Transcript 3 Food Webs - Solon City Schools

ENERGY FLOW:
Where does the Energy Go?
(fig 34.2, 34.3)
Laws of Thermodynamics…
1. Energy is neither created
or destroyed, only
transferred
 2. With every transfer,
some energy is lost to
HEAT (or other less
available form of energy)

A little vocab…

Autotroph- an organism that can make
its own food


Also called PRODUCERS
Heterotroph- an organism that cannot
make its own food and must obtain it
from eating
BIOTIC COMPONENTS of an
ECOSYSTEM
PRODUCERS
(produce food)
Chemoautotrophs- bacteria
that use inorganic chemicals
like ammonia, nitrites, sulfides
to make food)
Photoautotrophs-use energy
from the sun…produce most of
the organic nutrients for the
biosphere
CONSUMERS
DECOMPOSERS
(consume food)
Need a preformed souce of
organic nutrients
(Break down dead organic matter)
VALUABLE- release inorganic
nutrients for plants to take up
Consumers can be :
Primary/Secondary/
Tertiary
(See next)
Ex- nonphotosynthetic
bacteria, fungi
DETRITUS=
partially decomposed
matter in the water or
soil
What does
each arrow
represent?
Kinds of Consumers

All consumers are heterotrophs

ExamplesScavengers
 Primary/1st level
 Secondary/ 2nd level
 Tertiary/ 3rd level

Kinds of consumers continued…
Herbivore : Feed on grass and other
plantsPrimary Consumers
 Carnivore : Eat animals
 Carnivores that eat Herbivores 
Secondary Consumers
 Carnivores that eat other carnivores 
Tertiary Consumers
 Omnivore : Eat both plants and animals.

FOOD CHAINS…

Food Chains
show how
matter and
energy move
through an
ecosystem
A weakness in the chain…
Food chains can only have up to about 5
links … Why?
 because the animals at the end of the
chain would not get enough nutrients
and energy.
 So…most animals are part of more than
one food chain in order to meet their
requirements…
 This creates…

FOOD WEBS
Interconnected food chains.
 They express all the possible feeding
relationships at each trophic level in a
community.
 IMPORTANT POINT:
 Arrows are drawn from food source to
consumers (substitute “eaten by” for
arrows)

All food is NOT created equal…
TROPHIC LEVELS: All the organisms
that feed at a particular link in a food
chain
 10% rule: In general only about 10% of
the energy from one trophic level is
available to the next!!!

Biomass Pyramid

The total amount of living material
present in each trophic level (a feeding
step in a food chain).
NOTE: are there
more autotrophs
or heterotrophs?
WHY?
Pyramid of Numbers
Each bar in the pyramid
represents the size of the
populatoin at that trophic
level
Pyramids of Energy

Each bar in
the pyramid
represents
the energy
available
within that
trophic level
Which of the following organisms
are producers?
8.
9.
10.
5
11%
11%
5%
5%
5%
5%
9
5%
0
9
8
0%
7
7.
8
2
6
6.
95%
5
5.
100%
4
4.
7
1
3
3.
6
2
2.
1
2
3
4
5
6
7
8
9
0
1
1.
4
3
0
Which of the following organisms
are consumers?
9.
10.
89%
83%
8
2 2
5
5
9
6%
4
0
9
0%
8
8.
7
94%
7
7.
94%
89%
6
6.
94%
89%
5
5.
94%
4
4.
7
1 1
3
3.
6 6
2
2.
1
2
3
4
5
6
7
8
9
0
1
1.
3 3
4
0 0
Which of these are primary
consumers?
11%
56%
0%
78%
11%
22%
11%
44%
83%
0%
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
1
2
3
4
5
6
7
8
9
0
6
7
1
8
2
5
9
4
3
0