1. Cycling of energy Food Chains and Food Webs

2. Energy exists in many forms  Radiant energy (from sunlight)  Chemical energy (for example, glucose)  Kinetic energy (movement)  Potential energy (stored energy, for example, the starch in potatoes)

3. All ecosystems require an energy source  Usually radiant energy (sunlight)  A lot of sunlight is reflected away from earth, and some has other fates. Only about 1% is used in photosynthesis.  Occasionally energy from other sources (eg. Deep sea volcanic trenches)

4. Energy flows  Energy moves through the ecosystem  Must continually be supplied  Captured by PRODUCERS (plants, usually), made into chemical energy  Some energy used by plants, some available to consumers (via ingestion)

5. Trophic levels RADIANT ENERGY FROM SUNLIGHT Trees, shrubs, grasses, ferns PRODUCERS 1 st trophic level Phytoplankton, algae Herbivores Plant eating insects, small birds, possums PRIMARY CONSUMERS 2 nd trophic level Zooplankton, whelks Carnivores Owls, small marsupials SECONDARY CONSUMERS 3 rd trophic level Starfish, small fish Snakes, eagles TERTIARY CONSUMERS 4 th trophic level Large fish, sharks

6. Activities Watch video, answer questions Glossary words: radiant energy, chemical energy, trophic levels Quick check pg 446

7. The food chain Producers Primary consumers (herbivores) Secondary consumers Tertiary consumers Arrows point in the direction of the energy flow; ie, UP the food chain About 90-95% of energy is lost at each step of the food chain! 100 units lost as heat 120 units of chemical energy 20 18 units lost as heat 2 Where does “lost” heat go? Most of it is used in cellular respiration, and “lost” as heat. A bit is lost in waste. Some is stored, and that is the energy that is passed to the next trophic level

8. Energy needs  Warm blooded animals need more energy to maintain their body temperature, as well as all other metabolic functions  Only a small amount of the energy from food is used to make new tissues

9. Energy loss  Because only about 10% of energy is transferred to the next trophic level, we can assume that 100g of plant material can provide 10g of caterpillar tissue, which will then only provide 1g of spider tissue.

10. Conclusions about energy loss 1.Number of trophic levels limited 2.Higher level organisms need more energy for tissue production 3.Energy must continually be supplied to the ecosystem

11. Activities Glossary: energy flow, food chain, food web Quick check pg 452 Food chains and food webs activity