Food Chain - Needham.K12.ma.us

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Food Chains
Food Webs
Energy Pyramids
The movement of energy through an ecosystem
can be shown in diagrams called food chains.
The sun begins the food
chain because in most
ecosystems, the sun is
the original source of
energy.
Notice that the arrows
point in the direction
that the energy (the
food) is moving.
Food Chain
A food chain
is a simple
model of the
feeding
relationships
and energy
transfer in an
ecosystem.
Trophic Levels
Trophic levels are the “steps” in a food chain,
moving from producers to the different levels of
consumers.
Food Chain
The first organism in a food
chain is always a producer.
They make their own food.
The primary consumer is the
1st level of consumers. They
are usually herbivores.
The secondary consumer is the
2nd level of consumers. They are
usually carnivores or omnivores.
The tertiary consumer is the
3rd level of consumers. Usually
carnivores.
The quaternary consumer is the
4th level of consumers. Usually
carnivores.
Pond Food
Chain
Terrestrial
and Land
Food
Chains
Terrestrial
(Land)
Food Chain
In which
direction is the
energy moving
(up or down)?
Marine
(Ocean)
Food Chain
Mountain Food Chain
For example, shrubs are foodThe
formountain
deer,lion is
the second
consumer
and deer are food for mountain
lions.
of the food chain. It
eats the deer. It is the
secondary consumer.
Shrubs are the
beginning of the food
chain. They use
sunlight to perform
photosynthesis,
making them
producers.
The deer is the first
consumer of the food
chain; it eats the
shrub. It is the
primary consumer.
Ocean Food Chain
large fish
Human
Pike
Algae
Perch
Mosquito
larvae
Dragonfly
larvae
Food
Chain
with 6
levels
Creating a Food Chain
• A food chain is a series of events in which one
organism eats another and obtains energy.
• To create a food chain, start with the energy
source (in most cases, the sun).
Next
• Put in the producer- the first organism (living thing)
in the food chain
• Arrows are used to show the flow of energy from
one organism to another. The arrow always goes
from left to right.
• Then add the other organisms that feed off each
other.
Create a food chain from this
ecosystem.
Phytoplankton
(algae)
bass
snapping
turtle
Can you create a food chain from this
ecosystem? What’s missing?
A Food Web is a network of many food chains that shows
how energy is transferred within an entire ecosystem
The arrows
point in
the
direction
in which
the energy
(the food)
is moving.
Lake
Ecosystem
We can show the relationships between populations
in an ecosystem with the help of a Food Web
What would happen in this ecosystem if chemicals
poisoned many of the hawks?
There will be
nothing to eat the
snakes, so their
numbers will
increase.
All the frogs
get eaten
No frogs.
More
crickets
Most of the
cattail gets
eaten by the
crickets
The number of crickets
increases, so the number
of shrews goes up as well.
Now the crickets don’t have
enough food so their numbers go
down. Plus, the shrews are eating
up the crickets.
..and so on. The numbers of each species have an
effect on the numbers of the other species in the web.
Predict What Will Happen
Use the food web worksheet to predict what might
happen in the following situations:
A) There is very little rain and much of the Marsh
Grass and Cattail die off.
B) Humans nearby bring cats into the area.
C) The frogs eat some poisoned slugs from a
garden.
D) Coyotes move into the area. Coyotes eat snakes,
shrews, frogs and grasshoppers.
Diagram that shows the
amount of energy
available at each trophic
level of an ecosystem
Trophic
Levels
Trophic Levels
The Trophic level is the position the organism
holds in a food chain.
Examples: Producer, Primary Consumer, Secondary
Consumer, Tertiary Consumer, Quaternary Consumer
Energy Pyramid
diagram that shows the amount of energy available
at each trophic level
What do you
notice
happening as
you go from
the bottom to
the top of the
energy
pyramid?
Energy Pyramid
Only About 10% of the Energy in Organisms of
One Trophic Level Is Captured by Organisms of
the Next Level
What do you think happened to the rest of the energy?
It got used while the organism was alive. It
takes energy to live! An organism uses energy
to:
•
•
•
•
Move around and get food
Reproduce
Keep its heart beating & lungs breathing
Keep itself warm (keep its body
temperature up)
• Escape predators
Some was lost as waste (pee, poop, sweat)

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