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Roles of Organisms in
Ecosystems
Essential Questions
• What are the energy roles of organisms in
an ecosystem?
Energy Roles
• An organism’s energy role is determined
by how it obtains or gets energy and
interacts with other organisms within an
ecosystem.
• Each organisms in an ecosystem fills the
energy role of producer consumer, or
decomposer – this is it’s niche.
Producers and their Niche
• An organism that can make its own food is
a producer.
• Energy enters most ecosystems as
sunlight, which plants, algae and some
bacteria use to make their own food
(photosynthesis).
• Producers are the source of all food in an
ecosystem.
• Think about it – have you ever had to give
a plant half of your lunch because it was
starving?
Consumers and their Niche
• Consumers cannot make their own food
and therefore get food by feeding off of
other organisms.
• Compare and Contrast: How are
producers and consumers similar and
different?
• Consumers are classified by what they
eat. They can be herbivores, carnivores or
omnivores.
Herbivores
• Herbivores are consumers that get their
energy from eating only plants.
• Can you think of some herbivores?
Omnivores
• Omnivores are consumers that get energy
from eating both plants and animals.
• Bears, humans and ____________ are
omnivores.
Carnivores
• Carnivores are consumers that eat only
animals.
• Lions and spiders are some examples of
carnivores.
Decomposers and their Niche
• Decomposers break down wastes and
dead organisms and return nutrients to the
ecosystem.
• Earthworms, mushrooms and bacteria are
decomposers.
• Is the niche of a decomposer important?
Paparazzi!!
• Looking for producers, consumers and
decomposers in our ecosystem!
• Grab your science notebooks, your pencils
and I’ll grab my camera as we go on a
hunt for organisms in our ecosystem.
Energy Flow in Ecosystems
Energy Flows Through
Ecosystems
• The Sun’s energy can flow through an
ecosystem.
• As the Sun’s energy enters most ecosystems it
is converted into food by producers.
• This energy is transferred to each organism that
eats a producer and then to other organisms
that feed on these consumers.
Food Chain and Webs
• The movement of energy through an
ecosystem can be shown in diagrams
called food chains and food webs.
• A food chain is a series of events in
which one organism (predator) eats
another (prey) and obtains energy.
• It shows one possible path that energy can
flow.
Levels in a Food Chain
• All food chains have different levels of
consumers.
Producer
First level
consumer
Second
consumer
A Food Web
• Do you eat the same thing every day?
• A Food Web is a combination of many food
chains.
• Consumers and producers belong to many
different food chains.
Red arrows show
energy moving from
second-level consumers
to third-level consumers.
Yellow arrows show
energy moving from
first-level consumers to
second-level consumers.
Blue arrows show the
movement of energy
from producers to
first-level consumers.
Producers form the base
of the food web.
Decomposers consume
the wastes and remains
of other organisms.
Bacteria
Energy Pyramid
• A diagram called an energy pyramid
shows the amount of energy that moves
from one feeding level to another in a food
web.
• The most energy is available at the
producer level of the pyramid. As you
move up the pyramid, each level has
less energy available than the level
below.
• Why do you think this happens?
Third-Level Consumers (1 kcal)
Second-Level Consumers (10 kcal)
First-Level Consumers (100 kcal)
Producers (1,000 kcal)
Energy Pyramids
• When an organism in an ecosystem eats,
it obtains energy. The organism uses
some of this energy to move, grow,
reproduce, and carry out other life
activities.
• This means that only some of the energy it
obtains will be available to the next
organism in the food web.
What Eats What?
• In your groups research a food chain that
exist within each type of ecosystem below:
•
•
•
•
Ocean
Forest
Desert
Wetland
• Use a flow chart to show your work.
• There are books and computers for you to
use!