ENERGY FLOW IN ECOSYSTEMS Chapter 2.1 ENERGY FLOW IN ECOSYSTEMS

Energy Roles Every organism has a role in the ecosystem. For example: a bird eats worms and seeds or a shark eats small fish. The bird is a herbivore and the shark is a carnivore.

3 energy roles in an ecosystem Producers Consumers Decomposers

Producers Producer is an organism that makes its own food. On land, the main producers are plants. In lakes and oceans, the main producers are algae and phytoplankton.

Consumers Herbivore Carnivore Omnivore Consumers – are animals that eat other living things. There are 3 kinds of consumers: _________: animal that only eats plants _________: animal that only eats animals __________: animal that eats both animals and plants Herbivore Carnivore Omnivore

Decomposers Decomposers are organisms that break down waste and dead organisms and return raw materials to the ecosystem Examples of decomposers are: bacteria and mushrooms

Interactions between organisms Food Chain Food Web

Levels

Food Chain _________: is a simple chain (way) of showing how the energy from food moves through populations of organisms in a community.

Simple Food Chain

Food chain

Food Web _________: is a complex way of showing how food chains are related

Third level consumers Second level consumers First level consumers Producers Decomposers

Energy pyramid Pyramid - Energy pyramid: a way of showing how energy moves through a food web. Pyramid -

Energy pyramid The most energy is available at the producer level of the pyramid. As you move up the pyramid, each level has less energy available that the level below. The lower level has 10 x more energy than at the next higher level.

Energy pyramid Only about 10% of energy is transferred to the next level. The other 90% is used for the organism’s life processes (like breathing, running, mating, eating etc) or is lost as heat. Since 90% is lost at each level, there is not enough energy to support many organisms at a higher level; resulting in a fever number of consumers at the top of pyramid.

Checking concepts: In this picture, what organism is being eaten by snake? What organism is eaten by a mouse?

What are producers?

In this picture, which organisms eat a bird?

What are three kinds of consumers?

Thinking critically: Minnows are small fish that eat plant materials Thinking critically: Minnows are small fish that eat plant materials. Bass are large fish that feed on minnows. Would you expect to find more minnows or more bass in a pond? Why?

What is the difference between a food chain and a food web?

Why are there usually few organisms at the top of an energy pyramid?

Why is the pyramid shape useful for showing the energy available at each of the levels of a food web?

What are decomposers?

Section 2.1 Assessment pg 47 1a. Name the three energy roles that organisms fill in an ecosystem. 1b. How do organisms in each of the three energy roles obtain energy? 1c. Identify the energy roles of the following organisms in a pond ecosystem: tadpole, algae, heron. 2a. What is a food chain? What is a food web? 2b. Why is a food web a more realistic way of portraying an ecosystem than is a food chain?

Section 2.1 Assessment Con’t. 3a. What does an energy pyramid show? 3b. How does the amount of energy available at one level of an energy pyramid compare to the amount of energy available at the next level up? 3c. Why are there usually few organisms at the top of an energy pyramid?