1. PYRAMIDS
EQ: How is energy calculated through a food chain?

2. Ecological Pyramids Does this pyramid represent a food chain or web?
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
How could this pyramid be changed to represent a food web?
Ecological Pyramids
Does this pyramid represent a food chain or web?
A chain as there is only one eating path.
How could this pyramid be changed to represent a food web?
Different species of organisms could be added at each level to show more eating “opportunities for the organisms above it.
Broaden the discussion by asking “What organisms could you add at each trophic level for a web??

3. Pyramid of Energy 0.1% 1% 10% 100% Tertiary consumer Primary consumer
Producer
Primary consumer
Heat
100%
10% 1%
0.1%
Tertiary consumer
Ecological pyramids are models that show the relative amount of energy or matter contained within each trophic level in a given food chain or food web. There are three different types of ecological pyramids: pyramids of energy, pyramids of biomass, and pyramids of numbers.
Explain that only a small portion of the energy that enters any trophic level is available to organisms at the next level. This is because organisms expend much of the energy they acquire on life processes, such as respiration, movement, growth, and reproduction. Most of the remaining energy is released into the environment as heat.
Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web. On average, about 10 percent of the energy available within one trophic level is transferred to the next trophic level.

4. Pyramid of Energy
Grass (10,000 kcal)
Grasshopper (_____ kcal)
Frog (___ kcal)
Snake (___ kcal)
Hawk
(__ kcal) 1 2 3 4 5
The numbers in parenthesis represent the amount of energy present at each trophic level.
Ecological Pyramids
What do the big numbers represent?
The trophic levels. Have them identify the type of organism at each level.
What does the kcal mean?
It stands for kilocalories, a measurement of energy.

5. Pyramid of Energy
Only 10% of the energy is transferred to organisms at the next trophic level
Ecological Pyramids
What happens to the energy as you go up?
It gets less and less; lost in heat energy or used in metabolism.
What is the energy loss between levels?
The rule of thumb is 10% (although it is an average across levels and chains.) No trophic level can contain more energy than the level below.

6. Pyramid of Energy 1 kcal 10 kcal 100 kcal 1000 kcal Tertiary consumer
Producer
Primary consumer
Heat
1000 kcal
100 kcal
10 kcal
1 kcal
Tertiary consumer
Secondary consumer

7. Pyramid of Numbers
Illustrates the relative number of organisms at each trophic level.
Ecological Pyramids
What information would this pyramid include if it were a pyramid of numbers?
It would have the total population at each level or it would have a key for how organisms were represented by each picture.
How do they get a number total for a population of organisms?
The population is determined by counting the organisms of a species in a sample portion at each level and then calculating an average for the total area.

8. Pyramid of Biomass
Illustrates the total amount of living tissue at each trophic level.
Ecological Pyramids
What information would this pyramid include if it were a pyramid of biomass?
It would have the total biomass at each level or it would have a key for how much biomass was represented by each picture.
How do they get a number total for the biomass of a population?
The total mass of the organisms is determined by drying and weighing a sample number of organisms at each level and then calculating the total mass for the species at each level.

9. Ecological Pyramids What is different about this pyramid?
How can the producer level be so small and support the trophic levels above it?
Ecological Pyramids
What is different about this pyramid?
It has a very small trophic level 1 (producers)

11. Pyramids of Aquatic Ecosystems
Numbers
Biomass
Energy
Pyramids of Aquatic Ecosystems
Numbers - Follows the normal pattern of having many more phytoplankton at TL1
Biomass - The phytoplankton reproduce a a rate only just slightly higher than the rate at which they are eaten. Since they are so small and weigh so little there is a very small biomass.
Energy - Follows the normal pattern of having much more energy available at TL1
Pyramid of biomass in aquatic ecosystems (ocean & fresh) and some terrestrial ecosystems such as the pyramid of numbers for the temperate forest. Because the trees are so large their numbers are small compared to the number of organisms at the higher trophic levels.
Phytoplankton are microscopic and weigh very little

12. Pyramids of Temperate Forests
Numbers
Biomass
Energy
Trees are huge but not as numerous as many smaller forest creatures.
Pyramids of Aquatic Ecosystems
Numbers - In the temperate forest, the trees are huge but smaller in number compared to the grasses in a prairie and so are fewer compared to the number of organisms at the higher trophic levels.
Biomass - Follows the normal pattern of having much more mass at TL1 from the huge trees.
Energy - Follows the normal pattern of having much more energy available at TL1