Energy in Ecology

How is energy transferred?

Watch in intro clip…

• Note what the video clip says about the following:– Food chains– Food webs– Trophic levels– Any misconceptions– ENJOY, LISTEN, WATCH, AND LEARN!– http://www.youtube.com/watch?v=cWh-XKhh8xo

Energy• All ecosystems must transfer energy.

• Energy flows in ONE DIRECTION

• Heat Energy (Sun) changes into chemical energy (locked in organisms)

• When we eat other living things, the energy is passed down to us

• All energy transfers originate from the

SUN

How does energy flow?• Energy flows in one direction. From sun

to the producers to the consumers

• Producers/ Autotrophs (plants)= organisms that make their own food through photosynthesis to obtain energy.

• Consumers/ Heterotrophs organisms that consume other organism for energy. Also known as HETEROTROPHS

• Heat Energy (sun) is converted to Chemical Energy (food) through energy flow.

• Some energy is lost to heat at each transfer

Overall Energy In Ecosystems

SUN PRODUCERS CONSUMERS

What are some ways we can see how energy is transferred?

• Ecological Food Chains and Webs• Ecological Pyramids• Energy Pyramids• Biomass Pyramids• Numbers Pyramids

Food Chains and Webs

• Food Chain: shows the passing of energy from one organism to another (by eating or being eaten)

• Food Web: shows more than one transfer of energy (feeding relationship)

Understanding a Food Chain

What are the producers in this chain?

What are the secondary consumers?

Where is the least energy in this chain?

What type of feeding organism is the squid?

Food Chains and Webs•Producers are at the beginning or base of food chains and webs= (photosynthetic organisms)

•Herbivores (primary consumers)= organisms that get energy only from plants (grasshopper)

•Carnivores (secondary/tertiary consumers)= organisms that feed on other animals (owl)

•Omnivore= organism that feeds on both plants and animals

•ARROWS INDICATE THE TRANSFER OF ENERGY, NOT WHAT EATS WHAT.

•The most of the energy is at the producer level. Least is at the top consumer level•Trophic Levels: each step or level in

a food chain or web that shows transfer of energy

Other Organisms that May Not Be Represented on Webs/Chains

• Decomposers/detritivores: organisms that feeds off of and breaks down dead matter in order to return nutrients to the soil (bacteria, fungi, worms)

• Scavengers: an animal that feeds off of dead organisms rather than or in addition to hunting live prey. Ex: vultures, hyenas, wolves.

Ecological Pyramid• Visually shows the relative amount of energy contained within each trophic level

•Most energy is at the producer level and decreases up the pyramid

•Shows organized trophic levels

1st trophic level

2nd

3rd .

4th

Energy Transfer Rule

• Beginning at the producer level, each level transfers ONLY 10% of its available energy to the next level and 90% of energy is lost to heat.

Ecological Pyramid Energy Rule-

Amount of Energy• 100% available at the

producer level• 10% available at the

primary consumer level• 1% available at the

secondary consumer level• .1% available at the tertiary

consumer level• At every level 90% gets lost

to heat

What are Trophic Levels?

• Trophic Levels: organized step or level in a food chain or web that shows transfer of energy

4th

3rd

2nd

1st

Biomass Pyramid

Biomass Pyramid

• Shows the total amount of living tissue or mass within trophic level that is available for energy transfer

Pyramid of Numbers

Pyramid of Numbers• Represents the number

of individuals counted at each trophic level.

• There are less organisms as we move up the numbers pyramid because organisms at higher levels are larger and have more biomass.

Another example of pyramid of numbers

• Major Trend– Amount of organisms

available to transfer energy at each tropic level decreases as we move through the pyramid.

Try a sample pyramid of numbers problem

Organism # of Organism in the Ecosystem

A 32

B 835

C 1292

D 16

Try a sample pyramid of numbers problem

Organism # of Organism in the Ecosystem

A 32

B 835

C 1292

D 16

C

D

A

B

Practice

Food Web Summary Activity• Work with the person sitting next to you to

use the food chains to create a food web using the pictures.

• Follow the instructions on the summary activity to correctly label and answer the questions.

Address the following as well…

Name the organism(s) that hold the most energy in the food web

Name the organism(s) that has the least energy