Pyramids of Numbers and Biomass

Pyramids Of Numbers A pyramid of number is a diagram showing the amount of energy lost at each level when an organism eat another organism. There are 4 levels the, producers, the primary consumers, the secondary consumers and the tertiary consumers.

To draw a pyramid of numbers, the number of organisms must be counted for each feeding level. This is done for a given area. Once you have gathered your information you must draw the chart. You use horizontal blocks representing the number of organism drawn to scale on graph paper. The block representing the food producer is placed at the bottom of the diagram. You then place other blocks representing the other feeding levels to give a pyramid shape.

Problems With Numbers There is a problem however with the way a number pyramid works. If you were to do a number pyramid and you wanted to use oak leaves as the producer, instead of counting all the oak leaves on the tree you might decide to use the entire oak tree. This then means that that one oak tree counts as the same as one caterpillar, despite the size difference. This affect can produce misleading diagrams like the one shown here. Therefore it is better to construct a pyramid of biomass.

Pyramids of Biomass Biomass is a measure of the mass of living tissue in an organism. A pyramid of biomass gives a better diagram than the a pyramid of numbers because it shows the loss of mass from producers to consumers in a food chain.

Energy Lost In A Food Chain There is two reasons as to why energy is lost in a food chain, Firstly an organism use up energy to build it’s body. This may include parts such as skin and horns, witch when eaten by another consumer turns out to have very little nutritional value. Therefore these parts are tended to be left uneaten. As a result, that energy is not being eaten and therefore is lost from the food chain. Secondly, most of the energy gained by the consumer is used for moving about and for keeping warm. Much energy is then lost as heat and only about 10 per-cent of energy that is taken in by organism is taken in.

This Production Was Brought To You By… Lizzie Ward-Smith