Energy Flow in a Food
Chain/Webs
Energy
• Every living thing needs energy in order to
live
• Every time consumers do something (run,
jump) they use energy
• Plants get their energy from photosynthesis
• Energy is needed for living beings to grow
The Food Chain
• Brainpop - Food Chains
• A food chain shows how living thing gets
energy
• Energy is passed from creature to
creature
• Food chains begin with plant-life, and
end with animal-life.
• Arrows are used to represent energy
being passed
Different types of Food Chains
• There can be many links in food chains but
not TOO many
• If there are too many links, then the animal
at the end would not get enough energy
Food Chain with Decomposers
• Food chains make a full circle!
• Energy is passed from plant to animal
to animal to decomposer and back to
plant!
Food Web
• Is a bunch of food
chains in one
• Several
connections may
occur between
organisms
• Ex: Snake gets
energy from frogs
and rabbits
Lets see how well you understand
what we learned so far:
GAME
http://www.sheppardsoftwa
re.com/content/animals/ki
dscorner/games/foodchain
game.htm
Food Chain Reaction
A change in the size of one population
in a food chain will affect other
populations.
This interdependence of the populations
within a food chain helps to maintain the
balance of plant and animal populations
within a community.
Food Chain Reaction
http://www.ecokids.ca/pub/eco_info/topics/frogs
/chain_reaction/play_chainreaction.cfm
http://www.ecokids.ca/pub/eco_info/topics/frogs
/chain_reaction/play_chainreaction.cfm
http://puzzling.caret.cam.ac.uk/game.php?game=f
oodchain
Consumers that eat producers
to get energy:
• Are primary
consumers = FirstOrder
A consumer that eats another
consumer for energy:
• Is called a secondary
consumer= SecondOrder
A consumer that eats a consumer
that already ate a consumer:
• Is called a tertiary
consumer= Third-
order
A consumer that eats a consumer
that ate a consumer that already ate
a consumer:
• Is called a quaternary
consumer = Fourth-
Order
Transfer of Energy in a Food Chain
The transfer of energy (arrows)
1.
2.
3.
4.
5.
Sun to producer
To primary consumer
To secondary consumer
To tertiary consumer
To quaternary consumer
At the bottom of this page!
• Make a food web using the following
animals. (write words don’t draw)
• Include the Arrows showing energy.
Mountain Lion
Second-order
heterotrophs
Hawks
Snakes
Deer
First-order
heterotrophs
Mice
Rabbits
Seed Eating Birds
Autotrophs
Grass
Shrubs
Trees
Name__________________________
Date___________
Period__________
#_____________
Decomposers
ENERGY PYRAMID
Another way of showing the
transfer of energy in an
ecosystem
How is energy being used?
• Some of the energy is being used in the
consumer
• Some energy is lost as heat
• Some energy is stored and can pass on to
another consumer
How it works…
ECO-PYRAMIDS: The concept of a pyramid is useful to describe the
energy (trophic) levels of organisms, the amount of biomass, and
amount of energy transferred from one trophic level to another.
The base of a pyramid is the widest part. Producers are at the base of
the eco-pyramid. There are more producers than any type of organism
in an ecosystem. 100% of the energy captured from the sun is in the
base. There is much more biomass in the base than anywhere else in
the pyramid.
The second level up a pyramid is smaller than the base. Here is where
the primary consumers are placed. There are fewer primary consumers
than producers. There is only about 10% of the biomass that is found
in the base. Only 10% of the energy captured from the sun by the
producers is passed up to this level.
The third level up the pyramid is smaller than the second. Here is
where the secondary consumers are placed. There is only about 1% of
the biomass that is found in the bass (That's 10% of the biomass in
the level below it!). This level has only 1% of the energy that is
captured from the sun. (That's 10% of the energy in the level below
it!)
The fourth level is the last level. It is the last level because there is
not enough energy left to pass up to another level. This is the level of
the tertiary consumer. Only 0.1% of the energy captured by the
producers makes it up to this level. Only 0.1% of the biomass in the
ecosystem is contained in this level as well.
GENERAL PATTERNS IN THE ECO-PYRAMID:
"THE 10% RULE“
- Only 10 % of the energy from a level is passed up to the next level
- Only 10 % of the biomass from a level is passed up to the next level
There are always fewer individuals in the populations as you go up the
pyramid. The higher you go on the pyramid, the less energy is available!
How much energy is lost?
• At each level only 10% of the energy
available is passed on.
• 10% Rule Video clip
• Brainpop Energy Pyramid
Trophic Levels:
• The trophic level
is the position an
organism holds in a
food chain or web
1. Primary producer
2. Primary Consumer
3. Secondary
consumer
4. Tertiary Consumer
5. Quaternary
Consumer
1 Osprey
10 Northern Pike
100 Perch
1,000 Bleak Fish
10,000 kcal of plants
Your Turn!
• Use the notes to help you answer all the
questions about the relationships in food
webs, food chains and food pyramids.
• If you don’t finish it’s HOMEWORK!!!