Nov. 25 – Energy Flow, Food Webs and Ecological Pyramids

Learning Goals:

• Understand how energy from the sun flows through all life on Earth.
• Understand how to organize organisms into trophic levels and ecological pyramids.

Success Criteria:

• You can identify if an organism is a producer or consumer.
• You can describe the way organisms acquire energy necessary to survive.
• You can organize organisms into trophic levels.

We began by looking at energy from the sun.

In the most direct way, sunlight can be used to produce heat and light fires.  It can also accidentally melt cars!

Parts of his car melted when sunlight reflected off the curved building and focused on his car.

Nature has found ways to take energy from the sun and convert it into chemical energy which is necessary for life.

Plants can turn sunlight into chemical energy in the form of sugars.

Plants are considered producers because they create their own food from sunlight, water and carbon dioxide.

Humans and other organisms take in the oxygen and chemical food energy (sugars, glucose, carbohydrates, etc.) to produce energy, water and carbon dioxide.

Organisms that don't photosynthesize are considered consumers.  You can further divide the consumers into different trophic levels, depending on what they consume.

Food webs are diagrams used to show how energy flows throughout an ecosystem.  They can become quite complex.

Ecological pyramids are yet another way to show the relationships among different organisms.  Each level of the pyramids refers to a different trophic level.

An energy pyramid shows the amount of energy available at each level.

A number pyramid shows how many organisms are in each level.  These pyramids might be inverted in shape.

Refer to the handouts and your textbook, Chapters 2.4 and 2.5 for further details on all these topics.

Handouts:

• Energy Flow in Ecosystems 
• Food Webs and Ecological Pyramids

Homework:

• Continue studying for your test on Wednesday!

Here is a video showing a food web in action in unexpected and dramatic ways.  It involves lions, crocodiles and water buffalos.  Spoiler alert: it all works out well for the baby water buffalo in the end, but this case is very rare.