Pyramids OfEnergy

D. Crowley, 2008

Pyramids Of Energy

Friday, April 21, 2023

Big Mac

Where does the energy in a Big Mac come from?

It comes from the cows that make the

burger

It comes from the sugar in the

burger sauce

There is no energy in a big

Mac – that is why they are bad for

you

It comes from the sun

It comes from the green parts

because they are healthier

Big Mac

All the energy within our food originates from the sun – transferred through food chains...

It comes from the sun

Review: Food Chains and Webs

Food chains show a single flow of energy through a ecosystem.

These are simplified: nature is much more complicated!

Producer Primary Consumer Secondary Consumer Tertiary Consumer

Review: Food Chains and Webs

A Food Web gives a better idea of how energy flowsBut it is very messy and

hard to read!

There is a better way to visualize the flow of energy through a system

Pyramid Of EnergyWe organize food webs into trophic levels of an energy pyramid

Energy flows up the pyramid!

Each level is determined by where (who) an organism gets its energy from.

In other words…who do they eat?

These are called “trophic” levels. Trophic = “feeding.”

Pyramid Of Energy

The lowest level is getting their energy from the sun. In other words, they make their own food

Called “autotrophs.”Auto = “Self”

Label the correct level on the pyramid.

Which organism is an autotroph?The Oak Tree

Pyramid Of EnergyThe next level gets their energy from the producer.

Called “heterotrophs.”Hetero = other

Since all the levels above producer eat others, we call them all “Heterotrophs.” Label the correct sections of the pyramid Which organisms are heterotrophs? Sparrow hawk, Bluetit and caterpillar!

Pyramid Of Energy

The last type of organism gets their energy from things that have died. We call the organisms that get their energy from

other dead organisms…Decomposers!

Listed outside the pyramidDraw a decomposer on the pyramid

Pyramid Of Energy

Pyramid Of Energy

Why is each level smaller than the level below it?Not all of the energy that was taken in by the lower

level is available to the level above. It is lost as:

1. Heat (into space).2. Waste (poop)

Approximately 90% is lost at each level.

Pyramid Of Energy

How much is available to level above? 10% This is called the 10% Rule

Units: Measured in kCal (kilocalories) or KJ (kilojoules)

Pyramid Of EnergyUnits: Joules or Calories

Autotroph: 123,000 KJ

1st Order Heterotroph:12,300 KJ

2nd Order Heterotroph :

1,230 KJ

3rd Order Heterotroph:

123 KJ

Pyramid Of EnergyLabel the trophic levels and add the values to each level:Trophic Level 3rd order

Heterotroph 53kCal

2nd order

Heterotroph 530kCal

1st order

Heterotroph 5300kCal

Autotroph 53000kCal

Where does the rest go??

90% of each level, lost as

heat

Pyramid of Numbers

The population of each organism in a food chain can be shown in a sort of bar chart called a pyramid of numbers The more organisms there are, the wider the bar. The producer in the food chain always goes at the bottom of

the pyramid of numbers

E.g. clover snail thrush hawk

Pyramid Of Number

Pyramids of number show how many organisms there are in a habitat

What might a pyramid of number for the food chain below might look like ? -

If there were 200 grass plants; 25 voles; and 1 barn owl

Pyramid Of Number

Pyramids of number show how many organisms there are in a habitat

However they may not always look like classical pyramids: -

Here there are much more caterpillars than there are oak trees which is why the pyramid is oddly shaped.

Pyramid Of BiomassBiomass means the amount of biological

material.

It is measured as total dry mass of organisms in a given area (all the water is taken out… dehydrated).

Pyramid Of BiomassThe pyramid shows the amount of biological

material at each trophic level.

This means the oak tree has the most biological material while the sparrowhawk has the least.

Units: g/m2, lbs/m2, kg/m2

Pyramid Of BiomassThe conversion of biomass from one

trophic level to the next is inefficient-From producer to primary consumer.From primary consumer to secondary

consumerFrom secondary consumer

to tertiary consumer, etc.

Pyramid Of BiomassWhy? Energy is lost as heat.Matter (biomass) is lost as waste.