1.4 Ecological Pyramids (Sec 2.5 pg 39-41)

We can represent the pathways that energy takes through an ecosystem with an ecological pyramid (a.k.a. food pyramid). There are three types; all have producers on the bottom, then primary consumers, then secondary & tertiary consumers.

– Pyramid of Energy = each level represent the amount of energy available to the next level. – Only about 10% of the energy of each level is passed on to the next! – Most energy at any level used for basic life processes (movement, reproduction, etc.)

– Pyramid of numbers = each level represents the actual number of individuals in that trophic level. – Shapes vary widely depending on the physical size of producers (e.g. grasslands have LOTS of individual grasses; mature forests have much fewer large trees)

– Pyramid of mass = each level represents the total mass of the organisms in that trophic level. – Most communities have the standard shape shown here (there is a consistent pattern to the biomass at each level across most communities)