Feeding Relationships

Give Me Energy or Give Me Death!!!(not quite Patrick Henry)

• All organisms need energy to live.

• 3 Types of Organisms– Producers– Consumers– Decomposers

Producers

• Organisms that make their own food using energy from the sun (photosynthesis) or by other means.

• Ex. Plants, algae, some bacteria

Consumers

• Any organism that gets its food by eating other organisms.

• Types of Consumers– Herbivores

• Plant eaters• Ex. Rabbit

– Carnivores• Meat-eaters• Eat herbivores or other carnivores• Ex. Shark, wolves• Scavengers: eat dead things

Consumers

• Types of Consumers– Omnivores

• Eat both producers and other consumers

• Ex. Raccoon, bears, most people

Decomposers

• Organisms that feed on the remains or wastes of other organisms.

• Recycle the nutrients back into the soil

• Often left out of food chain

• Ex. Bacteria and fungi

Food Chain

• Traces the path of energy as it moves from one organism to the next in an ecosystem.

• Shows only 1 energy path in an ecosystem.

Notice how all energy begins with the SUN

Producer=Photosynthesis

Consumers

Food Chain

Producer

Primary Consumer

Secondary Consumer

Tertiary Consumer

Decomposers

Food Chain Terminology

• Producer– Photosynthetic organism that gets energy from sun.

• Primary Consumer (1°)– First to feed.– Herbivore– Most energy gets used, some gets lost as heat, and

some gets passed onto the secondary consumer.

• Secondary Consumer (2°)– Eats the primary consumer (herbivore)– Carnivore, omnivore, or scavenger

Food Chain

• Tertiary Consumer (3°)– Eats the 2° consumer

• Decomposer– Eats the remains of

the consumers.

– Obtains the little energy that is left from the consumers.

Food Web

• A system of several overlapping food chains.• Provides a more complete picture of the flow of

energy in an ecosystem.

Prickly PearCactus

Mesquite

Producers

First-levelConsumers

Second-levelConsumers

Third-levelConsumers

DesertCottontail

Woodrat

Weasel

Bobcat

Hawk

Energy Flow

• As energy is passed from organism to organism it is used to carry out cell processes and some is lost to the environment as heat.

• 10% Rule– Only about 10% of the energy present at one feeding

level is passed to the next feeding level.

• Energy Pyramid– Another way of showing the transfer of energy from one

level to the next.

Energy Pyramids Show

• That the amount of available energy decreases down the food chain

• It takes a large number of producers to support a small number of primary consumers

• It takes a large number of primary consumers to support a small number of secondary consumers

10% Rule & Energy Loss

Summary Questions

• Name the three energy roles of organisms in an ecosystem. How does each type of organism obtain energy?

• How does the amount of available energy change from one level of an energy pyramid to the next level up?

• Name and define the four types of consumers.

• What is the source of energy for most ecosystems?

• Why are food webs a more realistic way of portraying ecosystems than food webs?