Download Entry 18: Food Chains and Food Webs

Entry 18: Food Chains and Food Webs
Food Chain: series of events showing who eats who in an ecosystem.
 Always starts with the sun (It’s the origin of all energy in an ecosystem.)
Sun
 Shoots
Vole
Weasel
 Owl
Sun
 Roots
 Beetle
Larva
Salamander  Shrew
 Owl
Producer
1st level
Consumer
2nd Level
Consumer
3rd Level
Consumer
4th Level
Consumer
Autotroph
Heterotroph
Heterotroph
Heterotroph
Heterotroph
Herbivore
Carnivore
Carnivore
Carnivore
Food Web is a series of overlapping food chains in an ecosystem.
Sample Food Web (not related to the above food chains…)
Energy Pyramid: diagram showing energy loss (use) in a food chain.
A food chain can be re-drawn in the form of an energy pyramid.
Owl, 2 kcal
Shrew, 20 kcal
Salamander, 200 kcal
Beetle Larva, 2,000 kcal
Roots ex: 20,000 kcal
*As you move up the levels of the energy pyramid, the number of organisms in each
population DECREASES.
*As you move up the levels of the energy pyramid, the amount of energy left over to pass
to the next level consumer DECREASES. 90% gets used by the organisms at each level
for daily living activities. The left over 10% gets passed to the next consumer when an
organism is eaten.
Energy is measured in calories or kilocalories.