Food Webs

Community• All organisms inhabiting a particular area

Autotrophs • Producers – self feeding• Produce their own

organic material• Green plants• Called primary

producers

Heterotrophs

•Consumers•Organisms which must

consumer organic material to obtain energy

Consumers• Primary

Consumers

• Secondary Consumers

Primary Producers• Control the rate at which producers

convert sunlight to chemical energy in organic matter, or biomass• Determines the energy budget for

ecosystems

Decomposers

• Also called detritivores• Acquire energy from all trophic levels

waste products and dead material

Food Chain• Pathway of food within a

community• Links energy and nutrients

between producers, consumers and decomposers• Divided into trophic levels

Trophic Structure• Every community

has a trophic structure

• Trophic levels increase as you go up the food chain

•Energy levels decrease as you go up the food chain

• Only approximately 10% of the energy stored at each trophic level is available at to the next level

Food Web

• A series of interconnected food chains

Biomass• A measure of the dry weight of an

organism is a rough measure of the energy it contains• A measure of the population

multiplied by the weight of an average individual in it