Feeding Relationships

Food Chains and Food Webs

A food chain shows the transfer of energy from one organism to another, beginning with a producer.
Each stage in a food chain is called a trophic level.
A food web is a complex network of interconnected food chains, showing how energy transfers through an ecosystem.

Producers are organisms that can produce their own food through photosynthesis, such as green plants.
Consumers are organisms that obtain energy by eating other organisms.
Consumers can be categorised as: primary consumers (herbivores that eat producers), secondary consumers (carnivores that eat primary consumers), and tertiary consumers (carnivores that eat other carnivores).
Decomposers are organisms that break down dead or decaying organisms, returning nutrients to the soil for reuse by producers.

Energy is transferred from producers through various trophic levels via consumers when they eat.
Energy transfer is not 100% efficient — at each level, much of the energy is lost through bodily functions or as heat.
As energy is lost at each trophic level, there are usually only a few levels in a food chain. This is known as the energy pyramid.

A predator is an organism that captures and eats other organisms (the prey).
A prey is an organism that is eaten by a predator.
The number of predators and their prey in an ecosystem are closely linked and often show cyclical changes.

Biomass refers to all the living material in an organism. It is a measure of the number or mass of organisms at each trophic level.
The pyramid of biomass shows the mass of organisms at each trophic level in a food chain.
Energy and biomass decrease at each higher trophic level - this is depicted in a pyramid of energy.

Predator and prey organisms exhibit different adaptations to enhance their survival.
Predators may have adaptations for efficient hunting, such as sharp teeth and claws, keen senses, and the ability to run quickly.
Prey animals may have adaptations to avoid predators, including camouflage, warning colouration, and defensive structures like shells and spines.