost at each trophic (feeding) level in the food chain or web, primarily as heat resulting from metabolic processes, such as respiration. Only a small percentage (typically about 10%) of energy is transferred from one level to the next. Hence, most ecosystems have a limited number of trophic levels.
Human activities, including deforestation, emissions, and the use of pesticides, can disrupt food chains and food webs, impacting the balance of ecosystems and biodiversity.