Food Chains, Webs, and Pyramids

Ecosystems are divided into different sections called trophic levels Each trophic level represents a transfer of energy. –For Example, energy is transferred from the prey to the predator

Trophic Levels Producers: Organisms that create energy in an ecosystem –Most fundamental trophic level –Absorb energy from the sun and convert it into chemical energy by photosynthesis –Usually plants and algae

Consumers: Organisms that can’t produce their own energy –Energy comes from producers –Different types of consumers:

Primary Consumers: eat producers (plants) for energy (herbivores) Secondary Cosumers: feed on primary consumers (carnivores or omnivores) Tertiary Consumers: feed on secondary consumers (carnivores or omnivores)

Decomposers: get energy by breaking down the dead remains of other living things –Includes some bacteria, fungi, and insects

Demonstrating Energy Changes Food Chain: simple diagram of how energy flows. –Arrow points to organism gaining energy (the one that is eating) –EXAMPLE: –Grass  rabbit  snake  hawk

Food Web Food Web: Shows a network of connected food chains

Food Web

Energy Pyramid The flow of energy creates an energy pyramid –Each level of the pyramid uses energy less efficiently than the previous level.