Food Chains and Trophic Levels!

Models of Energy Flow

• Trophic Levels – is the position an organism occupies in a food chain. It refers to food or feeding.

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• Autotrophs always make up the first trophic level in ecosystems.
• Heterotrophs make up the remaining levels

Models of Energy Flow

• Food chains: A simple model that shows how energy flows through an ecosystem

Part 2: Flow of Energy in an Ecosystem

Food webs:

A model representing the many interconnected food chains and pathways in which energy flows.

Models of Energy Flow

• Ecological pyramids: A diagram that can show the relative amounts of energy, biomass or numbers of organisms at each trophic level in an ecosystem.

Part 2: Flow of Energy in an Ecosystem

Energy Pyramid: An energy pyramid’s shape shows how the amount of useful energy that enters each level — chemical energy in the form of food — decreases as it is used by the organisms in that level.

• Each level above only gets 10% of the energy from below.

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Biomass pyramid

• Biomass is a measure of the total dry mass of organisms in a given area.

Pyramid of Numbers

• Shows the numbers of individual organisms at each trophic level in an ecosystem.

• A vast number of producers are required to support even a few top level consumers.