Food Webs and The Energy Pyramid Ms. Twardowski Science 8 Tan

Hmmm…What’s the difference between a “Food Web” and a “Food Chain”?  Discuss with your partner.  Write down your answer.  Be prepared to share out!

Food for thought! With your partner, write down the differences between: A herbivore, a carnivore, and an omnivore.

Food Webs  All populations living and interacting together compose an ecosystem.  ALL ecosystems exchange materials with one another and ALL influence one another.

Food Webs  The size of populations change as a result of the interrelationships among organisms.  ALL organisms, including humans, are part of food webs and depend on each other!

Producers  Producers ‘produce’ (make) their own food from sunlight. WHAT process is this called? Hint: Starts with a ‘P’.  ALL producers are plants, trees, vegetation, flowers, etc.  Producers have the largest population.

Consumers  Consumers ‘consume’ (eat) producers and/or other consumers.  There are three levels of consumers: Primary, Secondary, and Tertiary.

Red = False/No Green = True/Yes  Producers make their own food from sunlight.

Red = False/No Green = True/Yes  Producers have the smallest population in an ecosystem.

Consumers  Primary Consumer: Eats vegetation only! Herbivore.  Secondary Consumer: Eats Primary Consumers. Carnivores.  Tertiary Consumer: Eats Primary and Secondary Consumers.

Interactions  Predator-Prey. For example, when a black rat snake eats a field mouse - the snake is the PREDATOR and the mouse is the PREY.  Producer-Consumer. For example, when a field mouse eats corn - the corn is the PRODUCER and the mouse is the CONSUMER.

“Top Predators”  The Tertiary Consumer is at the top of the food web.  WHY? The Tertiary Consumer has no natural predator.  Tertiary Consumers have the smallest population in the ecosystem.

Red = False/No Green = True/Yes  There are three levels of Consumers: Primary, Secondary, and Thirdary.

Food Webs  A food web is made when organisms consume (eat) other organisms to get the nutrients and energy they need to survive.  IMPORTANT: The arrows show which way the energy from the Sun flows!!!

How to make a food web.  The sun goes at the top and supplies energy to the producers..  The producers go on one line.  The primary consumers go on one line.  The secondary consumers go on one line.  The tertiary consumers go on one line.  The decomposers go on one line.  The arrows show the flow of energy and go from the organism that is eaten to the organism that eats it!

Make a food web (formative)…  Directions: With your shoulder partner, make a food web using the following organisms:  Sun, rat snake, field mouse, owl, corn, flower, toad, small butterfly, rabbit, grass, red fox, mushroom, mold, and bacteria.  Be sure to show: flow of energy (arrows) going in the right direction.

Energy Pyramids  The energy pyramid is a way to classify levels of energy that pass through an ecosystem. The higher up the pyramid you go, the fewer organisms belong in that group…WHY?...

The Energy Pyramid and the 10% Rule… ALL organisms need energy to live (walk, breathe, fly, hunt, etc.). ALL organisms need energy to live (walk, breathe, fly, hunt, etc.). All organisms use about 90% of their energy just to carry out daily functions. All organisms use about 90% of their energy just to carry out daily functions. 10% Rule: The other 10% of energy gets stored in the organism and/or passed on to a predator. 10% Rule: The other 10% of energy gets stored in the organism and/or passed on to a predator.

The Energy Pyramid (the levels) Producers: Get 100% of their energy from the Sun (photosynthesis). Consumers: 10% of the prey’s energy is passed on to the predator. (Primary Consumers, Secondary Consumers, and Tertiary Consumers)

Example  Note the pyramid on the left. At the bottom are thousands of plankton. As you move up the pyramid, all those plankton end up supplying energy to just one shark!

Red = False/No Green = True/Yes  90% of the prey’s energy is passed on to the predator when the prey is eaten. This is known as the 90% Rule.

The math involved in an Energy Pyramid.  A very important part of understanding the energy pyramid is seeing how the energy transfers from the bottom level to the top level.  You will need to know how to calculate percents and how to do subtraction. (You can use a calculator.)

 How much energy gets passed on to the hawk?  DRAW THIS TABLE IN YOUR JOURNAL. Sunlight Produces 10,000 units of Energy Plants get= Plants use 90%= (to live, grow, reproduce) Rabbits get= (passed on from plants) Rabbits use 90%= (to live, grow, reproduce) Fox gets= (passed on from rabbit) Fox uses 90%= (to live, grow, reproduce) Hawk gets=