An ecosystem
is all the
organisms in a
geographical
area, and all
the physical
characteristics
of that area as
well. (biotic,
and abiotic
factors)
Name one abiotic factor in this tadpole’s ecosystem.
1. Producers
2. Consumers
3. Decomposers
Producers are also known as
autotrophs
Organisms that make
their own food
through
photosynthesis and
chemosynthesis
Photoautotroph/Chemoautotroph
2. Consumers
Also known as heterotrophs
Organisms that rely
on other organisms
as food sources to
get energy
3. Decomposers
Some consume dead organisms and their waste,
producing detritus. Some consume detritus, and
are called detritivores. Many are microorganisms,
but some are multicellular.
Organisms that use chemicals to make their
own food are called…
What is detritus?
What is the ultimate source of energy for
most organisms on Earth?
What is the scientific name given to
consumers?
Herbivores
Eat producers only.
Omnivores
Eat producers, herbivores,
carnivores, and other
omnivores
Carnivores
Eat only other animals
Scavengers
Do not eat living prey, but instead find dead organisms that have
been preyed upon by other carnivorous consumers.
Facultative Heterotrophs
Carnivorous plants
can produce the
carbohydrates they
need through
photosynthesis…but
they typically live in
bogs, where the soil
is very wet, and
nutrients, like
nitrogen get washed
away. They consume
insects and even
small vertebrates to
obtain the required
nitrogen.
What is the difference between a scavenger
and a decomposer?
Why have some plants adapted to become
facultative heterotrophs?
In what biomes might you find facultative
heterotrophs?
All energy on Earth comes ultimately from the sun. A model of
energy flow in ecosystems is called a food web. It shows how
matter and energy moves from producers to consumers, and
finally to decomposers. Please note, the arrow points to the
consumer in any food chain, or web! Decomposers are very
easy to accommodate, as
they will fit into any
trophic level.
A trophic level is one
step, or link in a food
chain.
This food web contains
many food chains.
Do not confuse trophic level, with consumer level!
The second trophic level is filled by the primary
consumer…the third trophic level is filled by the
secondary consumer…etc.
When describing a
food chain, you always
begin with an
autotroph… or a
producer. Since they
are the first trophic
level, they are often
referred to as
primary producers.
The second trophic
level is filled by the
primary
consumers…and they
are consumed by the
secondary consumers,
who are consumed by
the tertiary
consumers, who are
consumed by the
quaternary
consumers…if there is
any energy left!
Energy "flows"
through the
ecosystem in the
form of carboncarbon bonds. When
respiration occurs,
the carbon-carbon
bonds are broken
and the carbon is
combined with
oxygen to form
carbon dioxide.
This process releases the energy, which is either used by the organism (to
move its muscles, digest food, excrete wastes, think, etc.) or the energy
may be lost as heat. Note that all energy comes from the sun, and that the
ultimate fate of all energy in ecosystems is to be lost as heat. Energy does
not recycle!! This follows the 2nd Law of Thermodynamics…or Entropy.
The other component shown in the diagram are the inorganic
nutrients. They are inorganic because they do not contain
carbon-carbon bonds.
The movement of the inorganic
nutrients is represented by the
open arrows. Note that the
autotrophs obtain these
inorganic nutrients from the
inorganic nutrient pool, which is
usually the soil or water
surrounding the plants or algae.
These inorganic nutrients are passed from organism to
organism as one organism is consumed by another.
Ultimately, all organisms die and become detritus, food for
the decomposers. At this stage, the last of the energy is
extracted (and lost as heat) and the inorganic nutrients are
returned to the soil or water to be taken up again. The
inorganic nutrients are recycled, the energy is not.
In the flow of energy and inorganic nutrients through
the ecosystem, a few generalizations can be made:
• The ultimate source of energy (for most
ecosystems) is the sun
• The ultimate fate of energy in ecosystems is for it
to be lost as heat.
• Energy and nutrients are passed from organism to
organism through the food chain as one organism
consumes another.
• Decomposers remove the last energy from the
remains of organisms.
• Inorganic nutrients are cycled, energy is not
What is the one exception to this?
How does energy flow through
ecosystems? (ie How is energy stored?)
What process is responsible for “freeing”
the energy in these bonds?
In what trophic level does the secondary
consumer lie?
Which law of thermodynamics does the
energy in a food chain follow?
In Moodle,
use this
complex
Antarctic
Food Web,
and
diagram 3
possible
food
chains in a
flow map.
Select
chains that
go at least
to the
quaternary
consumer.