LO: SWBAT define ecological pyramid
and explain its relationship to energy in
an ecosystem
DN: Where does all of the energy in an
ecosystem come from? Explain.
HW: Article #2 due tomorrow
Ecological Pyramids
A diagram that shows the relative
amounts of energy in different trophic
levels in an ecosystem.
Which trophic level is the largest?
Producers
Why?
Energy Pyramid
2’ Consumers
1’ Consumers
Producers
Energy Flow
3’ Consumers
What does an ecological pyramid
show?
1. Energy
2. Biomass
3. Number of organisms in a food
web
Ecological Pyramids show that the
energy, biomass, and numbers at any
trophic level are less than those of the
trophic level below it.
Section 3-2
Ecological pyramids
Energy Pyramid
Biomass Pyramid
Go to
Section:
Pyramid of Numbers
Sun’s Energy in an Ecosystem
• Some of the
energy is
used by each
organism and
some of it is
lost as heat
energy to the
environment
Energy Pyramid
• Shows the relative amount of energy
available at each trophic level.
• Organisms use about 10 percent of this
energy for life processes.
• The rest is lost as heat.
Why is there so little energy at
the top of the pyramid?
• Most of the energy from the sun has been used
or lost by organism in the lower levels
• Only about 10% of the energy available at each
level is transferred to the NEXT level.
1%
10%
100%
Biomass Pyramid
• Represents the amount of living
organic matter at each trophic level.
• Typically, the greatest biomass is at
the base of the pyramid.
Pyramid of Numbers
Shows the relative number of individual
organisms at each trophic level.
1. What is biomass?
2. Why isn’t all of the energy that enters
organisms available to the next trophic
level?
3. What three things are ecological
pyramids used to represent?
4. From where is the energy in most
ecosystems derived?
5. How does the energy, biomass, or
population at each trophic level
compare to that of the level below it?
1. Biomass is the total amount of organic
matter present in a trophic level.
2. Much energy is lost when organisms use it
to generate heat and power movements.
3. An ecological pyramid is used to show
energy, biomass, or the number of
organisms in a food web.
4. Energy in most ecosystems comes from the
sun.
5. Pyramids of energy, biomass, and numbers
(population) show that the energy, biomass,
and numbers at any trophic level are less
than those of the trophic level below it.