1. 3.3: Energy Flow in Ecosystems

2. Feeding Relationships
energy flows through an ecosystem in one direction – from producers to various levels of consumers 2 2

3. food chain: simple energy path through an ecosystem3 3

4. More Food Chains 4 4

5. any food chain starts with the producer – the group that collects the sun’s energy directly for use by the rest of the ecosystem
microscopic consumer – herbivore (eats the producer)
producer (trapped sunlight & stored food) 5 5

6. name the producer, consumers & decomposers6 6

7. food web: more realistic path through an ecosystem made of many food chains7 7

8. 8 8

9. 9 9

10. food chain food web
(just 1 path of energy) (all possible energy paths)

11. each level in a food chain or food web is a trophic level
~ means “feeding level”
producers are ALWAYS the first trophic level
~ why called primary producers 11 11

12. this is how the sun’s energy enters the ecosystem
producers use most of the energy they make for themselves

13. energy NOT used by producers can be passed on to organisms that can’t make their own energy (consumers)

14. consumers that eat producers are primary consumers
~ first (primary) ones to consume (eat)
these are herbivores (plant eaters)
always make up the second trophic level 14 14

15. Some of the energy is lost into the atmosphere as heat.
Most of the energy the primary consumer gets from the producer is used by the consumer.
Some of the energy is lost into the atmosphere as heat. 15 15

16. This energy is available for another consumer.
Some energy in the primary consumer is stored – not lost or used by the consumer itself.
This energy is available for another consumer. 16 16

17. consumers that hunt & kill other consumers are called predators
animals that are hunted & killed are called prey
predator
prey 17 17

18. consumer that eats another consumer for energy is called a secondary consumer
~ is the second one to consume (eat)
may be a carnivore or a omnivore
may be a predator or a scavenger

19. copyright cmassengale
consumer that eats a consumer that already ate a consumer is called a tertiary (third level) consumer
may be a carnivore or a omnivore
may be a predator or a scavenger
copyright cmassengale 19 19

20. Each level depends on the one below it for energy!

21. “Rule of 10”
only 10% of the energy found in one trophic level is passed to the next level up
~ also known as the “10% Rule”
rest is used by the organism OR lost as heat
this limits the number of organisms that can be supported at each level

22. Ecological Pyramids
graphic representations of the relative amounts of energy or matter at each trophic level
may be:
~ energy pyramid
~ biomass pyramid
~ pyramid of numbers 22 22

23. E N R G Y Producers - Autotrophs Primary consumers - Herbivores
Tertiary consumers - top carnivores
Secondary consumers -small carnivores
Primary consumers - Herbivores
Producers - Autotrophs

24. Energy Pyramid 24 24

25. the amount of available energy decreases for higher consumers
energy pyramids show:
the amount of available energy decreases for higher consumers 25 25

26. amount of available energy decreases down the food chain26 26

27. biomass: amount of organic matter found in a group of organisms in an ecosystem
as you move up a food chain, both available energy and biomass decrease
energy is transferred upwards but is diminished with each transfer

28. Biomass Pyramid 28 28

29. Pyramid of Numbers
shows the number of individuals at each level 29 29