ENERGY FLOW and
COMMUNITY INTERACTIONS
Chapter 2; pages 31 - 49
ENERGY FLOW
•What is an ecosystem?
•It is a self supporting unit of interacting
organisms and their environment.
ENERGY FLOW
• Ecosystems have 4 characteristics:
•Capture energy and store it in
glucose (photosynthesis)
•Transfer energy (respiration)
•Decompose
•Recycle/Reuse
THE ULTIMATE SOURCE OF ENERGY
THE SUN
CAPTURE AND STORE
ENERGY
• The sun’s energy can be captured and
stored in glucose through photosynthesis.
ENERGY
TRANSFER ENERGY Pages 41-44
• Organisms in ecosystems transfer energy
from organism to organism
• Energy is transferred in a linear chain
• What part of the food chain shows the
transfer of energy?
FOOD CHAIN
sunlight
TRANSFER ENERGY
• Can you identify?:
– Producers (autotrophs)
– Consumers (heterotrophs)
– Herbivores (heterotrophs)
– Carnivores (heterotrophs)
– Omnivores (heterotrophs)
sunlight
FOOD CHAIN
TRANSFER ENERGY
• Interacting food chains are known as a
food web.
TRANSFER ENERGY
• Food chains can be shown as trophic
levels (level at which an organism
feeds)
4TH CONSUMERS
3RD CONSUMERS
2ND CONSUMERS
PRIMARY CONSUMERS
PRODUCERS
DECOMPOSE
• Where do all the dead things go?
•They are eaten.
Yummmmm!
•They decay.
Smelly!
DECOMPOSE
•Detritivore
•Feeds on the remains of dead
plants and animals and other
organic matter
•Decomposers
•Breaks down dead organic
matter.
•Bacteria and
fungi are
decomposers
DECOMPOSERS
decomposer
consumer 3
sunlight
producer
consumer 1
consumer 2
Ecological Pyramids
• Instead of
representing
trophic levels in a
food web, an
ecological
pyramid can be
used.
ECOLOGICAL PYRAMIDS
• What do the big
numbers represent?
3
• What does the
kcal mean? 2
1
4
Hawk
(10 kcal)
Snake (100 kcal)
Mouse (1,000 kcal)
Grass (10,000 kcal)
PYRAMID OF ENERGY
• How does a pyramid of energy compare to
a food chain?
1
2
3
4
3
2
1
sunlight
FOOD CHAIN
4
PYRAMID OF ENERGY
• On what trophic level would a primary
consumer appear?
1
2
3
4
sunlight
PRIMARY CONSUMER
PYRAMID OF NUMBERS
•What information would
this pyramid include if it
were a pyramid of
numbers?
•How do they get a
number total for a
population of
organisms?
PYRAMID OF BIOMASS
•What is biomass?
•What information would
this pyramid include if it
were a pyramid of
biomass?
•Compare the population
size of the hawk to
the population
size of the
grass?
RELATIONSHIPS IN
ECOSYSTEMS
COMPETITION,
PREDATOR/PREY, AND
SYMBIOTIC RELATIONSHIPS
Pages 39-40
Competition
humans
COMPETITION
plants &
animals
Organisms living in the same place at the
same time must compete for natural
resources (food, water, shelter, space)
Predation
Predator
• Interaction in which one
organism
captures and feeds on
another organism
Prey
Predation
• Rabbit and Coyote
rabbit
coyote
Ultimate Predator?
• Why is man sometimes
called the “Ultimate
Predator”?
Symbiotic Relationships
•An ecological relationship in which two
or more species lives in a close, long
term association
•There are 3 types of
symbiotic relationships
•Mutualism
•Commensalism
•Parasitic
Mutualism
• Relationship in which both species
benefits
termites
Termites cannot digest
wood. Protists live in
the guts of termites
and digest the wood.
Both are happy!!!
Protozoans in termite gut
Joseph Leidy lithograph,
1891
Mutualism
Lichen –
an algae
and a
fungus
living
together.
The algae receives
protection and the
fungus receives
glucose.
Photos by permission of
Steve and Sylvia Sharnoff
Commensalism
• Relationship in which one organism benefits
and the other is neither helped nor harmed.
Parasitism
•Relationship in which one
organism benefits and the
other organism is harmed.
Ticks, Fleas, Worms on a
Dog: Parasite gets
nourishment from the dog.
The dog is harmed…may
become sick from the bite
or disease.
(Parasites and Parasitological
Resources)