2. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Overview
This slide set can be used for revision purposes. In this slide
presentation, you will explore feeding inter-relationships in
ecosystems.
This slide set relates to the following Integrated Science lesson:
You can access the subtopics in the Menu at the top of the slides.
2
Module 1: Unit 2: Lesson 7
Interactions in an ecosystem
3. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Objectives
When you complete this slide set you will be able to:
discuss feeding inter-relationships within an ecosystem.
construct a simple food-energy chain.
use food-energy chains to build a food-energy web.
demonstrate an awareness of the importance of plants in making
food and energy available to all animals.
show an understanding that the removal of any population from
an ecosystem can adversely affect other feeding inter-relationships
within that ecosystem.
describe a typical ecological pyramid used to show feeding
relationships.
show understanding that there are other types of interactions
within an ecosystem.
3
4. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Introduction
Have you ever thought about how you get food and where it actually
comes from??
4
http://schools.bcsd.com/fremont/4th_Sci_Life_food_chains.htm
No! … We’re not talking now about going
to the super-market or to the market to
buy ‘stuff’. What is the real source of our
food? Is it the same for animals like these?
Well …Let’s find out!
5. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feeding inter-relationships in an ecosystem
The interactions of the biotic components are an important
feature of an ecosystem.
Plants and animals interact with certain abiotic factors in the
ecosystem – e.g. gases, water, and also with each other,
especially for feeding -- e.g. as producer, consumer,
decomposer, and which under normal circumstances result in
balance in the ecosystem.
Some other examples of feeding interactions are: parasitism,
commensalism, symbiosis and predator-prey relationships.
5
7. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feeding inter-relationships in an ecosystem
From previous lessons you learnt the important role of plants in the
ecosystem. State the role of plants when considering the feeding
relationships in an ecosystem. Write your response in the box below
in one -two paragraphs. You must be in Slide Show view to
type/delete text in the box.
7
Plants are important because they
are the only living organisms that can
convert the sun’s energy, in the
process of photosynthesis, to a form
that is accessible and usable by
themselves and animals.
8. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feeding inter-relationships in an ecosystem
8
Carbon dioxide from the air
Energy from
Sunlight (or light)
Water and
minerals ions/alts
absorbed from
the soil
Food – some used
by plant; some
stored
JUST IN CASE YOU FORGOT!
Oxygen formed in
photosynthesis --
some given off and
some used during
respiration to
release energy
stored in food
9. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy chains
What are your feeding inter-relationships with other biotic elements
around you? We-ll…here’s that curried goat meal you ate yesterday…
Right?.
M-m-mm… delicious meat!!
9
Image source - midtownlunch.com
But where did the curried meat come from??
? ?
http://www.fotosearch.com/FSD297/x28117423/
10. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Aa-a-h-h Yes …… the goat!
Food-energy chains
10
Wonder what it got to eat
to make it grow so healthy
and its meat so tasty?
Of course! That goat’s been eating
mangoes! It got both food and energy.
11. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
So… let’s see now! Energy from sunlight was converted in the mango leaves
and stored in mangoes as chemical energy. The goat ate mangoes, and got
both food and energy. Then people ate goat flesh in which is food/energy.
Food-energy chains
11
When we show such a feeding relationship, we call that a
food-energy chain!
Why do you think it has that name?
Tell your teacher what you think.
Need help? Look at another example on the next slide.
MORE
12. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy chains
12
Image of cow - http://home-su-cool.blogspot.com/2011/01/c-cow-unit-plan.html
When one organism eats another as food, it
gets the nutrients and energy. So, in a food-
energy chain both food and energy are
passed along from one organism to another.
Why do you think the feeding relationship is called a food-energy chain?
Write your response in the box below. Click the CHECK button for feedback.
13. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy chains
Feedback continued:
Did you also consider these points ?
The word ‘chain’ in the name ‘food-energy chain’ indicates
that each organism is linked to others (for food) just the
same way the links of a real chain are joined to each other.
Also, the arrows show who eats what! They point to the
organism into which food and energy is going during the process of nutrition .
But it is not merely food (e.g., stored in the grass leaves) that is transferred!
Involved, also, is the passing of energy e.g. from the sun into green plants where
it is converted to chemical energy when the plants carry out photosynthesis. Then
energy is transferred into animals in the form of stored chemical energy in foods
eaten, so they can each carry out their various activities.
BOTH food and energy are involved in the feeding of one organism on another.
So, we correctly speak of a ‘food-energy chain!’.
14. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy chains
The food-energy chain always starts with producers, e.g.
green plants and algae.
14
Producers are autotrophs.
Do you remember what autotrophs are?
Type your response in the box below.
Click the CHECK button for feedback.
Autotroph comes from two words;
auto = self and trophe = nourishing.
So, an autotroph is an organism which
makes its own food to nourish itself.
Examples are all green plants and algae.
Photo: Langes0812.wordpress.com
15. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological Niches
a) Animals that are the first to take the food-energy from the
plants/producers are called primary consumers.
b) Animals that eat primary consumers are secondary consumers.
15
(a) Aphids feeding on leaf (b) Ladybug eating Aphids
16. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological Niches
Take note!
16
The word ending -vore comes from the Latin word which means
‘to eat’ or ‘to devour’.
Primary consumers are always herbivores - i.e. plant-eaters.
All consumer animals are heterotrophs who cannot make their own food,
but must rely on producers or other consumers to get food containing stored
energy. Click and read >
http://www.enchantedlearning.com/subjects/foodchain/glossary.shtml
http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/food_chains/revision/5/
Tertiary consumers can be omnivores that eat both plants and animals.
Secondary consumers are carnivores that eat only other animals – i.e.
flesh/meat-eaters.
17. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological Niches
Look at these examples of foods that humans eat. What kind of
consumer “vores” are we? Herbivores? Carnivores? No!!
Humans are omnivores! We eat plants & animals.
17
From this wide range
of foods that we eat,
would we be
confined to only one
food-energy chain?
http://www.jamaicanfoodsavvy.com/
http://en.wikipedia.org/wiki/Ackee_and_saltfish
terriblefunny.blogspot.com
18. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological Niches
In real life, feeding relationships are quite complicated!
This bird is the Jamaican Tody. It is an omnivore, as it feeds on
insects/larvae and on fruit.
What are two food-energy chain/s
that show those inter-relationships?
fruit tree insect bird (Tody)
http://www.nepa.gov.jm/projects/project_reports/3rd_national_security_summary.pdf
19. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy webs
An animal can be involved in several different
food-energy chains at the same time!
We show this with a food-energy web.
A web has several food-energy chains criss-crossing
each other and shows the various food-energy inter-
relationships possible/likely in a community of different
populations of plants and animals.
19
20. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy webs
How many different
food-energy chains
do you see connected
to the mango tree?
Where in that web could a lizard be placed?
mango tree ants lizard small bird
Seven
21. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy webs - In an aquatic ecosystem
21
Look at an example of feeding inter-relationships in an aquatic
ecosystem. Examine and discuss within your group the various food-
energy chains that comprise this web.
http://bookbuilder
.cast.org/view_prin
t.php?book=7077
22. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Food-energy webs – In an aquatic ecosystem
From the previous diagram, give an example of:
22
1. Diatoms are fed on by krill
and small water animals.
2. Fish are fed on by seals,
whales and penguins.
3. Whales feed on fish, tiny
water animals, penguins and
seals.
1. ‘One organism can be fed on
by more than one organism.’
2. ‘More than one organism may
feed on the same animal.
3. ‘Many organisms feed on more
than one type of food.’
23. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Constructing food-energy webs
Have Fun with food webs; do the activities at >
http://www.harcourtschool.com/activity/food/food_menu.html
Work with a partner to construct food webs from this site>
http://www.vtaide.com/png/foodweb.htm
Now, test your understanding of food-energy chains/webs. Click to
this website and follow the instructions there.
http://www.harcourtschool.com/activity/food/food_menu.html
Click open this website and learn the niches of various organisms by
fixing different food chains/webs.
http://www.gould.edu.au/foodwebs/kids_web.htm
23
24. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
24
Here’s a food-energy
web that shows an
example of feeding
inter-relationships
among different
populations of plants
and animals in a
marshland ecosystem.
Image - http://waynesword.palomar.edu/lmexer10.htm#foodweb
25. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy chains
It is said that “a chain is only as strong as its weakest
link”. In an ecosystem, the chain signifies that there exists
strong links or inter-relationships between the plants
(producers) and animals (consumers), such that if one
“link” were to weaken, disappear/ be missing, it would
adversely affect the others, just the same way as if one
link in a real chain were to become weakened, break/lost.
Go through the next slides for a possible scenario of what could
happen in that marshland.
Discuss it among group members and arrive at consensus at each
stage!
25
26. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
26
THINK AND TELL
What do you predict
would happen if
disease, pesticides or
over-hunting were to
kill off the entire (or
the majority of the)
population of hawks
living there?
Click here for possible
answer!
27. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
27
There would be no
hawks to eat the
snakes, so the
numbers in the
snake population will
increase.
cont’d
28. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
28
As the snake
population
increases, the
entire frog
population will
decrease and
soon disappear as
they get eaten by
the increased
amount of snakes.
29. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
29
Now… No frogs
to eat the
crickets and they
have a lot of
cattail plants!
What will
happen to
crickets and
cattails?
Yes..cricket
population
increases …
cont’d
30. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
30
Most of the
cattail gets
eaten by the
increase in the
population of
crickets.
cont’d
31. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
31
Eventually the
crickets don’t
have enough
food, so their
numbers
decrease!!
And so on …
and so on……
32. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Disrupting food-energy webs
“When an organism dies, the size of the population
changes. Changing the size/numbers of one population in
a food-energy chain affects other populations. This is
because populations within a food chain depend on other
populations (for food!) to help them survive.” Without
adequate amount of food for all members of a population,
there is starvation and death!
http://sites.education.miami.edu/psell/files/2011/10/Energy-in-
Ecosystems.pdf
32
33. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological Pyramids - Pyramid of Numbers and
Pyramid of Energy
33
In an ecosystem, it
takes a lot of
herbivores to
eventually provide
food and energy for
one lop level
consumer.
Click and watch >
http://www.harcourtsch
ool.com/activity/science
_up_close/314/deploy/in
terface.html
34. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological pyramids
“ The pyramid of numbers and energy pyramid would have
many (green plants) providing food and energy to …(grasshoppers).
…As we go up, there .. (would be) fewer (grasshoppers) than (frogs),
(fewer snakes than frogs) and (at the highest trophic/feeding level,
even fewer (hawks) than… (snakes). So ... as we go further along a
food chain, there are fewer and fewer consumers. In other words, a
large mass of living things (e,g, producer plants) at the base is
required to support a few (consumer animals) at the (next trophic
level, and... many herbivores are needed to support a few
carnivores.” Ref.: Modified from>
http://www.vtaide.com/png/foodchains.htm#create
34
35. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Ecological pyramids - Availability of energy
As energy passes to a higher trophic level, approximately 90% of
the useful energy is “lost” or “wasted” as heat. High trophic levels
contain less energy and fewer organisms than lower levels.
At each trophic level in a food chain, energy is used by the
organisms at that level to maintain their own life process. As we
know from the Law of Energy Conservation, not all energy
transfers and conversions result in 100% “useful”. Some energy is
“lost’ or “wasted” to the surroundings as heat. It is estimated that
in going from one trophic level to the next, about 90 % of the
energy is dissipated.
In moving to the next trophic level, only 10 % of the original
energy is available. By the third trophic level only 1% of the
energy is available.
35
36. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Balance is important!
Ecosystems will fail if their biotic and abiotic components do
not remain in balance.
The carrying capacity of each ecosystem to accommodate
populations of organisms depends on its continued ability to
keep in balance the interactions of the biotic components with
the ecosystem for: food, water, shelter and other important
abiotic factors.
No community can carry more populations
of organisms than its abiotic factors can
accommodate.
36
37. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Summary
You should now appreciate how the biotic components affect
each other either directly or indirectly within an ecosystem!
Because plants are the source of food and for passing
energy to all organisms, it is likely that one kind of plant can
be food for more than one kind of animal.
Many kinds of animals may feed on the same kind of animal
or plant.
One kind of animal may feed on more than one type of
organism.
So, there are complex interactions and inter-relationships
associated with nurition!
37
38. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Quiz and Review Questions
Are you ready to test yourself?
1. There are three Multiple Choice (MC) items and three short
Review Questions that you are required to do,
2. For each MC item, click on the letter of the correct response
3. Click the FEEDBACK button and read the feedback provided.
4. Click the button ‘NEXT QUESTION’ to continue.
5. Click the button BEGIN QUIZ to start doing the quiz.
38
BEGIN QUIZ!
39. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
QUIZ: Question 1
The sequence of energy flow through a food chain is
39
A. producer secondary consumer primary consumer.
D. higher order consumer primary consumer producer.
B. primary consumer producer higher order consumer.
C. producer primary consumer secondary consumer.
FEEDBACK
40. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feedback to Question 1
The sequence of energy flow through a food chain is
40
NEXT QUESTION
Energy flow always starts from the producer.
Although option A starts with a producer, energy cannot flow
from of secondary consumer back to a primary consumer.
The correct option is ‘C’.
41. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Quiz: Question 2
Which of these food chains is in the correct order?
41
A. grasshopper grass frog snake
D. grass frog grasshopper snake
C. snake frog grasshopper grass
B. grass grasshopper frog snake
FEEDBACK
42. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feedback to Question 2
Which of these food chains is in the correct order?
42
NEXT QUESTION
Again, the food chain starts with a producer so options A and C
are not possible.
Option D starts with a producer but the primary consumer
(grasshopper) is in the wrong place.
Primary consumers can only eat producers. The correct option is
therefore ‘B’.
43. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
QUIZ: Question 3
A caterpillar eats a leaf, and a bird eats the caterpillar. In this
interaction, the bird is a:
43
B. primary consumer
D. producer
C. herbivore
A. secondary consumer
FEEDBACK
44. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feedback to Question 3
A caterpillar eats a leaf, and a bird eats the caterpillar. In this
interaction, the bird is a …
44
This is what the food chain would look like.
Leaf caterpillar bird
That would make the leaf a producer, the caterpillar a
primary consumer (herbivore), and the bird a secondary
consumer.
The correct option is therefore ‘A’.
END OF QUIZ
45. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Review Question 1
45
Food Chain 2: sun’s energy mango → rat → hawk
(1) Write the food-energy chain shown in this diagram, and (2) show a
second one, based on this diagram and with no additional organism included.
Food Chain 1: sun’s energy mango → rat → owl → hawkFOOD CHAIN 1
FOOD CHAIN 2
46. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feedback to Review Question 2
What feeding niche does each organism occupy in #(1)
food-energy chain?
The mango tree = a producer;
the rat is the first animal to get both food and energy from the
plant producer, so, in this food-energy chain, it is a primary
consumer and is actually feeding as a herbivore (NOTE: Rats are
actually omnivores!).
The owl is a secondary consumer, and, by eating animal
flesh/meat, also a carnivore .
The hawk is a tertiary consumer and a carnivore too.
46
Click here for feedback to Review Question 2
47. Objectives
Feeding inter-
relationships in
an ecosystem
Food energy
chains
Ecological
Niches
QuizIntroduction
Food energy
webs
Ecological
Pyramids
Feedback to Review Question 3
In the previous diagram, which animal is both a predator
and a prey? Explain.
Depending on its position in a food-energy chain, an animal can be
both a predator and prey. In food-energy chain # (1), the owl is a
predator on the rat, but can become a prey to the larger hawk. In
#2, the owl is the predator
NOTE: Each consumer in a food-energy chain can be either predator
or prey depending on the tropic levels in each chain!
47
Click here for feedback to Review Question 3