Food webs

The intricate metabolic interactions between the various levels and organisms within an ecosystem, eg. for example, who predate on who, and how many different species feed on and are being fed by a single species is described as a food web. Usually, this is depicted as a network with arrows pointing from providers to consumers.

A food web consists of a number of food chains, which may or may not interact in nodes of predators or prey with other food chains, these interactions are what differentiates a food chain from a food web.

Within the different chains of a food web, there are primary-producers which either take sunlight, or another abiotic energy-source and transform it into biomass, the energy captured by the primary-producers is then made available to consumers.

Primary consumers feed exclusively on primary-producers. Omnivores live on a mix of primary consumers and primary producers (combining herbivory and carnivory) Tertiary consumers exclusively feed on consumers, and can also be known as a predator.

In some contexts, we use quaternary consumer to describe a predator which eats other smaller predators eg the tertiary consumers, another way to describe a tertiary consumer is as an apex predator. They are “the top of the food chain(web)” No one predates on them.

Each step or level is known as a trophic level, a food web is made up of various trophic levels, and each level usually consists of several species. With each step, energy is lost to metabolism and heat generation. We describe the energy transferred from one level to the biomass in the next as feed conversion efficiency.

Cascades