Interpreting Food Webs

Energy Diagrams

Food Chain- shows a single pathway of energy flow in an ecosystem

Food web- shows multiple pathways of energy flow in an ecosystem

Energy pyramid shows how energy is lost as you move from one trophic level to the

next.

• Food Chain

• Food Web

• Energy Pyramid

Trophic Levels

Trophic levels refer to the position an organism occupies in a food chain.

First trophic Level

Second Trophic Level

Third Trophic Level

Fourth Trophic Level

Producers are always found in the first trophic level

Trophic Levels cont….

• Biomass- the amount of organic matter (nutrients) comprising a group of organisms in a habitat.

– As you move up a food chain, both available energy and biomass decrease.

– Energy is transferred upwards but is diminished with each transfer.

– Energy Pyramid - A diagram shaped like a triangle that shows the loss of energy at each level of the food chain.

Energy Pyramid

• Only energy stored in tissues of an organism can be transferred to the next level.

• The higher up in the pyramid an organism is, the more they must eat to obtain energy.

III. All Living Things Need Energy

A. Producers- use sunlight to make food (plants and some protists)

B. Consumers- eat other organisms for food • Herbivore – eat producers• Carnivore – eat meat• Omnivore – eat meat and producers• Scavenger – feed on dead animals

C. Decomposers- break down dead organisms (fungi and some bacteria - recycle nutrients)

• Trophic Level one is always a producer

• Level two is the primary consumer

• Primary Consumers are herbivores or omnivores, because they eat producers.

Producer

Primary Consumer

Secondary Consumer

Tertiary Consumer

Competition

Two or more organisms try to use the same limited resource

What two organisms compete for mice as an energy source?

Transfer of energyName all of the producers from the food web

Name all of the primary consumers

Which of the primary consumers are herbivores?

Which of the primary consumers are omnivores?

Secondary ConsumersSecondary Consumers are in the third trophic level

Name the secondary consumers above

First

Second

Third

Food webs show relationships

• Competition- when two or more organisms try to use the same limited resource.

Are their any organisms competing in the food web?

Importance of predator prey RelationshipsName four prey

of the lobster?

How would over fishing affect this population?