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Chapter 3
Ecology
Energy Flow
• Ecology is the study of
the way living things
interact with each other
and their physical
environment.
How does energy flow?
•Energy flows in one direction.
From sun to the producers to the
consumers
•Producers (plants)=
organisms that make their
own food to obtain energy
•Consumers( animals)=
organisms that consume
other organism for energy
•Heat Energy (sun) is
converted to Chemical
Energy (food) through
energy flow.
•Some energy is lost to heat
at each transfer
Producers
Organisms that use energy
from the environment (make
their own food) through
sunlight or chemicals are
called autotrophs or
PRODUCERS.
•The main source of
energy for life on
Earth is the SUN.
•Organisms use sunlight
through photosynthesis.
•Photosynthesis is the use
of light energy to power
chemical reactions that
convert carbon dioxide
and water into oxygen and
carbohydrates like sugar
and starch.
• On land, plants are the main autotroph.
In freshwater ecosystems and the sunlit
upper layers of the ocean, algae are the
principal autotrophs.
Cyanobacteria
• Photosynthetic
bacteria are the
most common
and produce
much of the
earth’s oxygen.
• Some autotrophs rely on stored
energy found in inorganic
chemical compounds instead of
the sun.
• Since they get their energy from
chemicals, they are called
chemotrophs and use
chemosynthesis to produce
carbohydrates.
• Chemosynthesis is
performed by several
types of bacteria.
These bacteria can be
found in obscure places
like:
•Volcanic vents on
the ocean floor.
Hot Springs & Tidal
Marshes along the coast.
• Organisms that cannot harness
energy directly must acquire
energy from other organisms
and are called consumers or
heterotrophs.
• There are many different kinds
of heterotrophs:
Herbivores only eat plants.
Prey
Carnivores only eat meat
Predator
Omnivores eat plants & meat
Detritivores
• Mites, earthworms, snails, and crabs
feed on plant and animal remains and
other dead matter, called detritus.
Decomposers (Saprophytes)
break down organic matter.
What are some ways we can see how
energy is transferred?
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Ecological Food Chains and Webs
Ecological Pyramids
Energy Pyramids
Biomass Pyramids
Numbers Pyramids
• Energy flows through an ecosystem in
one direction, from the sun or inorganic
compounds to autotrophs (producers) and
then to various heterotrophs (consumers).
Food Chain
• Series of steps in which organisms
transfer energy by eating and being
eaten.
Food Chain
What are the producers in this chain?
What are the secondary consumers?
Where is the least energy in this chain?
What type of feeding organism is the squid?
• Food Webs are the feeding
relationships among the different
organisms in an ecosystem.
• Each step in a food chain or food
web is a trophic level.
Food Chains and Webs
•Producers are at the
beginning(photosynthetic
organisms)
•Herbivores (primary consumersget energy only from plants
(grasshopper)
•Carnivores (secondary/tertiary
consumers-feed on other animals
(owl)
•Omnivore= organism that feeds
on both plants and animals
•ARROWS INDICATE THE
TRANSFER OF ENERGY
•The most of the energy is at the
producer level. Least is at the top
level
•Trophic Levels: each step in a
food chain or web
Ecological Pyramids
• A diagram that shows the relative
amounts of energy or matter contained
within each trophic level in a food
chain or food web.
• Only 10% of the energy available
within one trophic level is transferred
to organisms at the next trophic level.
Ecological Pyramid
Energy Pyramid
• shows the relative
amount of energy at
each trophic level
•Average energy
transfer form one
trophic level to the
next is 10%
Biomass
Pyramid
Pyramid of
Numbers
•Shows the total
amount of living
tissue within
trophic level
•Shows the relative
number of
organisms at each
trophic level
•Highest quantity
on the bottom
lowest on the top
Biomass
• The total amount of living tissue within a
given trophic level.
• A biomass pyramid represents the amount
of potential food available for each trophic
level in an ecosystem.