Warm-up

1
Warm-up

• Use complete sentences to describe how the number
  of species in lower trophic levels compares with
  the number of species in higher trophic levels.
  Explain a reason for why this occurs.

2
What causes the numbers of individuals in a
population to decrease from producer to top level
consumers?
3
Number of organisms in a trophic level compared
with total energy in a trophic level

• Think about how many individual insects could be
  supported by one individual tree
• We usually compare trophic levels by how much
  total energy the trophic level contains rather
  than the total number of organisms in a trophic
  level

4
Pyramid of energy example
5
10 Rule in Ecology

• An average of only 10 of the energy in one
  trophic level is passed to the next trophic
  level.

6
10 rule...
7
10 rule diagrams...
8
10 rule diagrams...
9
How much energy is at each level?
10
How much energy is at each level?
9 Cal as heat
90 Cal as heat
900 Cal as heat
11
10 Rule

• Why do you think only 10 of the total energy
  from 1 trophic level is passed to the next?

12
3 Reasons for decrease in available energy

1. Energy is used up for daily life activities.
2. Not all organisms that die are eaten by animals
   in the next trophic level.
3. Not all parts of an organism are eaten and
   digested for energy.