Ecological Pyramids
Name:
Period:
Date:
Background: Ecological pyramids are diagrams that show the relative amount of
energy or matter within each trophic level in a food chain or web. There are three
types of ecological pyramids: an energy pyramid, a biomass pyramid, and a pyramid
of numbers.
Energy Pyramids
1%
Secondary
Consumers
10% Primary
Consumers
100% Producers
Energy pyramids show the relative amount of
energy that is available to each trophic level.
Only about 10% of the energy available in
one trophic level is transferred to organisms in
the next trophic level. The other 90% is lost
through heat and other body processes.
1. List 2 body processes in which you think
energy is lost.
a. ______________________________________
b. ______________________________________
Biomass Pyramids
Biomass is the total amount of living tissue
available within a trophic level. It
represents the amount of potential food
available within a trophic level.
2. What does the prefix “bio” mean?
What does “mass” mean?
________________________________________
________________________________________
Pyramid of Numbers
A pyramid of numbers shows the relative
number of individual organisms within
each trophic level. Unlike an energy or
biomass pyramid, a pyramid of numbers is
not always shaped like a typical pyramid.
For example a single tree can support a
large number of insects and birds.
3. Explain why the top of the pyramid
generally has the fewest organisms.
________________________________________
________________________________________
© Science Lessons That Rock
Energy Pyramid
4. Which organism is the producer?
______________________________________
5. Which organism is a secondary consumer?
______________________________________
6. Which organism is an herbivore?
______________________________________
7. How much energy per year do the
grasshoppers obtain from eating 1 square
meter of grass? _______________________
8. What percentage of the energy that
was originally absorbed by the grass is
4,000
kcal
passed on to the grasshoppers?
______________________________________
9. What percentage of the energy that
24,000
kcal
was originally absorbed by the
grasshoppers is passed on to the
bluebirds?
______________________________________
10. Explain why an energy pyramid in an
ecosystem is limited to only 4 or 5 levels.
______________________________________
______________________________________
______________________________________
______________________________________
35
kcal
420
kcal
Hawk
Bluebird
Grasshopper
Grass
Energy values are
per square meter
per year.
BIOMASS Pyramid
11. Which organism(s) is an carnivore?
______________________________________
12. Where does the algae initially receive
energy from? ________________________
13. If you were to examine the organisms living
in the river ecosystem, which organism
would you see the least often?
______________________________________
14. What type of organism is missing from this
pyramid? (Hint: Who returns nutrients to
the soil?) _____________________________
800
15. Explain why a vegetarian diet is
g/m2
considered a more energy efficient diet
for humans than one based on meat.
______________________________________
______________________________________
______________________________________
______________________________________
1.5
g/m2
12
g/m2
57
g/m2
Bass
Tadpole
Daphnia (water flea)
Algae
© Science Lessons That Rock
Pyramid of Numbers
DRAWING:
16. In the blank space to the right, sketch a
pyramid of numbers for the following food
chain:
Owl
1
Skunk
20
Mouse
800
Seeds
11,000
17. Is this pyramid of numbers shaped like a
typical pyramid? Explain.
______________________________________
______________________________________
______________________________________
______________________________________
18. If you were to draw an energy pyramid for
this same food chain, would it be shaped
like a typical pyramid? Explain.
______________________________________
______________________________________
______________________________________
______________________________________
19. In the blank space to the right, sketch a
pyramid of numbers for the following food
chain:
Snake
2
Toad
15
Caterpillar
1000
Oak Tree
1
DRAWING:
20. Is this pyramid of numbers shaped like a
typical pyramid? Explain.
______________________________________
______________________________________
______________________________________
______________________________________
21. If you were to draw a biomass pyramid for
this same food chain, would it be shaped
like a typical pyramid? Explain.
______________________________________
______________________________________
______________________________________
______________________________________
© Science Lessons That Rock