Predator- Prey Relationships
A relationship in which one organism
kills another for food is called a
predator-prey relationship.
• The organism that does the hunting is
the predator.
• The organism that is hunted is the prey.
Food chain vs. Food Web
The path of energy that shows feeding
relationships between organisms is called
a food chain. Since most animals feed at
several levels, their paths interconnect,
forming a food web.
Roles in the Ecosystem
An organism’s role in the
environment is called its
niche.
Producers (Autotrophs):
capture energy from the
sun, convert to organic
material – plants. Ex.
Plants, Bacteria, Algae
Consumers
(Heterotrophs):
organisms that gain their
energy from eating other
organisms. Cannot
make their own food!
Trophic Levels
Trophic levels are the feeding position in a
food chain. Green plants, which are
producers, form the first trophic level.
Consumers form the second trophic level
(herbivores), while carnivores and omnivores
form the third and even the fourth trophic
levels. Detritovores eat all dead things.
4 types of Consumers
• 1. Carnivore
• Eat only meat
• 2. Herbivore
• Eat only plants
• 3. Omnivore
• Eat both plants and animals
• 4. Decomposer
• Breaks down organic matter
Think, Pair, Share
•
What category would the following
organisms be classified under?
• Producer or Consumer
• Carnivore, Herbivore, Omnivore,
Detritivore, Decomposer
1. Human
2. Horse
3. Mouse
4. Shark
5. Fungus
ARROWS
• Arrows are used in a food chain to show THE
DIRECTION IN WHICH ENERGY IS MOVING!
Food Webs
• A series of interconnected food chains
Energy Transfer
Energy Transfer - as
you go up trophic
levels, organisms
lose energy.
An ecosystem can
support more
primary consumers,
than tertiary
consumers.
Generally, only 10% of the energy is available to transfer
to organisms in the next trophic level. Most of it is lost as
heat.
Trophic Levels
• Each step in a
food chain/web.
• What trophic level
is the mouse on?
• Which two
organisms are
producers?
Trophic Levels
• Energy is always lost as it moves from one
trophic level to the next.
• Why would energy be lost as it moves
from producerconsumer?
• Energy is lost through heat during the
chemical reactions that break food down
• Only 10% of
energy is
available for
organisms of
the next
trophic level.
This is also why there
are more organisms
on the lower levels
of the energy
pyramid and only
one or two top
consumers. There is
more energy
available at those
levels.
•Where is the greatest amount of energy concentrated
in this pyramid?
•Who gets the least amount of energy from the
perennial grass?
Where do detritivores fit in?
• Because they eat dead organisms, they fit
in at the top of the energy pyramid/food
web.
Energy pyramids
•If the first trophic level started off with 599,000Kcal,
how much energy will go to EACH level above it?