food chains

    • The arrows in a food chin show the transfer of energy from organism to organism.
    • Food chains always begin with the sun.
    • A producer is a green plant that uses the suns enrgy to produce food energy.
    • Consumers get their energy from eating other living things.
    • A primary consumer eats the producer....
    • A secondary comsumer eats the primary consumer....
    • A tertiary consumer eats the secondary consumer

  • Herbivores--animals that eat only plants.
  • Carnivors-- animals that only eat animals.
  • Omnivores-- animals that eat animals and plants
  • Top carnivores-- animals that are not eaten by anything else except decomposers after they die.

Pyramids of numbers

'pyramids of numbers' are used to represent the feeding relationships between plants and animals in ecosystems.

  • A pyramid or numbers tells us how many organisms are involved at each level of the food chain.
  • Sometimes a pyramid of numbers doesn't look like a pyramid at all as it doesn't take into account the size of the organisms.
  • A pyramid of biomass takes into account the mass of an organism at each level.
Image: diagram showing food pyramid
Image: diagram showing food pyramid

Energy is lost to the surroundings as we go from one level to the next, so there are fewer organisms at each level in this food chain. A lot of clover is needed to support the snail population. A thrush eats lots of snails, and a hawk eats lots of thrushes, so the population of hawks is very small.


Loss of energy in food chain.
  • Food chains rarely have more than fourr or five links in them; this is because energy is lost all the way along.
  • T he energy is used for staying alive,moving,growing and keeping warm, and some of the energy is lost as waste in urine and faeces.
  • Not all of the animal aterial is eaten so not all of the energy is passed on.
  • This loss of energy in a food chain means that the mass of organisms get less at each level

Food webs
  • A food web gives us a more complete picture of what eats what.
  • Most animals in a community eat more than one thing.If one kind of food runs put , they will be able to survive eating something else.
  • Food chains can be drawn for any enviroment.

Image: diagram of a food web
Image: diagram of a food web


Although it looks complex, it is just several food chains joined together. Here are some of the food chains in this food web:

grass--insect--vole--hawk

grass--insect--frog--fox

grass--insect--vole--fox