2.2 Flow of Energy in an Ecosystem

What is the source of all energy in this ecosystem?

What path does this energy take to get to the hawk?

Autotrophs Also called producersorganisms that use energy from the

sun or energy stored in chemical compounds to manufacture their own food

Examples: plants & Chlorophyll-containing single cell organisms

Heterotrophsalso called consumers organisms that depend on

autotrophs as their source of nutrients and energy

examples: cow, rabbit, wolf

Herbivores

consumers that depend on plants for their food

examples: grazing, seed-eating, algae-eating, plant eating animal

Bees, grasshoppers, elephants

Carnivoresconsumers that kill and eat only

other animals

Scavengersconsumers that eat

animals that are already dead (do not kill for food)

feed on carrion, refuse, and similar dead organisms example:

black vultures

Omnivoresconsumer that eats both plants

and animalsexamples: humans, raccoons,

coyotes, bears

Decomposers

break down dead organisms by releasing digestive enzymes

examples: bacteria & most fungi

Food Chainmodel scientists use to show how

matter and energy move through an ecosystem

arrows represent the levels and the direction the energy is flowing

a food chain consist of three to five links

energy is “lost” as heat at each link

Food Chai

n

Food Web

a network of interconnected food chains

expresses all the possible feeding relationships at each trophic level in a community

a more natural model

Food Web

Ecological pyramid depicts energy conversions in an

ecosystembase = producershigher trophic levels = consumerssource of energy for all ecological

pyramids is energy from the sun; energy is always being replenished

Energy Pyramid

1st trophic level – autotroph1st trophic level

2nd trophic level

3rd trophic level

4th trophic level

Auto-trophs

1st order heterotrophs

2nd order heterotrophs

3rd order heterotrophs

Producer

Carnivore

Omnivore

Herbivores