Ecology

…the study of how organisms interact with each other and their

environments

…the study of ……..OUR house…..

ENERGY FLOWS

MATTER CYCLES

FACTORS INTERACT

ENERGY FLOWS

Trophic Levels• Energy moves from one

organism to another when it is eaten

• Each step in this transfer of energy is know as a trophic level

• The main trophic levels are producers, consumers, and decomposers

When energy flows as organic

matter through the trophic

levels of an ecosystem, MUCH

of it is LOST at each link in a

food chain.

Why?CLUE

When you burn energy to run a mile in gym where does that energy come from?

Transfer of Energy• When a zebra eats the grass, it does

not incorporate all of the energy the grass has into its body (much of it is not digested and used for energy to live)

Transfer of Energy• When a lion eats a zebra, it

does not keep all of the energy from the zebra in its body….

Plant material eaten by

caterpillar100 kilocalories (kcal)

50 kcalFeces

15 kcal

Growth

35 kcalCellular respiration

Does all the energy this caterpillar eats get passed to the bird who eats him?

Transfer of Energy• No organism EVER keeps all of

the energy from the organism they just ate

• Only ~10% of the energy from one trophic level is really transferred to the next – this is called the 10% law

Ecological Pyramid• An ecological pyramid shows

the relationship between organisms different trophic levels in an ecosystem

• Shows the relative amounts of energy or matter and number of organisms contained at each trophic level

Ecological Pyramid

Biomass• The total mass of the organic

matter at each trophic level is called biomass

• Biomass is just another term for potential energy – energy that has yet to be eaten and used.

Decomposers:What is a decomposer and what do they

do? What trophic level would you put them at?

– Derive their energy from the dead material left by all trophic levels

– Are often left off of most pyramids and food chain diagrams

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?