Food Chains & Webs

• Types of organisms found in food chains & webs

  • Autotrophs/producers
  • Heterotrophs/consumers
  • Decomposers
• Autotrophs/producers

  Organisms that make their own food either using Light energy for photosynthesis or chemical energy for chemo-synthesis. They are the start of every food chain
• Heterotrophs/consumers

  Organisms that consume or eat other organisms to get chemical energy, as they cannot make their own. All animals are consumers
• Decomposers

  Organisms that break down dead organisms and organic matter to obtain chemical energy. In the process, they recycle nutrients
• Herbivore

  An animal that only eats plants
• Carnivore

  An animal that only eats meat
• Energy pyramids and trophic levels

  Food chains can be arranged in energy pyramids. These have different levels called trophic levels. Most food chains are limited to 4 or 5 trophic levels
• The flow of energy between trophic levels is inefficient. In fact, around only 10% of energy stored as biomass in one trophic level ends up as biomass in the next trophic level
• 10% energy transfer rule

  Most energy is lost as heat which is produced during cellular respiration. Some energy is also lost when an organism dies without being eaten, and when parts of an organism are either not eaten or are not digested
• Food webs show all of the food chains in one ecosystem
• Predator

  An animal that hunts & kills other animals for food
• Apex/top predator

  An animal that is at the top of a food chain
• Omnivore

  An animal that eats both meat and plants
• Scavenger

  An animal that eats animals killed by other species
• If a population of a species is lost from an ecosystem it can have devastating consequences. If there are other species that depend upon it as a food source, their numbers can decrease rapidly. This has a domino effect on the entire ecosystem