Trophic Levels, Energy

transfer and Pyramids

Vocabulary Trophic Levels – is the position an

organism occupies in a food chain. It refers to food or feeding.

Apex predator – top level predators with few or no predators of their own.

Food Chain

Food ChainsThe energy flow from one trophic level to

the other is know as a food chainProducers are at the first TROPHIC LEVELPrimary Consumers are the SECOND

TROPHIC LEVELSecondary consumers are at the THIRD

TROPHIC LEVEL

Trophic Levels (feeding levels)

3

2

1

Food Web

Most organisms eat more than JUST one organism

When more organisms are involved it is know as a FOOD WEB

Food webs are more complex and involve lots of organisms

Food WebsFood webs show ALTERNATIVE PATHWAYS other possible pathways through which an organism can obtain energy

Food webs

Trophic Level Producer, primary consumer, secondary consumer, tertiary consumer?

Grass

Mouse

Grasshopper

Frog

Owl

Hawk

Trophic Level Producer, primary consumer, secondary consumer, tertiary consumer

Grass 1st Producer

Mouse 2nd Primary consumer

Grasshopper 2nd Primary consumer

Frog 3rd Secondary consumer

Owl 3rd and 4th Secondary and tertiary consumer

Hawk 3rd Secondary consumer

Transfer of EnergyWhen a lion eats a zebra, it does

not get all of the energy from the zebra.

Energy lost is usually in form of heat

Energy lost from chain “link” to “link” is significant!

from grass to sheep, loss is about 90%!

10% Original Energy! 1% Original

Energy!

100% Energy Available

HEAT90%

HEAT90%

Energy lost from one trophic level (energy level) to the next level can be represented by a pyramid

PRODUCERS

1 CONSUMERS

2 CONSUMERS

3 CONSUMERS

4⁰ CONSUMERS

Each level above only gets 10% of the energy from below

Ex: 10,000 J of producers (plants) only give 10% of energy to primary consumers 1,000 J to primary consumers (snails,

minnows, dragonflies) 100 J to secondary consumers (small

fish) 10 J to tertiary consumers (big fish) 1 J to quaternary consumers (fish hawk)

ENERGY PYRAMID

10,000 J10,000 J

1,000 J1,000 J

100 J100 J

10 J10 J

1 J1 J

Energy Pyramid

Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)

Usually no more than 5 trophic levels since 6th level would have very little energy to keep it alive

Ecological Pyramid

• Which level has the most energy?• Which level has the most organisms?• Which level has the least organisms?• Which level has the least energy?

Pyramid of Numbers• Shows the numbers of individual organisms at each

trophic level in an ecosystem.

tertiaryconsumers

secondaryconsumers

primaryconsumers

producers

5

5000

500,000

5,000,0005,000,000producers

• A vast number of producers are required to support even a few top level consumers.

Biomass pyramid • Biomass is a measure of the total dry mass of organisms in a

given area.

tertiaryconsumers

secondaryconsumers

primaryconsumers

producers

75 g/m2

150g/m2

675g/m2

2000g/m2producers 2000g/m2