Ecology

• Habitat


  The area where an organism lives
• Niche


  The full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. It is an organism's occupation in its habitat.
• Producers


  • Autotrophic organisms that make their own food
  • Phototrophic organisms use photosynthesis and contain chlorophyll
  • Chemotrophic organisms use chemicals other than H2O, such as H2S
• Consumers


  • Heterotrophic organisms that cannot make their own food and must ingest (eat) other organisms
  • Herbivores feed on vegetation (producers)
  • Carnivores feed on herbivores or other carnivores
  • Secondary carnivores feed on herbivores
  • Tertiary consumers feed on other carnivores
  • Omnivores feed on both producers and consumers
  • Scavengers feed on dead or decaying organisms
• Decomposers


  • Heterotrophs that recycle small, often microscopic bits of dead organic matter into inorganic nutrients available for plants to take up from the soil
  • Bacteria and fungi are decomposers, most worms are plant scavengers
• Energy in the ecosystem

  1. Energy from the sun enters the ecosystem when producers use it to make organic matter through photosynthesis

  2. Glucose is the primary energy source (carbohydrate) produced by photosynthesis

  3. Consumers take in this energy when they eat producers or other consumers
• Plants absorb less than 1% of the sunlight that reaches them
• Photosynthetic organisms make about 170 billion metric tons of food each year
• The energy captured by producers is used to make cells in both producers and consumers
• Trophic levels


  The different feeding levels of organisms in an ecosystem
• Biomass

  The total amount of organic matter present in a trophic level
• 10 percent law


  Most of the energy that enters through organisms in a trophic level does not become biomass. Only energy used to make biomass remains available to the next level. When all of the energy losses are added together, only about 10% of the energy entering one trophic level forms biomass in the next trophic level.
• Ecological pyramids


  • Diagrams that show the relative amounts of energy, biomass, or number of organisms in different trophic levels in an ecosystem

  
• Food chains


  A series of organisms that transfer food between the trophic levels of an ecosystem using only one species at each level
• Food webs


  A network of food chains representing the feeding relationships among organisms in an ecosystem
• Relationships in the ecosystem

  • Neutralism
  • Commensalism
  • Mutualism or synergism
  • Ammensalism
  • Parasitism, predation
  • Competition