Transcript Unit 2 Food chains and webs 14-15

Feeding Relationships
Food Chains
Food Webs
Trophic Levels
10% Rule
Biomass
Food Chain
• Food chain- A series of steps in an ecosystem in
which organisms transfer energy by eating and by
being eaten.
The sun is the original energy source for producers, but consumers rely on
carbohydrates and lipids for energy from the food they eat.
Food Webs
Are a network of
complex of
feeding
relationships.
A food web links all
the food chains in an
ecosystem together.
Trophic Levels
A trophic level is a step in a food chain or web is called a
trophic level
Producers(1st level)
plants, trees, grass, algae
Consumers (2nd – 4th level)
Primary
grasshopper
Secondary
frog
Tertiary
snake
Trophic Level
• Add new trophic levels diagram
Trophic Levels
Each consumer depends on the trophic level below for energy
Autotroph
Organism that is able to capture energy from sunlight or chemicals and make
their own food.
Ex. Plant and Algae
Heterotroph
Organism that obtains food by consuming other living things, also called a
consumer.
Ex. Lion and human
Food Web Analysis
Are there any primary
consumers that can also be a
secondary consumer?
What would happen to the
food web if –
A) The harvest mice
where to die off in the
area?
B) The algae died?
C) The grasshopper died?
Food Web
Food web
Explains all of the feeding relationships at each trophic
level in a community.
A food web is more realistic than a food chain since
most organisms feed on more that one organism.
Food Web Example
Cooper’s Hawk
Loggerhead Shrike
American Kestrel
Shrew
Grasshopper
Cricket
Deer Mouse
Grass & Seeds
Sparrow
Food Web Activity
10% Rule
As energy is transferred from one trophic level to the
next 90% of the energy is lost as heat to the
environment
Why do we call it the 10 % rule?
Only 10% of the available energy is transferred to the next
trophic level
• New 10 % rule diagram so students can model their own
10% Rule
• Have the students create a diagram
Ecological Pyramids
• Ecological pyramids – show the relationships in food chains and
food webs
• The bottom of the food pyramid represents the producers, the
next level the herbivores, the next the 1st carnivore, and the
next and/or top carnivore.
Carnivore
Herbivore
Producer
Ecological Pyramids
•Ecologists recognize three different
types of ecological pyramids:
•energy pyramids
•biomass pyramids
•pyramids of numbers
Energy Pyramid
• Energy Pyramid- Shows the relative amount of energy at each trophic
level.
Energy Pyramid
Biomass Pyramid
•Biomass- The total amount of
living organic matter at each
trophic level.
Biomass Pyramid
Pyramid of Numbers
• Pyramid of numbers- Shows the relative number of individual
organisms at each trophic level.
Pyramid of Numbers
What is Ecology?
 Ecology- The study of organisms and how they interact with their
environment. (includes both biotic and abiotic factors).
What is an Ecosystem?
 Ecosystem- A collection of the organisms that live in a particular
place together with their nonliving or physical environment.
Biotic & Abiotic Factors
 Biotic factors – the biological influences
on an organism within an ecosystem,
the living cast of living characters.
Biotic v. Abiotic Factors
 Abiotic factors – physical or non living factors
that influence an ecosystem.
Levels of Organization within an
Ecosystem

The study of ecology ranges from the study of individual organisms
to the study of the entire biosphere.
1.
2.
3.
4.
5.
6.
Species (Individual)
Population
Community
Ecosystem
Biome
Biosphere
Levels of Organization
1.
A species is a group of organisms that can breed and produce
fertile offspring. (ex: black bears)
2. A population is a group of individuals that belong to the same
species and live in the same area (ex: all the black bears in
Yellowstone Park)
Levels of Organization
3.
A community is a group of different populations that live
together in a defined area. Exp. lions and tigers and bears living
in the same area
4. A ecosystem is a collection of all the organisms that live in a
particular place, together with their physical environment
Levels of Organization
5. A biome is a group of ecosystems that have the same climate and
dominant communities.
6. A biosphere is the parts of the earth in which life exists, including
land, water, air and atmosphere.
Ecology: Levels of Organization
The Niche
 An organisms' niche is the full range of
physical and biological conditions in
which the organism lives and the way in
which it uses those conditions.
The Niche
A organisms niche includes
- the type of food it consumes
- how it obtains food
- physical conditions necessary to survive
- the organism's reproductive pattern
Niche v. Habitat
 An organisms habitat is where it
lives.
 An organisms niche is how it lives.
No two species can share the same
niche in the same habitat.
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches