This document discusses energy flow through ecosystems and ecological pyramids. It defines trophic levels and explains that only about 10% of energy is transferred from one trophic level to the next, resulting in less available energy at higher levels. This 10% rule limits food chains to around 5 trophic levels. Ecological pyramids illustrate how biomass and energy decrease with each increasing trophic level as energy is lost through transfers between levels.

1. Energy Flow
Pyramid of Energy
Pyramid of Biomass

2. Definition of terms
Trophic Level- includes a group of
organisms that obtain food in a similar
manner

3. Producers
primary consumers
secondary consumers
Tertiary consumers
Quaternary consumers
Decomposers

4. Laws of Thermodynamics
Energy can neither be created nor
destroyed but can be transformed into
different forms.
When energy is transformed from one
form to another, there is always some
loss of energy from the system usually
as low grade heat.

5. 10% Law of Energy
Transfer(Lindemann 1942)
during the transfer of energy from
organic food from one trophic level to
the next, only about ten percent of the
of energy from organic matter is stored
as flesh. The remaining is lost during
transfer, broken down in respiration, or
lost to incomplete digestion by higher
trophic levels.

6. Only 10% of energy at a particular
trophic level is incorporated to the next
trophic level.
Rapid loss of energy explains why
food chain rarely has 5 links.

7. Principles of Energy flow
1. Ecosystems are dependent upon the
solar energy flow and finite pool of
nutrients
2. The primary source of energy for the
ecosystem is the sunlight.
3. All Energy content of organic matter is
eventually lost to the environment as
heat.

8. Producer
Primary consumer
Secondary consumer
Tertiary consumer
Quaternary consumer
Decomposer
heat
heat
heat
heat
heat
heat

9. Ecological Pyramids
Pyramid of Energy
Pyramid of Biomass

10. Pyramid of Energy- shows that as you go
higher the trophic levels, the amount of
energy decreases

11. Pyramid of Energy
Tertiary
Consumer
Secondary
consumer
Primary consumer
Producer

12. Energy of a trophic
level
utilized
Producing food
Growth and
development
including
regeneration
Not utilized about
10% for animals
and 20% for plants
Stored as flesh
(becomes part of
the biomass)
Available for the
next trophic level

13. Pyramid of Biomass
Biomass- quantitative estimate to the total
mass of living material
- amount of given energy at a
given time
-standing crop
Measuring biomass: total volume, dry
weight or live weight

14. Pyramid of Biomass- also shows that the
biomass decreases with each level of
food chain

15. Secondary
Consumer- 2
snakes (40 grams
Primary Consumer- 30
mice (500 grams)
Producer- 100 m² of grasses (10,000
grams)

16. Biomass of
a trophic
level
Not
consumed
consumed
Digested
Body
building
growth
Gained by
the next
trophic level
Released
as:
Heat
Inorganic
nutrients
Undigested
Undigested
fecal waste
Trophic
detritus

17. • Only uses samples from populations, so
difficult to measure biomass exactly.
• Time of year that biomass is measured
affects the result.

18. • Organisms of the same size do not
necessarily have the same energy
content.
• Inverted pyramids may result from
producers with high turnover rate.