Food Chains

• The arrows of a food chain point toward the right

• The chain starts at the left at the level of the producers

• Why?– The arrows point toward the consumers

at the next trophic level

• Producer:– Produces (makes) energy for the

consumers– Ex: plants (make their own energy)

• Consumer:– Obtains energy by eating other

organisms– Ex: animals, birds, insects

2. Indicate the producers and the consumers

Sun Algae Bacteria Fish

Sea Lion Polar Bear

The Trophic Levels

• The different levels within a food chain

• There are rarely more than four trophic levels in a food chain...

• But it is not impossible to have more!

3. Indicate the trophic levels

Sun Algae Bacteria Fish

Sea Lion Polar Bear

4. Straight Line or Cycle?

• Food chains are continuous cycles

• The animals at the top level die and their bodies are reabsorbed into the soil in the form of nutrients

• This restarts the source of energy (along with the sun) in plants

5. Biodiversity

• The degree of variation in the biotic components (living organisms) of an ecosystem

6. Why is it Important?

• Biodiversity increases the productivity of an ecosystem

• Examples:–More species = more meal options– Populations will be more sustainable–More plant species = more sources of

energy for consumers

7. The influence on the chain

When we take a species out of a food chain...

• It will no longer be able to provide its energy to other organisms

• The organisms at the nest level will not be able to eat them

• Biodiversity decreases

Food Webs/Networks

• The position of the animal depends on what they are eating at the time

• For example:–When a mouse is eating grass, he is a

primary consumer (trophic level 2)–When he eats insects, he is a secondary

consumer (trophic level 3)

8. Food Web

Level 1 Level 2 Level 3 Level 4

• The organisms are placed in the food web based on the food source that is at the lowest trophic level

• Their position may change when the food/energy source changes

9. Energy

• The energy consumed is mostly used for cellular reproduction

• It is also used for regular bodily functions (breathing, walking, etc)

• Energy is converted into heat to keep warm-blooded animals warm

10. Dead Organisms

• Animals and plants die and decompose

• The nutrients are reabsorbed into the soil

• The restarts the energy source (along with the sun) for the plants

• Heterotrophic:– Uses organic compounds as a source of

carbon and a source of energy – Need to eat!– Energy is absorbed through cellular

membranes

• Autotrophic:– Uses energy from the sun to create

organic compounds– Create their own food/energy

12. Energy Pyramid