Introduction to
ENERGY FLOW
ECOSYSTEMS
and
FOOD CHAINS
What is an ecosystem?
 Habitat
– place where an organism
lives.
 Population – group of organisms
from the same species.
 Community – group of organisms
from several species.
 Ecosystem – a community and all
of the physical aspects of a habitat.
Ecosystem
Community
Population
Organism
Ecology
 The
scientific study of interactions
between organisms and their
environments.
Biotic Factors
 All
living organisms that inhabit an
environment.
 Ex: animals, plants, protists…
Abiotic Factors
 All
nonliving factors in the
environment.
 Ex: air currents, temperature,
moisture, light, and soil
the ultimate energy source is the
SUN!!!
sun eclipse with palm
Energy Flow
 How
does the sun’s energy
enter the biological world?
PHOTOSYNTHESIS
Energy Flow
 The
sun’s energy flows into
organisms that can change the
sunlight into food then into
organisms that eat them.
 This flow is:
sunlight
producer
consumer 1
consumer 2
PRODUCERS
Producers make their own food.
They can also be called autotrophs.
 Ex. Plants, algae and some
bacteria

sunlight
producer
consumer 1
consumer 2
CONSUMERS
Consumers eat something
else. They also are called
heterotrophs.
 Examples: deer, rabbits, cows,
mice, lions, humans, hawks,
snakes

sunlight
producer
consumer 1
consumer 2
HERBIVORES
 Herbivores
eat
plants.
 They
can be called primary
consumers
 Ex. Cows, caterpillars, bunnies
sunlight
producer
consumer 1
Or primary consumer
consumer 2
Or secondary consumer
CARNIVORES
 Carnivores
eat meat and can be
called secondary consumers.
 Ex.
sunlight
tigers, wolves, snakes, hawks
producer
consumer 1
consumer 2
TOP CARNIVORES

A “top” carnivore is a tertiary
consumer. They are at the top of
the food chain.

Ex. whale eating a sea lion
or hawk eating a snake.
consumer 3
sunlight
producer
consumer 1
consumer 2
OMNIVORES
 Omnivores
eat meat and
plants.
 They are considered
secondary consumers.
 Ex. bears and humans
Where do all
the dead things go?
 They
are eaten.
YUMMMM!
 They
decay.
SMELLY!
What’s the difference?
Is it just a matter of taste?
Detritivore vs
Decomposers
 DETRIVORES:
 feed
on the remains of dead
plants and animals and other
dead matter (detritus)
 Crabs,
mites,
earthworms, snails
Detritivore vs
Decomposers
 DECOMPOSERS:
 break
down dead organic matter
 Bacteria
& fungi
“RECYCLERS”
They break down and release
nutrients from dead matter
back into the environment
Detritivores and
Decomposers
 Why
would they be called the
environmental “recyclers”?
decomposer
consumer 3
sunlight
producer
consumer 1
consumer 2
Food Chains & Food Webs
 Organisms
in ecosystems transfer
energy from organism to organism
in a graphic organizer known as
trophic levels.
producer
1
consumer 1
consumer 2
consumer 3
2
3
4
The Path of Energy
 ARROWS
on a food chain describe
this path of energy.
 Notice that the arrows point from
the organism being eaten to the
organism that is eating it.
producer
consumer 1
consumer 2
consumer 3
Food Chains & Food Webs
 Energy
is “lost” at each trophic
level as a result of the activities of
the organisms such as
metabolism.
 Only 10% of the energy is actually
passed on to the next level.
producer
consumer 1
consumer 2
consumer 3
Food Chains & Food Webs
 What
vital “recycler” is not shown
in this food chain?
producer
consumer 1
consumer 2
consumer 3
Food Chains & Food Webs
 If
all of the snakes in this chain died,
what would happen to the hawk?
 To the decomposers?
decomposer
producer
consumer 1
consumer 2
consumer 3