Within the food chain energy can be passed and transferred from one organism to another. Whilst mammals get their energy sources from food – whether this be eating other animals or eating vegetation; plants get their energy from photosynthesis.
Energy is passed between organisms through the food chain. Food chains start with producers. They are eaten by primary consumers which are in turn eaten by secondary consumers.
They are then eaten by tertiary consumers and in a long food day these can be eaten by quaternary consumers. Each stage of a food chain is called a trophic level.
When food chains are linked together they form a food web.
So how does all this energy get into the food web, and how is it then distributed between organisms?
Plants harvest their energy from the sun during photosynthesis. This energy can then be passed from one organism to another in the food chain.
The organism that obtains energy from sunlight is called the producer. Often these are plants but in some circumstances it can be bacteria.
Even though it is producers that bring energy into the food chain from the sun it is consumers that make up the majority of the food chain. These can be predators, scavengers and parasites.
When a plant is eaten by a primary consumer, only 10% of the energy is passed on.
The low percentage of transferred energy can be attributed to different reasons like some of the organism not being eaten, incomplete digestion of the eaten organism, energy lost in excretory processes or energy lost as heat.
Consumers pass 20% of their energy onto other consumers. This is because they are more efficient than plants at passing on the energy. A lot of the energy is lost in excretion and some is lost in trying to maintain a constant body temperature.
When producers or consumers die they will be fed on by decomposers. Decomposers break complex materials into simple components after producers and consumers die, using up the energy they contain. In this way, minerals and elements needed by plants are released in a form that can be absorbed by them.
Sometimes there are plants that need to be killed. Herbicides will kill plants. However, they need to be used carefully as they could cause damage to plants you do not want to kill.
If you are wanting to get rid of pests (organisms that compete with humans for food and space) you would use pesticides or biological controls.
Pesticides are chemicals that are poisonous to pests. You can also use biological controls (other organisms) to get rid of pests. The organisms used as biological control are normally either predators or parasites of the pest organism. An example of this type of control is the ladybird, which feeds off aphids. Aphids can cause severe damage to crops.
However biological controls often act slower than pesticides. Also they can be bad as the organism itself may become the pest in time.
In the cause of transferring energy in animals, many farmers will restrict movement so that less energy is lost. In turn this energy can be transferred into body mass.
Also, the environment can be kept warm to reduce heat loss from the body.