Catalyst

1. Based on the food chain shown, what would most likely happen to the rat population if another predator began eating snakes?

2. Is the the change in number 1 biotic or abiotic?

3. What could cause a decrease in the grasshopper population?

Agenda

• Catalyst

• Energy Pyramids PowerPoint

• Making an Energy Pyramid

• Energy Pyramid Project

Objectives

• SWBAT distinguish between producers and consumers and autotrophs and heterotrophs

• SWBAT identify the category of organisms and relative amount of energy represented by each trophic level of an energy pyramid

• SWBAT explain how and why energy changes from the base to the top of an energy pyramid.

Energy Pyramids

Biology

Organisms and Energy

• All organisms need energy to survive, and they receive energy from the food that they produce or consume

Energy Flow

• For an ecosystem to exist, there must have constant flow of energy between the organisms of that ecosystem

Energy Pyramids

• Scientists model the flow of energy in an ecosystem with an energy pyramid

• Contains different levels of organisms known as trophic levels

To take notes… • Fill in the example energy pyramid

Producers

• The first trophic level is at the bottom of the pyramid

• Organisms at the bottom of the energy pyramid are known as producers

• Producers are autotrophs—organisms that use energy from the sun to produce food

Producers

• What are some examples of producers/autotrophs?– Trees– Grass– Berries– Nuts– Algae– Phytoplankton

Consumers

• All other organisms in the energy pyramid are consumers

• Consumers are heterotrophs—organisms that obtain energy from the food they consume

Primary Consumers

• Above producers in the pyramid are primary consumers. – 2nd trophic level– These are herbivores

—organisms that consume only plants.

Primary Consumers

• What are some examples of primary consumers/herbivores?– Insects– Rabbits– Deer– Mice– Small fish

Secondary Consumers

• Above the primary consumers in the pyramid are secondary consumers. – These are carnivores

—organisms that consume other animals.

Secondary Consumers

• What some examples of secondary consumers/carnivores?– Frogs– Snakes– Large fish– Foxes

Tertiary Consumers

• Above secondary consumers are tertiary consumers.

• These may be carnivores or omnivores—organisms that consume both plants and animals

Tertiary Consumers

• What are some examples of tertiary consumers?– Hawks– Eagles– Bears– Humans– Sharks

Energy in a Pyramid

• So why do scientists use a pyramid to represent energy in an ecosystem?

• How does a pyramid change from bottom to top?– It gets smaller!

• So does the amount of energy in an ecosystem from producers high level consumers

Energy Changes

• The bottom of the energy pyramid (producers) contains the greatest amount of energy. – 100% of energy originally present in the ecosystem

• The top (tertiary consumers) contains the least amount of energy.– ~0.1% of initial energy

• Energy is lost as heat between trophic levels – ~90% lost as heat between each level– Only 10% of available energy transferred to next level

Summary

Energy Pyramid

If there is less energy available at higher trophic levels, will there be more organisms or fewer organisms as you go up?

Question…

Number pyramids show the population decreasing at higher levels

Number pyramids + Biomass Pyramids

Biomass pyramids show how much food an organism needs to consume to meet its needs.

A biologist finds that there is far more algae (a producer) in an ecosystem than anchovy. What is the reason for this?

>> Check for understanding

Anchovy is a second-order producer, so there is less energy available than there is for producers.

Energy Water Demo

Example: Copy the chain and answer questions in your notes

Grass Insects Rodents Owl

1.Create an energy pyramid.

2.Label each level with the appropriate term and trophic level.

3.Put the names of each organism in the appropriate level.

If there is 1500kcal of energy in the grass, how much energy will be available for the insects?

1500kcal x 0.10 = 150kcal

Exit Ticket

1. What level on the energy pyramid shown has the greatest amount of energy to transfer to the next level?

2. What are the secondary consumers in this example, and are they autotrophs or heterotrophs?

3. Which level receives the least amount of energy from the producers?

4. Why does the amount of energy decrease as you move from the bottom to top of an energy pyramid?