Pyramids of numbers

A pyramid of numbers shows the total number of individual organisms at each level in the food chain of an ecosystem.

Food pyramid. Widest at bottom, narrowest at top.  Bottom is 5 flowers, then 3 snails, 2 frogs and a fox.  Pyramid represents total number of organisms at this each level.

A pyramid of numbers does not always have a regular pyramid shape because it does not take into account the biomass of the organisms. An inverted pyramid of numbers can be found in an ecosystem where the community contains a few producers with a very large biomass that support a larger number of smaller consumers.

An inverted pyramid of biomass, The middle level is widest, followed by the top level and the bottom level is the narrowest.  The top level features woodpeckers, the middle level insects and the lowest level oak trees.

An inverted pyramid of numbers can also be found in an ecosystem where the community contains parasites. There can be many more parasites than the hosts they feed on because each individual parasite has a very small biomass.

An inverted pyramid of biomass, The middle level is narrowest, followed by the top level and the bottom level is the widest.  The top level features deer ticks, the middle level red deer and the lowest level heather.

The shape of the pyramid of numbers does not change the shape of the pyramid of energy. For any food chain, producers store the most energy and the energy stored decreases at each level, giving a regular pyramid of energy.

The body size of the organisms or the number of organisms does not change the fact that energy is always being lost as you go up the chain.

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