Energy Flow in an Ecosystem Lesson

How Ecosystems Work

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Energy Flow

• Energy in an ecosystem originally

comes from the sun and flows
from producers to consumers
–Producers (make food)
–Consumers (use food by eating

producers or other consumers)

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Producers

• Sunlight-source of

energy for most life
on earth.

• Producers contain

chlorophyll & use
energy directly from
the sun

• Also called autotrophs

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Autotrophs

• Autotroph-organism that can

produce its own food (Ex. plants,
algae, some protists, & some
bacteria

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Niche of a Producer

• Captures energy and transforms

it into organic, stored energy
(glucose)

a. photoautotrophs use light energy

(e.g. photosynthesis in plants)

b. chemoautotrophs use chemical

energy (e.g. cyanobacteria)

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Chemoautotrophs

• Capture energy from

the bonds of inorganic
molecules such as
Hydrogen Sulfide

• Process is called

Chemosynthesis

• Often occurs in deep

sea vents or gut of
animals

Called a Black

smoker (thermal

vent)
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Tube Worms living in Black

Smoker

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Consumers

Heterotrophs that eat other

organisms to obtain energy.

(e.g. animals)

a. Herbivores

–only plants

b. Carnivores

–Only animals

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Consumers

c. Omnivores (Humans)

– plants & animals

d. Detritivores (Scavengers)

– Dead plant & animal remains

(buzzards)

e. Decomposers

– fungi & bacteria

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Feeding Relationships

Energy flows in one

direction

from producers to

different levels of
consumers

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Feeding Relationships

• Food Chain

–Simple energy path through an

ecosystem

• Food Web

–Realistic path through an

ecosystem made of many food
chains

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Food Chain

Producer

Primary
Consumer

Secondary
Consumer

Tertiary
consumer

Quaternary
Consumer

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Name the Producer, Consumers

& Decomposers in this food

chain:

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Food Web

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Trophic Levels

Each level in A food chain or food

web is a trophic level.

a. Producers

–Always first (1st) trophic level

(how energy enters the system)

• Herbivores

–Second (2nd) trophic Level

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Trophic Levels

c.Carnivores/Omnivores

–Remaining trophic levels

Each level depends on the

one below it for energy.

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Ecological Pyramids

Amounts of energy or matter at

each trophic level

May be:
• Energy Pyramid
• Biomass Pyramid
• Pyramid of Numbers

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Energy Pyramid

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Biomass Pyramid

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Pyramid of Numbers

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