Food Webs

Food Webs

1. producers at the bottom up trophic levels to top predator

2. Autotrophs (producers) make their own energy using sunlight

3. Second trophic level = herbivores

4. Secondary consumers consumer herbivores

5. Apex predators (top of foodchain)

6. 90% of energy is lost between trophic levels

   • so foodchains are short with 4-6 links
     • Exchange of energy up foodchain

7. Complex

   • more than one food chain in an ecosystem
     • Organisms consume a wide variety of food and have a range of predators
       • Organisms may eat herbivores and small carnivores, their prey may be shared with other species = overlapping food webs
   • Basic = observations of who eats who
   • Energy flow diagram
     • shows significant links in terms of the amount of energy exchanged
   • Functional links
     • only detected using experiments
     • Breaking links and recording the effects
       • A significant change in population numbers would determine that the link is functionally important
     • Eg. Starfish & Mussels. when starfish is removed the mussel outcompetes other organisms, starfish keep numbers low enough for other species to colonise the area