1) Organisms in an ecosystem can be producers, consumers, or decomposers. Producers like plants generate their own food through photosynthesis. Consumers cannot make their own food and eat other organisms, including primary, secondary, and tertiary consumers. Decomposers break down dead organisms. 2) Food chains show the transfer of energy as organisms eat each other. Producers are first, then primary, secondary, etc. consumers. Food webs show overlapping food chains and how organisms can play different roles. 3) Energy pyramids illustrate the loss of energy at each trophic level, with 10% transferred to the next level and 90% used for life processes.

1. Food Chains and Food
Webs
Energy Flow in Nature

2. Energy Roles
•An organism’s energy
role in an ecosystem
may be that of a
producer, consumer, or
decomposer.

3. Eat or be eaten
1. Producer (autotroph)
– can make its own food by
converting the Sun’s energy
into chemical energy through
photosynthesis
– Source of all food in the
ecosystem
Ex: terrestrial and aquatic
plants, algae

4. Mmmmm…delicious.
2. Consumer (heterotroph)
– cannot make its own food so must eat other organisms to
get energy
There are several words that describe consumers…
– Primary Consumer: eat producers
Ex: caterpillar
– Secondary Consumer: eats primary consumers
Ex: robin
– Tertiary Consumer: eats secondary consumers
Ex: hawk

5. More Consumer Terms
– Herbivore: eats plants (primary
consumer)
Ex: beetle
– Carnivore: eats animals
Ex: wolf
– Omnivore: eats both plants and animals
Ex: bears, racoons, humans
– Predator: feed on live animals
– Prey: animals that the predator
catches and eats

6. Hey, you gonna eat that?
3. Decomposer
– Uses enzymes (chemicals) to break down
dead organisms and releases nutrients to
ecosystem
Ex: bacteria, maggots, fungi, worms

7. Food Chains
•Series of events where one
organism eats another and
obtains energy.
•First organism in chain is
the producer.
•The second organism is the
consumer that eats the
producer.

8. Come up with an example to fill in
the blocks of a food chain in an
ecosystem.

9. Food Web
•Consists of many
overlapping food chains in
an ecosystem.
•Some organisms may play
more than one role by
changing consumer levels.

10. Food webs
• All organisms need FOOD to survive!
• Food webs show what eats what.

11. What happens in a food web if
one or more of the organisms
disappear?

12. Which
animals are
carnivores
and
herbivores?

13. Energy Pyramids
• A diagram that shows the
amount of energy that moves
from one feeding level to
another in an ecosystem.
• Represented in a triangle
with the most energy at the
producer level.

14. An Energy Pyramid

15. Energy Loss and Use
• 10% of energy is transferred to next
higher level.
• 90% of energy is used by organisms’
life processes.
• Due to energy loss, ecosystem cannot
support many feeding levels.
• The more levels in an energy pyramid,
the less energy is left for the top
consumer from the original producer.

16. There is an energy loss as you move
to a higher level in the energy
pyramid.