Food chains & webs

• Food chain - shows the feeding relationship between organisms and the energy transfer
• Food chains;

  Producer (makes their own food from sunlight)

   ↓ 

  Primary consumer (eats producers)

  ↓ 

  Secondary consumer (eats consumers)

  ↓  

  Tertiary consumer (eats consumers)
• As energy is passed up the different levels most of it gets lost.
• Predator - a consumer which hunts other animals
• Prey - organisms which are hunted by other organisms
• Biomass - total dry mass of an organism
• Predator and prey cycle;

  • In a stable community the number of prey and predators will always rise and fall.
  • If population of prey increases, so will the population of predators.
  • The will cause the number of prey to start to decrease, as there is more predators.
  • Eventually, there won't be enough prey for all predators, their population will also start to decrease.
  • This allows the prey population to increase, and the cycle will start again.
• Trophic levels can also be used instead to producers and consumers. The 1st tropic level are producers, the 2nd tropic level are primary consumers and 3rd trophic level is secondary consumer, etc.
• There usually isn't more than 4 or 5 trophic levels because not enough energy will be passed on the allow for the organism to survive.
• Only 10 % of the energy that is in each tropic level is passed on to the organisms into the trophic level above.