This document discusses energy flow through ecosystems. It defines three main roles: producers, which make their own food through photosynthesis; consumers, which obtain energy by eating other organisms; and decomposers, which break down waste and dead organisms, returning nutrients to the environment. Food chains show a single path of energy transfer between organisms, starting with a producer and moving up through consumer levels. Food webs depict the many overlapping food chains in an ecosystem. Energy pyramids illustrate that only about 10% of energy is transferred between trophic levels, with most energy being lost as heat.

1. Energy Flow in Ecosystems
Food Chains & Food Webs

2. 3 Roles
• Producer – Makes its own food
– usually plants or one-celled organisms
– Algae
– Phytoplankton, tiny organisms that live in
the ocean
– Some types of bacteria
• Consumer – Obtains energy from eating other
organism
– Omnivore, herbivore, carnivore, scavenger
• Decomposer – Break down wastes and dead
organisms and return the raw materials to the
environment
– fungi and bacteria

3. Organisms that
make their own
food are
producers.

4. Organisms that depend on
others for food are consumers.
• Herbivores -
plant eaters

5. Carnivores - meat eaters

6. Omnivores - plant and meat eaters

7. Scavengers - feed off dead organisms

8. Organisms that break down
wastes and dead organisms &
return the raw materials to
the environment are
decomposers.

9. Decomposer

10. Food Chain
• A series of events in
which 1 organism
eats another and
obtains energy
• Shows 1 possible
path along which
energy can move

11. Food Chain
• Arrows point in the
direction of the
organism that is
eating the other. It
means “Is eaten by”
• Arrows also show the
direction of energy flow.

12. Food Chain
• 1st organism always a producer
• 2nd organism is a primary consumer that
eats the producer – 1st level consumer
(primary consumer)
• 2nd level (secondary) consumer eats the
1st level consumer
• 3rd level consumer (tertiary) feed on
secondary consumers

13. Food Chain
• Position in the food chain is
related to size.
• Larger organisms are normally
further up the food chain than
smaller organisms

15. Food Web
• A more realistic way to show
energy flow in an ecosystem
• Shows many overlapping food
chains in an ecosystem

16. Energy Pyramid
• A diagram that shows
the amount of energy
that moves from 1
feeding level to
another in a food web
• At each level Energy is
lost
• Only about 10% of
the energy in 1 level is
transferred to the
next level
Where does the energy go?

17. 1st level
consumer
2nd level
consumer
plants
herbivores
carnivores
and
omnivores

18. Energy Pyramid
• MOST ENERGY IS AVAILABLE AT
THE PRODUCER LEVEL
• AT EACH LEVEL THERE IS LESS
AVAILABLE ENERGY THAN AT THE
LEVEL BELOW

19. Energy loss from Food Chain/Web
• Organisms use the energy they get
to survive:
– Movement
– Body heat
– Reproduce
– Carry out Chemical Reactions
• Energy passed on is from growth.
• The bigger the organism eaten, the
more energy the next organism
gets.