Unit 1: Energy in Ecosystems Part 1

A food chain shows organisms that eat each other in a line.
The arrows show the flow of energy

• Sun - ultimate source of energy in Earth's ecosystems

• Producer - always the first organism in a food chain

• Primary Consumer - organism that eats a producer

• Secondary Consumer - organism that eats a primary consumer

• Tertiary Consumer - organism that eats a secondary consumer

A food web is a more complex model that shows many feeding relationships in an ecosystem.

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Food Webs

There are many food chains shown in one food web.

For example:
grass → rabbit → hawk

grass → mouse → owl


grass → grasshopper → bird → snake → hawk

Practice identifying the feeding relationships in a food web.

For example:
grass → grasshopper → bird → snake

Grass is a producer
Grasshopper is a primary consumer
Bird is a secondary consumer
Snake is a tertiary consumer

Some food webs can look a bit different.
This aquatic ecosystem shows plankton as the producer.

Remember that the arrows show the flow of energy.

For example:
plankton → krill → Antarctic cod → leopard seal