Food Chain – a model of how energy is passed from organism to organism in a community Energy moves from one organism to the next in a one-way direction Arrows show the direction of energy transfer Because few organisms eat just one kind of food, simple food chains are rare

Who’s who in a food chain? The 1 st link in any food chain is a producer The 2 nd link is usually an herbivore –This is the primary consumer – the first consumer in the food chain The 3 rd link of a food chain is a carnivore or omnivore –This is the secondary consumer – the second consumer in the chain The 4 th link is also a carnivore or omnivore –This is the tertiary consumer – the third consumer in the chain When organisms die in any ecosystem, decomposers feed on them, in order to break down the remains and recycle nutrients

Food Web – a model that shows all the possible feeding relationships among organisms in a community

More on Food Webs Food webs are a more complete model of the way energy moves through a community They are more accurate because they show the many organisms that feed on more than one level in an ecosystem Food webs are like a series of overlapping food chains

Decreasing Number of organisms Decreasing Amount of energy Producer: Primary (1 st ) Consumer: Secondary (2 nd ) Consumer: The pyramid represents energy. As you can see, more energy is available at the base of the pyramid than at its top.

Facts about Energy Pyramids: Energy pyramid - a diagram that shows the amount of energy available at each feeding level in an ecosystem Food chains usually have at least 3 links, but rarely more than 5 This limit exists because the amount of available energy is reduced as you move from one level to the next in a food chain Only about 10% of the energy available is transferred to the next level 90% of the energy is used by the organism (digestion, hunting, breathing, lost as heat)

Energy Pyramids