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 SunAlgae BacteriaFish 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 SunAlgae BacteriaFish 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