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. Fourth Trophic Level Third Trophic Level Second Trophic Level First 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 Producers- use sunlight to make food (plants and some protists) Consumers- eat other organisms for food Herbivore – eat producers Carnivore – eat meat Omnivore – eat meat and producers Scavenger – feed on dead animals Decomposers- break down dead organisms (fungi and some bacteria - recycle nutrients)

Trophic Level one is always a producer Primary Consumer Producer Trophic Level one is always a producer Level two is the primary consumer Primary Consumers are herbivores or omnivores, because they eat producers. 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 energy Name all of the producers from the food web

Which of the primary consumers are herbivores? Name all of the primary consumers Which of the primary consumers are omnivores?

Secondary Consumers Secondary Consumers are in the third trophic level First Name the secondary consumers above

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 Relationships How would over fishing affect this population? Name four prey of the lobster?