1. Energy flow in Ecosystems
Section 16.2

2. Energy is needed for life
Most life on Earth gets its energy from the sun
Photosynthesis takes the sun’s energy and converts it to food energy
Plants that can do this are called producers
All other organisms, which have to get their food from plants or from organisms that eat plants, are called consumers

3. Plant  plant eater  animal eater  decomposer
Food chains
Organisms are assigned a trophic level to represent where they fit in the movement of energy
If we show just one set of trophic levels we have a food chain:
Plant  plant eater  animal eater  decomposer
Consumer trophic levels:
Herbivores – plant eaters
Carnivores – meat eaters
Omnivores – eat both plants and meat
Detritivores – eat organic wastes and dead bodies
Decomposers – cause decay

4. Food webs Food chains only show one series of energy transfers
Food webs show all the possible food chains

5. Energy loss in food chains
Every time energy moves from one trophic level to the next, 90% of it is lost
We represent this loss of energy with an energy pyramid