Energy Flow In An EcosystemUnit 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

1st – producers (autotrophs – get their energy from the sun) 2nd – primary consumers (usually herbivores)

Heterotrophs Eat the producers

3rd – secondary consumers (usually carnivores) Heterotrophs Eat primary consumers

4th – 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