Energy Flow In An Ecosystem Unit 11 - Ecology

Producers  The most important part of an ecosystem  Without a constant energy source, living things cannot survive.  The sun is the main source of energy for all life on earth.  Plants (autotrophs) use energy from the sun to make their own food

Consumers  Many organisms like animals, cannot make their own food. They rely on eating plants or other organisms for their energy. We call these organisms heterotrophs.  Herbivores – eat plants only  Carnivores – eat meat only  Omnivores – eats plants and meat  Detritivores – eat dead or decaying matter (ex - vultures)  Don’t forget decomposers, they are things like bacteria and fungi that break down dead organisms

Energy Flow  Occurs in one direction  Sun  Producers  Consumers  Decomposers/Detritivores

Food Chains  A series of steps in which organisms obtain energy by eating or being eaten  ***Food chains ALWAYS start with a producer (autotroph)

Food Web  In most ecosystems, feeding relationships are more complex than just a food chain. A food web is when feeding relationships among various organisms form a series of connections or web. It links all of the food chains in an ecosystem together.

Trophic Levels  Each step in a food chain or food web  1 st – producers (autotrophs – get their energy from the sun)  2 nd – primary consumers (usually herbivores)  Heterotrophs  Eat the producers  3 rd – secondary consumers (usually carnivores)  Heterotrophs  Eat primary consumers  4 th – tertiary consumers  Heterotrophs  Eat secondary consumers  …..and so on….  At the top, even after the last consumer are the decomposers

10% Rule  Only 10% of all energy available is passed on to the next trophic level  Sun  producers  primary consumers  secondary consumers  etc.  decomposers