Ecological Pyramids:

graphs which illustrate the trophic levels in a community.

Most ecological pyramids are large at the base and narrow at

the top.

This is because every time that an organism is eaten by the next trophic level, some of the energy is lost as

heat. More Energy

Less Energy

3 TYPES OF PYRAMIDS:

1. Pyramid of Biomass2. Pyramid of Energy3. Pyramid of Numbers

Pyramid of Biomass:• Illustrates the amount of biomass in each trophic level

– Biomass weight is determined after dehydration

• Shows the amount of matter lost between trophic levels.

• Measured in Kg, grams or pounds

Pyramid of Biomass P

yram

id o

f Bio

mas

s

Pyramid of Energy:• Shows the energy available at each trophic level.

– The size of the blocks represents the proportion of productivity– Measured in Joules or Calories

Pyramid of Energy:• Most of the energy available to the community

is in the 1st trophic level.• Only 10-20% of the energy is available to the

next trophic level (≈ 90% lost)

Pyramid of Numbers:• Illustration of the number of organisms at

each level

What kind of Pyramid

is this?

Energy, the trophic levels are measured in Kilocalories

How can more people be supported on Earth when there is a limited supply of resources?

Human Population Growth

It depends on what they are eating…

The End or is it just the beginning…