Food chains and webs not only describe the order in which organism are eaten, but they also describe the

Trophic levels and energy flow on food chains

Explanation:

The trophic level in a food chain (or web) corresponds to the position of each living being in relation to its energy and nutrient flow in relation to the others.

There are three types of basic trophic levels:

Producers - Plants and other photosynthetic and chemosynthetic organisms

Consumers (food chains usually have more than one) - Herbivores, Carnivores and Omnivores

Decomposers - Bacteria and Fungi

An example food chain according to trophic levels:

Phytoplankton(producer) → Krill (1st consumer) → Penguin (2nd consumer) → Seal (3rd consumer) → fungi and bacteria (decomposers)

Also, it is important to highlight that at each trophic level, less energy is absorbed when a living being consumes the previous one, so the more trophic levels a chain has, the lower the energy flow at the end.