Ecological Pyramids

Slide 1

• The pyramid of numbers shows the numbers of organisms at each trophic level in an Eco-system. The amount of organic material at each trophic level is know as the standing crop. This represents the energy available to the next trophic level. Because there is a limited amount of energy available to support life, predators must always be fewer in number than prey, starvation may result in, bringing the number of predators back into balance.
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• Caption: Ecological Pyramids

Slide 2

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• In the food chain, each individual usually is larger than the organism it eats. However, the lower down on the food chain, the greater the number of organisms. Therefore the total mass of organisms, or biomass, at each lower level is greater than the mass at the higher level. The pyramid of mass shows the biomass available at each trophic level. The producers form the greatest mass, while larger carnivores at the top of the pyramid form the smallest total mass. The total mass of the standing crop can be expressed as the biomass of that trophic level. The organisms at each level carry out activities that use or release most of the energy they obtain, Only 10% of the total energy at each level is passed along the food chain.