Trophic Levels,
Energy transfer
and Pyramids
Vocabulary
 Trophic
Levels – is the position an
organism occupies in a food chain. It
refers to food or feeding.
 Apex
predator – top level predators with
few or no predators of their own.
Food Chain
Food Chains
 The
energy flow from one trophic level to the
other is know as a food chain
 Producers are at the first TROPHIC LEVEL
 Primary Consumers are the SECOND TROPHIC
LEVEL
 Secondary consumers are at the THIRD
TROPHIC LEVEL
Trophic Levels (feeding levels)
3
2
1
Food Web
 Most
organisms eat more than JUST
one organism
 When
more organisms are involved
it is know as a FOOD WEB
 Food
webs are more complex and
involve lots of organisms
Food Webs
Food webs show
ALTERNATIVE PATHWAYS
other possible pathways
through which an
organism can obtain
energy
Food webs
Trophic Level
Grass
Mouse
Grasshopper
Frog
Owl
Hawk
Producer, primary
consumer, secondary
consumer, tertiary
consumer?
Trophic Level
Producer, primary
consumer, secondary
consumer, tertiary
consumer
Producer
Grass
1st
Mouse
2nd
Primary consumer
Grasshopper
2nd
Primary consumer
Frog
3rd
Secondary
consumer
Owl
3rd and 4th
Hawk
3rd
Secondary and
tertiary consumer
Secondary
consumer
Transfer of Energy
 When
a lion eats a zebra, it does
not get all of the energy from the
zebra.
 Energy
 Energy
lost is usually in form of heat
lost from chain “link” to “link”
is significant!
from grass to sheep, loss is about
90%!
HEAT
90%
HEAT
90%
100% Energy
Available
10% Original
Energy!
1% Original
Energy!
Energy lost from one trophic level
(energy level) to the next level can be
represented by a pyramid
4⁰
CONSUMERS
3
CONSUMERS
2 CONSUMERS
1 CONSUMERS
PRODUCERS
Each level above only gets 10% of the
energy from below
Ex: 10,000 J of producers (plants) only give 10% of
energy to primary consumers
1,000 J to primary consumers (snails,
minnows, dragonflies)
100 J to secondary consumers (small fish)
10 J to tertiary consumers (big fish)
1 J to quaternary consumers (fish hawk)
ENERGY PYRAMID
1J
10 J
100 J
1,000 J
10,000 J
Energy Pyramid
 Three
hundred trout are needed to
support one man for a year. The trout, in
turn, must consume 90,000 frogs, that
must consume 27 million grasshoppers
that live off of 1,000 tons of grass.
-- G. Tyler Miller, Jr., American Chemist
(1971)
Usually
no more than 5 trophic
levels since 6th level would have
very little energy to keep it alive
Ecological Pyramid
•
•
•
•
Which
Which
Which
Which
level
level
level
level
has
has
has
has
the
the
the
the
most energy?
most organisms?
least organisms?
least energy?
Pyramid of Numbers
• Shows the numbers of individual organisms at each
trophic level in an ecosystem.
tertiary
consumers
5
secondary
consumers
5000
primary
consumers
500,000
producers
producers
5,000,000
• A vast number of producers are required to support even a few
top level consumers.
Biomass pyramid
• Biomass is a measure of the total dry mass of
organisms in a given area.
tertiary
consumers
75 g/m2
150g/m2
secondary
consumers
primary
consumers
producers
producers
675g/m2
2000g/m2