trophic level

An individual layer on the pyramid of numbers which represents types of organisms living at parallel levels on food chains. All herbivores live at one level, all primary carnivores on the next level, all secondary carnivores on the next level, and so on. The animals on each level are remarkably distinct in size from those on other levels; there is a clear jump in size between an insect and a bird, for example.

Trophic level

A trophic level represents a step in the dynamics of energy flow through an ecosystem. The first trophic level is made up of the producers, those within the ecosystem that harvest energy from an outside source like the Sun (or deep-sea thermal vents) and stabilize or "fix" it so that it remains in the system. The second level would comprise those who consume the producers, also known as the primary consumers. The next level would contain the secondary consumers (those who consume the primary consumers), and so on. Because of the limited amount of energy available to each level, these trophic pyramids rarely rise above a third or fourth level of structure. R. Lindeman (1915-1942) was one of the first ecologists to refer to the "trophic dynamics" of ecosystems, doing so in 1942.