EcologyEnergy Flow

Producers• Sunlight is the MAIN source of energy for all

life on Earth• Only plants, some algae, and certain

bacteria can capture energy from the sun and convert it into a USABLE form of energy

• Autotrophs – organisms that capture and convert the sun’s energy• Also called PRODUCERS!

Producers

• Producers use a process known as photosynthesis

• Light energy is used to convert carbon dioxide (CO2) and water (H2O) into oxygen (O2) and carbohydrates (C6H12O6)

Carbon Dioxide + Water + Sunlight Carbohydrates + Oxygen

Producers• Some autotrophs can produce food without

light by using a process called chemosynthesis

• Chemical energy is used to convert hydrogen sulfide (H2S), carbon dioxide (CO2), and water (H2O) into carbohydrates (C6H12O6) and sulfur compounds (H2SO4)

• This usually occurs in remote locations (e.g. ocean floor and hot springs)

• Bacteria are the most common autotrophs that use chemosynthesis

Producers

• Photosynthesis• “photo-” means

“light”• Uses light for energy

• Chemosynthesis• “chemo-” means “chemicals”• Uses chemicals for energy

Consumers• Many organisms cannot use sunlight as food

• Animals, fungi, some bacteria, some protists• These organisms must consume other organisms

to obtain energy• These organisms are called heterotrophs

• Also called CONSUMERS!

Consumers• Five (5) main types of heterotrophs:

1) Herbivore – consumes only plants2) Carnivore – consumes only animals

• Some scavengers are considered carnivores3) Omnivore – consumes plants and animals4) Detritivores – consumes decaying and rotting

material (such as rotting leaves, etc.)• Some scavengers are considered detritivores

5) Decomposers – breaks down organic (living) material• Finishes the job that scavengers and detritivores

start

Feeding Relationships

• Energy flows through an ecosystem in one direction

Sun/ Inorganic Compounds

Autotrophs Heterotrophs

Feeding Relationships• Food Chain –

series of steps in which organisms transfer energy by eating and being eaten• Shows one-way

flow of energy in an ecosystem

Feeding Relationships• Most feeding relationships are more complicated

than a food chain• Food Web – network of complex interactions and

feeding relationships in an ecosystem

Terrestrial Food Web

Marine Food Web

Feeding Relationships• Trophic Levels – steps in the food chain/web

• Producers – 1st trophic level• Consumers – 2nd, 3rd, or higher trophic levels

• Each consumer depends on the previous trophic level

1st Trophic Level

1st Trophic Level

2nd Trophic Level

2nd Trophic Level

3rd Trophic Level

3rd Trophic Level

4th Trophic Level

4th Trophic Level

5th Trophic Level

5th Trophic Level

Ecological Pyramids

• Ecological Pyramid – diagram that shows the relative amount of energy or matter contained within each trophic level of a food chain/web

• 3 Types• Energy Pyramid – shows the relative amount of

energy available at each trophic level• Biomass Pyramid – shows the amount of living

organic material at each trophic level• Pyramid of Numbers – shows the relative number of

individual organisms at each trophic level

Energy Pyramid• Only part of the energy that is stored at one

trohpic level can be passed to the next trophic level• 10% of the energy at one level is transferred to the next

• Why isn’t ALL the energy transferred to the next level?• The other 90% is used by the organism at the previous

level

Energy Pyramid

Light or Chemical Energy

Biomass Pyramid• Biomass – total amount of living tissue within a

given trophic level• Usually expressed in terms of grams of organic matter per

unit area

• Biomass pyramid represents the amount of potential food available for each trophic level in an ecosystem

Biomass Pyramid

10 %

10 %

10 %

10 %

Pyramid of Numbers• Based on the actual number of individuals at each

trophic level• Does not always resemble the shape of a pyramid

• Ex: tree may be at bottom of “pyramid”

Pyramid of Numbers

Pyramid of Numbers