18-3 Energy Transfer

1. 18-3 Energy Transfer Producers and Consumers

2. Objectives • Summarize the role of producers • Identify kinds of consumers • Explain the role of decomposers • Compare food chains and food webs • Explain why there are only a few trophic levels in an ecosystem

3. Producers • Autotrophs: make their own energy/food • As producers they make energy that other organisms can use • Photosynthesis: Energy from light • Chemosynthesis: Energy from chemicals

4. Deep sea ecosystems survive on chemosynthesis

5. Measuring productivity • Gross primary productivity: Rate that producers catch sun’s energy • Producers store energy in sugars • Biomass: All the organic material • Net primary productivity: how much biomass piles up • GPP minus rate of respiration • Kcal/m2/year • g/m2/year • Where do you think there is high Net PP • What about aquatic environments?

11. Consumers • Heterotrophs: get energy from outside of themselves • Eat or consume something else

12. Vore = Eat • Herbivore: eat producers (plants or herbs) • Carnivore: eat other consumers • Carn = flesh • Omnivore: eat everything • Omin = all • Most things are really at least a little bit of an omnivore, even lions • Detrivore: eat waste • Detri = garbage • Decomposers important

13. Others • Insectivore • Bovivore • Planktavore • Cannibal: happens in nature • Black widows, Mantis : eats the father • Mice will kill the babies if the nest is repeatedly threatened • Many father’s kill the young • Why do this?

14. Energy flow • When you eat something energy moves into you • Trophic level: where do you fit in the food chain? Who eats you and who do you eat?

16. Food Webs • There are many trophic relationships • Food webs show the many connections between eater and eaten

19. Energy transfer • How much does each trophic level store? • Only 10% of the energy makes it up to the next level • Why is so much energy lost? • Some prey escape • You can’t eat everything when you do catch prey • Entropy: energy is always lost • There are only a few trophic levels because energy runs out

23. How do producers and consumers obtain energy? • Producers: from light or chemicals • Consumers: from eating something else

24. Name four types of consumers • Herbivore • Carnivore • Detrivore • Insectivore

25. What important role do decomposers play in an ecosystem? • Decomposers remove wastes preventing them from building up.

26. How does a food chain differ from a food web? • Food chains are linear (straight) • Food webs are spatial, and show more connections

27. Give two reasons for the low rate of energy transfer within ecosystems • Some prey escape • You can’t eat everything when you do catch prey • Entropy: energy is always lost

28. Explain why food chains usually do not exceed three to four levels • There is a low rate of energy transfer • Very little energy gets transferred up • Soon there isn’t enough energy to sustain life

29. American Pieta

30. What happens to an ecosystem if all the plants die? What happens if all the decomposers die? • If the plants die then the herbivores die, and then the carnivores die. • If decomposers die then waste will pile up eventually poisoning the ecosystem

31. What is unreasonable about an ecosystem with 7 levels? • There are to many levels because There is a low rate of energy transfer • Very little energy gets transferred up • Soon there isn’t enough energy to sustain life

32. Explain why there are more herbivores than carnivores • Herbivores get energy from the largest source of biomass: plants • Carnivores can’t get as much energy by eating other consumers

33. This Biology Lecture brought to you by Muppet Star Wars