Grade 7 Science: Interactions in the
Environment
Ms. Willis
The Roles of Organisms

 Learning Goal:
 Describe the roles and interactions of producers,
consumers and decomposers within an ecosystem.
 Understand and use appropriate science and
technology vocabulary (producer, herbivore,
carnivore, omnivore, scavenger, detrivore,
decomposer)
 Success Criteria:
 I can explain how producers, consumers, and
decomposers play critical roles in an ecosystem.
The Roles of Organisms

 Introduction:
 You play an important role in your family and/or
community.
 Organisms play critical roles in ecosystems.
 An organism’s role within an ecosystem depends on
how it obtains its food.
 Organisms are divided into three categories:
 1. Producers
 2. Consumers
 3. Detrivores and Decomposers
Producers

 Plants produce their own food through
photosynthesis, so are called producers (def next slide).
 Photosynthesis: Plants use energy from the sun,
water from the soil and carbon dioxide from the air
to make food in the form of sugar (glucose).
Producers

 Definition of a producer:
An organism that
makes its own
food from nonliving (abiotic)
materials.
Consumers

 Animals cannot make their own food. They must
obtain their energy from eating other organisms.
Consumer: An organism that eats
other living things for energy.
 Examples?
Types of Consumers

 Herbivores:
 An organism that eats only plants
 Carnivores:
 An organism that eats other animals only
 Omnivores:
 An organism that eats both plants and animals
 Scavengers:
 An organism that eats already dead animals
What are some more examples of each?
Detrivores and
Decomposers

 Have you ever wondered where all the dead
organisms go (think of fallen leaves, other dead
plants, animal carcasses, etc.). If there was not some
way of disposing these, Earth would soon be covered
with dead things!
 This is where detrivores and decomposers come in!
They are very important components of every
ecosystem!
Detrivores and
Decomposers

 Detrivore: An organism that feeds on large parts of
decaying plant and animal matter and on waste
material.
 Detrivores leave behind their own waste material
and small pieces of decaying plants and animals.
Now decomposers takeover!
Detrivores and
Decomposers

 Decomposer: An organism that consumes and
breaks down dead organisms or waste matter into
simple substances/nutrients.
 Decomposers feed on any remaining decayed matter
and waste left behind by consumers and detrivores.
Examples: bacteria, fungi (mould)
Detrivores and
Decomposers

Let’s watch some detrivores and decomposers
at work (get ready for close ups of creepy
crawlies and slime!):
Decomposers
The Roles of Organisms
in an Ecosystem

Review this lesson with a partner: Complete
the given six-column chart, describing how
each type of organisms obtains food. Compare
ways in which they are the same and different.