1. Food Chains and Food Webs
Lesson 4
Food Chains and Food Webs

2. Energy Roles
An organism’s energy role in an ecosystem may be that of a producer, consumer, or decomposer.

3. Producers • An organism that can make its own food is a producer.
• Also called a Autotroph
• Source of all food in an ecosystem.
• Capture energy from sunlight and stores it as food energy.

4. Consumers
• Consumers are heterotrophs , or living things that cannot make food for themselves.
• A food chain contains several kinds of consumers, each of which occupies a different trophic level.
• There are 3 types: Herbivore, carnivores, omnivores

5. Consumer Trophic Levels
• Primary consumers eat producers (herbivores)
Only eat plant tissue

6. Consumer Trophic Levels
• Secondary consumers eat primary consumers (carnivores & omnivores)
Carnivores
Eat mostly animal tissue
Omnivores
Eat plant and animal tissue
• Tertiary consumers eat secondary consumers (carnivores)

7. Consumer Trophic Levels
• Scavengers are carnivores that feed on the bodies of dead organisms.

8. Consumers Decomposers
Special group of consumers that break down organic matter and release the nutrients back into the ecosystem.
They do not eat the organic material directly; they release enzymes which break it down which they then absorb.
Fungi and bacteria
Detritivore
Consumers that feed on Organic Matter
The remains of dead organisms and animal waste
Snails, worms, maggots.

9. Trophic Levels Primary Consumer • Herbivores • Eat producers
Secondary Consumer
• Carnivores & Omnivores
• Eat primary consumers
• Eat primary consumers & producers
Tertiary Consumer
• Carnivores
• Eat secondary consumers

10. Decomposers
•Help break down wastes and dead organisms and return the raw materials to the environment
• Bacteria and fungi

11. Food Chains
• Series of events where one organism eats another and obtains energy.
• The chain always begins with the sun
• First organism in chain is the producer.
• The second organism is the consumer that eats the producer.

12. Sun — Plankton —Crab—Seal— Orca
This is only one possible chain in a marine ecosystem.

13. Come up with an example to fill in the blocks of a food chain in two different ecosystems.

14. Food Webs • Consists of many overlapping food chains in an ecosystem.
• Some organisms may play more than one role by changing consumer levels.

15. What happens in a food web if one or more of the organisms disappear?

16. Energy Pyramids
• A diagram that shows the amount of energy that moves from one feeding level to another in a food web.
• Represented in a triangle with the most energy at the producer level.
Energy Loss and Use
• 10% of energy transferred to next higher level.
• 90% of energy is used by organisms’ life processes.
• Due to energy loss, ecosystem cannot support many feeding levels.