Yo!*
*Read the
entire board!
*Note change
to
homework!!!!

Please have
your
homework on
your desk for
a stamp 
Comparative Niches
 Share with your neighbor!
 Find the strongest comparison in the group.
 Statement: Even though ecosystems are different,
they need to have the same niches.

Agree or disagree? Defend your choice!
Energy flow in ecosystems
Energy Pyramid
 Graphic
representation of
energy available at
each
trophic level.
• ecological

efficiency
90%
is lost in
5%energy
to 20%
transfer between
trophic
• 10% levels:
efficiency
motion, body heat,
general rule
metabolism,
growth
 10% Rule: Only 10%
of energy is available
to next trophic level.
Fig. 4–16
© Brooks/Cole Publishing Company / ITP
Energy pyramids – key
understandings
 Explain why there are no more than 5 or 6 links in a
food chain.
 Give us our language “lower/higher” on the food
chain.
 Can NEVER be “upside” down
 Explain why top predators like wolves need lots of
land to find enough food to survive.
Fig. 4–17
© Brooks/Cole Publishing Company / ITP
Prairie Ecosystem
Hawks
Snakes
Mice
Grasses
Our food chain – which would provide more
total calories for 7 billion people?
human
human
animals
plants
plants
Biomass Pyramids measure
mass
Fig. 4–18
© Brooks/Cole Publishing Company / ITP
Pyramids of Numbers
Fig. 4–19
© Brooks/Cole Publishing Company / ITP
Net Primary Productivity
A measure of the rate at which autotrophs store biomass.
Net primary productivity = photosynthetic rate of plants –
respiration rate of plants.
Primary Productivity determines the shape of the pyramids’ base
(and then the next levels up)
Primary Productivity (per area)
Fig. 4–21
© Brooks/Cole Publishing Company / ITP
Check for understanding!
 Key understandings of energy pyramids
 Where does 90% of the energy go?
 How to calculate energy at each level (units?)
 Exceptions to numbers and biomass pyramids