Food chain and Food webs.
Energy Transfer in a Food Chain.
A food chain shows how energy, in the form of food, Is transferred from one organism to another.
Energy is transferred along food chains from one stage to the next. But not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next.
The energy transferred decreases along a food chain as some energy is used up or lost to the surroundings mainly in the form of heat through each link in the food chain.
Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways:
- energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings
- energy is lost in waste materials, such as faeces.
The pyramid of numbers
The population of each organism in a food chain can be shown in a sort of bar chart called a pyramid of numbers. The more organisms there are, the wider the bar. The producer in the food chain always goes at the bottom of the pyramid of numbers.
The pyramid of numbers shows that the number of producers is greater then the number of herbivores and the number of herbivores is greater then the number of carnivores.