4.5 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

Food chain
A food chain shows the flow of energy up the food chain. It can only show one organism at each trophic level, also you cannot tell whether the organism is feeding at more than one.


Here is an example of a food chain...

Food web
A food web gives a better understanding of a certain ecosystem by linking several animals within a habitat showing which organisms consumes which etc. A food web basically just shows multiple different food chains, that are all linked together. They show multiple different trophic levels including multiple prey and multiple predators. This means an organism has the potential to be a secondary or tertiary consumer at the same time.

Here is an example of a food chain...

Pyramid of numbers
A pyramid of number shows the number of each organism (of each trophic level of a certain food chain) by the area of the block in the pyramid. E.g a large block is lots of that animal, a little block means few of that animal.

Here is an example of a pyramid of numbers...

Pyramid of biomass

A pyramid of biomass is a bit like a pyramid of numbers, only it represents the dry mass of each consumer (and producer), again, by the area of a pyramid block.


Here is an example of a pyramid of biomass...

Pyramid of energy

A pyramid of energy, again looks like a pyramid of numbers/biomass, but it shows the transfer/flow of energy through the food chain.

Here is an example...

NOTE: The amount of energy transferred decreases by 10% each time, this is important (this is explained in 4.6).