READ: Energy Flow in Ecosystems

The set of organisms that pass energy from one trophic level to the next is described as the food chain (Figure below). In this simple depiction, all organisms eat at only one trophic level (Figure below).

What are the consequences of the loss of energy at each trophic level? Each trophic level can support fewer organisms.

What does this mean for the range of the osprey (or lion, or other top predator)? A top predator must have a very large range in which to hunt so that it can get enough energy to live.

Why do most food chains have only four or five trophic levels? There is not enough energy to support organisms in a sixth trophic level. Food chains of ocean animals are longer than those of land-based animals because ocean conditions are more stable.

Why do organisms at higher trophic levels tend to be larger than those at lower levels? The reason for this is simple: a large fish must be able to eat a small fish, but the small fish does not have to be able to eat the large fish.