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Day 3: Energy Flow Through an

Ecosystem

Food Chains, Food Webs, Energy Pyramids

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Organisms that make their own energy through photosynthesis are calledProducers or Autotrophs.

Photosynthesis – process using light, CO2 & H2O to form energy (glucose)

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Organisms that cannot make their own energy & take energy from other sources are called Consumers or Heterotrophs

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•Carnivore– meat only •Herbivore– plants only•Omnivore– both meat & plants•Decomposer– breaks down & absorbs dead/decaying organisms; recycles material back into earth•Detritivore (scavenger)- eats dead organisms (carcasses)

Types of heterotrophs:

Examine the picture:

Who is the carnivore? ____________

Who is an herbivore? _____________

Who is missing from the food chain? _____

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Snake (2nd) , Hawk (3rd)

Mouse (primary, 1st)

Decomposers

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FOOD CHAIN:The transfer of energyfrom the sun to producers,to primary consumer, then to higher order consumer

The arrow represents the direction of energy flow.

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Each picture represents a TROPHIC LEVEL (energy level). The 1st trophic

level is always the PRODUCER.

Trophic Levels:Each step in the transfer of energy and matter

within a food chain.

1st Trophic Level:

Producer = Autotroph

2nd Trophic Level:

1st level consumer

3rd Trophic Level:

2nd level consumer

What does represent?_____________________________

4thTrophic Level:

3rd level consumer

Direction of energy flow – “eaten by”

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Food Webs:

•Are interconnectedfood chains

•They show more realistic feeding relationships in an ecosystem•Arrow represent the direction of energy flow.

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ENERGY PYRAMID:

-Can show the amount of energy flowing through an ecosystem. (it’s just a vertical food chain!!)

-The base of the ecological pyramid represents the autotrophs, or first trophic level. -Higher trophic levels are layered on top of one another.

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Movement up the levels will show a DECREASE in ENERGY

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100 %

10 %

1%90 % Loss

as Heat

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-Pyramid illustrates

that the amount of

available energy

decreases at each

succeeding trophic

level.

-only about 10% of the

food energy is

transferred

8000 joules

800 joules

80 joules

8 joules

How much energy would the

4th consumer get? 0.8

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10% of the energy is transferred. 90% is lost as HEAT as you move up the energy

pyramid.

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10% Rule

-Biomass is the total amount of living tissue at each trophic level

-As you move up the pyramid the BIOMASS(population sizes) DECREASES.

Pyramid of Biomass

-Pyramid of numbersis a model that shows the number of individual organismsat each trophic level

-As you move up the pyramid, the numbers of organisms (population size) DECREASES.

Pyramid of Numbers

Biological Magnification

Biological Magnification: when the concentration of a harmful substanceincreases in organisms at higher trophic levels in a food chain or food web

Ex. DDT was used to control pests. The pesticide moved up the food chain and birds would accumulate toxic levels of DDT which would cause their eggs to become fragile & break. The eagle almost became extinct, but lawmakers banned DDT and the eagle is now in recovery.

Ppm= parts per million