Energy Flow Pyramids and Trophic Levels

Does all the energy this caterpillar eats get passed to the bird who eats him?

Plant material eaten by caterpillar

100 kilocalories (kcal)

Feces

50 kcal

Growth

15 kcal

Cellular respiration

35 kcal

TROPHIC LEVELS

Determined by the organism’s source of energy

Organisms are identified by their trophic level

according to their name.

1. Autotrophs

2. Heterotrophs

3. Decomposers

Decomposers are a specific type of heterotroph.

1. AUTOTROPHS:

• Capture energy from the sun (photosynthetic) or

inorganic molecules = chemicals

(chemosynthetic) and converts it into usable

energy.

• Also known as PRODUCERS – produces food (make energy storing molecules),

• Eg. Plants, algae and some kinds of bacteria

2. HETEROTROPHS- • CONSUMER

– obtains the energy to build their molecules by

consuming plants or other organisms

Includes not only primary, secondary, tertiary

(etc.) consumers, but also include:

decomposers and detritivores

DECOMPOSERS

A specific type of heterotroph

Can be one of two types:

-Scavanger/Detritivore: Eats dead organisms (carcasses) or detritus (dead organic matter)

Eg. Bear, Dog, Vulture, Crab, Worm, Bacteria

-Saprotroph: Digests matter, extracellularly (outside the cell) by spitting enzymes out and then absorbing the digested material.

Eg. Fungi such as mushrooms

Pyramid Models:

graphs which illustrate the trophic levels in a community.

Energy Pyramid Model

• Organisms convert food (glucose) into energy.

• This energy is given off as heat which is lost to space.

• Energy is a one way path. It is not a cycle.

Energy Pyramid Model

• An energy pyramid is a diagram that compares energy used by producers, primary consumers, and other trophic levels.

• As a rule each trophic level receives only 10% from the trophic level below.

• In other words each trophic level loses 90% heat to the atmosphere.

Energy Pyramid Model

Producers: 123,000 KJ

Primary Consumers: 12,300 KJ

Secondary Consumers: 1,230 KJ

Tertiary Consumers:

123 KJ

Pyramid of Biomass

• Biomass is the mass of organisms minus water.

• Biomass refers to the amount of carbon and other trace elements in an organism’s body contains.

Illustration of the number of organisms at each level

How can more people be supported on Earth when there is a limited supply of resources?

It depends on what they are eating.