Grade 7 Notes Section 2.1

The Transfer of Energy in Ecosystems

Energy Transfer

• Food chains show how energy is transferred through an ecosystem
• The energy transfer in ecosystems begins with the Sun and producers

For example:

Sun                  Producers                     Herbivore and Omnivores                 Carnivores and Omnivores

• Only stored energy is transferred to the organisms at the next level
• About 10% of energy consumed by an organism is stored in its tissues
• A lot of energy consumed is used for living, growing, and given off as heat

Types of Consumers

	Primary Consumers	Secondary Consumers	Tertiary Consumers
What they eat	Producers	Primary Consumers	Secondary Consumers
Also known as	Herbivores and Omnivores	Carnivores and Omnivores	Carnivores and Omnivores
Examples	Rabbits Cows	Foxes Raccoons	Owls Wolves, Bears

Energy Pyramids

·        Energy pyramids show the amount of energy transferred in a food chain

·        There are fewer organisms as you  move up the pyramid

·        Only 10% of energy is passed on to the next level

·        Less energy passed on means fewer organisms

Food Webs

·        Food webs show interconnected food chains

·        They show a complex network of feeding relationships

·        More accurate model than a simple food chain