Ecological PyramidsEcological PyramidsChapter 2 Section 2b

Learning TargetsLearning Targets1. I can model the use of

ecological pyramids

Ecological PyramidsEcological Pyramids• Another model that shows how

energy flows through ecosystems is the Ecological Pyramid• Ecological Pyramids are models used

to represent trophic levels in ecosystems

• There are 3 different ecological pyramids:•Pyramid of Energy•Pyramid of Biomass•Pyramid of Numbers

Pyramid of EnergyPyramid of Energy• In an ecosystem, only 10% of

the energy from each organism in a food chain is actually passed on when consumed for food• 90% of the energy is lost through

cell processes and as heat• Pyramids of Energy model this

effect on an ecosystem

Pyramid of EnergyPyramid of Energy• In a Pyramid of

Energy, each level represents the amount of energy that is available to that trophic level.• With each step up

the pyramid, energy decreases

Pyramid of BiomassPyramid of Biomass• Ecologist also study how biomass

is effect at each trophic level using a Pyramid of Biomass• Biomass – the total mass of living

matter at each trophic level• As you move up the pyramid, there

is less biomass because there is less energy available at that trophic level

Pyramid of BiomassPyramid of Biomass

10kgOwls

50kg Snakes

100kg Mice

900kg Grasses

Tertiary Consumer

Secondary Consumer

Primary Consumer

Producer

Pyramid of NumbersPyramid of Numbers• The last type of pyramid is the

Pyramid of Numbers, which represents the number of organisms present at each trophic level• The relative number of organisms

at each trophic level decreases because there is less energy available to support the organisms

Ecological PyramidsEcological Pyramids

TertiaryConsumers

90,000 SecondaryConsumers

200,000 Primary Consumers

1,500,000Primary Producers