Energy Flow in an Ecosystem

Try it...

� Arrange the following organisms to show who eats

whom:

– orca

– cod fish

– krill shrimp

– algae

– leopard seal

All organisms play a role in their ecosystem:

� Producer (Autotroph)

– Make their own food (usually through

photosynthesis, sometimes chemosynthesis)

� Ex: plants (even the Venus Flytrap!)

Origin of the energy…

Sunlight is the ultimate origin of energy used by

life on earth to conduct the business of life.

6CO2 + 6H2O + light energy � C6H12O6 + 6O2

�

All organisms play a role in their ecosystem:

� Consumers (Heterotroph)

– Can’t make its own food

– Gets energy from eating other organisms

1. Herbivores – eats plants

2. Carnivores – eats animals

3. Omnivores – eats plants & animals

• Scavengers – eats dead animals

All organisms play a role in their ecosystem:

� Decomposers

– Break down waste and dead organisms to return

raw materials to the environment

� Ex: bacteria, fungi, worms

Producer or Consumer?

Consumer (herbivore)

Producer or Consumer?

Producer

Producer or Consumer?

Consumer (omnivore)

Producer or Consumer?

Consumer (carnivore)

Food Chain

Food chain – shows one path of the flow of energy in an ecosystem

Order of the food chain:1.Sun – energy source

2.Producer

3.Primary Consumer – eats producers

4.Secondary Consumer – eats primary consumers

5.Tertiary Consumer (apex predator) – eats secondary consumers

6.Decomposer – recycles materials for use by producers

Food web

� model that shows the energy flow through

different organisms in an ecosystem.

� consists of many overlapping food chains

within an ecosystem

FOOD WEB VS FOOD CHAIN

Ecological Pyramid Models

� A pyramid is used to illustrate the structure of

the trophic levels in a food chain.

� 3 types of ecological pyramids:

– Pyramid of numbers

– Biomass pyramid

– Energy pyramid

Pyramid of Numbers

� Typically pyramid shaped, with the largest number of organisms at the producer level:

Compares the number of organisms at each trophic level in a food chain.

Biomass Pyramid

Shows the amount of living matter in a food chain.

� Total dry weight (without water) of organisms in a

food chain

� Mass/Area

– Example: g/m2

Energy Pyramids

Flow of energy

� When an organism eats, it obtains energy,

then uses a lot of energy in life process like

growth and movement.

� This means that only part of their energy is

available to the next organism in the food

web.

Energy Pyramid

� Illustrates the amount of energy that moves from

one feeding level to another in a food chain or web

� The greatest amount of energy is available at the

producer level

– The least amount of energy available to going to be a the top of the food chain.

� Only about 10% of the trophic level’s energy is transferred to the next level.

Energy Pyramids