Ecosystems and Their Interactions

LT: Food Webs & Energy Flow in Ecosystems

All living things ultimately get their energy from the SUN (some directly and some indirectly).

One exception to the rule:

Chemoautotrophs!!

- Use chemicals to make energy

- Example: Bacteria found in the deepest parts of the ocean feed off of hydrogen sulfide released from deep sea vents.

Plants, algae and some bacteria can Plants, algae and some bacteria can capture solar energy and store it as food.capture solar energy and store it as food.

What is this process called?What is this process called? PhotosynthesisPhotosynthesis

Producers are organisms that produce their own energy through photosynthesis. They are also known as autotrophs. Examples?

Consumers are organisms that get their energy by eating other organisms. They are also known as heterotrophs. Examples?

Consumers can be identified more specifically:

Primary Consumer (1 consumer) – eats producers

Secondary Consumer (2consumer) – eats primary (1) consumers

Tertiary Consumer (3 consumer) – eats secondary (2) consumers

Quarternary Consumer (4°consumer) – eats secondary (2) & tertiary (3) consumers

Let’s plug some organisms into these names to make more sense of this:

Grass is a producer because it makes its energy from the sun.

A lady bug is a primary consumer (or 1 consumer) because it eats the grass which is a producer.

A frog would be a secondary consumer (or 2 consumer) because it eats the lady bug which is a primary consumer.

A snake would be a tertiary consumer (or 3 consumer) because it eats the frog which is a secondary consumer.

And so on…

(We will come back to these examples later!)

There are four types of consumers (not 1, 2, 3, etc.). Can you guess what they are?

Herbivore – only eats plantsCarnivore – only eats animalsOmnivore – eats both plants and animalsDecomposer – breaks down dead organic material

How do you show the energy transferred through (in) ecosystems?

food chains and food webs

Food chains show the sequence in which energy is transferred from one organism to the next as one eats the other.

Marine Food Chain

So how do you make a food chain?!?!

1. Choose an ecosystem that you want to focus on.

(You wouldn’t want to put together a rattlesnake, a penguin and a black bear because they obviously don’t live together in the same ecosystem!)

2. Choose an organism at each level (producer, primary consumer, secondary consumer, tertiary consumer, etc.) that would actually eat the one before it.

3. Place your arrows correctly. Arrows ALWAYS point towards where the energy is GOING (towards who is doing the eating).

3 rules for making a food chain…

We actually already made a food chain earlier!

Remember this?Grass is a producer because it makes its energy from the sun.A lady bug is a primary consumer (or 1 consumer) because it eats the grass which is a producer.A frog would be a secondary consumer (or 2 consumer) because it eats the lady bug which is a primary consumer.A snake would be a tertiary consumer (or 3 consumer) because it eats the frog which is a secondary consumer.

Well it’s a food chain!

Sun Grass Lady Bug Frog Snake

***Notice that the arrows are pointing to where the energy is going (not what is eating what)!!

FOOD CHAIN CHALLENGE:Can you think of a food chain? Do you think you can draw it (with pictures or words)? Do you think you could draw it with the arrows going in the right direction?

***Remember, describe the direction the arrows are pointing by saying “producer to primary consumer” or “secondary consumer to tertiary consumer.” NOT “left to right” because food chains/webs can be drawn in any direction.

Check it out:

Sun Grass Lady Bug Frog Snake

Snake Frog Lady Bug Grass Sun

They both mean the same thing!

You could even draw them from top to bottom or bottom to top! Just make sure the arrows are pointing in the right direction (towards where the energy is GOING).

Now try drawing your food chain (WITH NEW EXAMPLES!) on your graphic organizer!

Food webs show us what an ecosystem really looks like. Food webs are really a whole bunch of food chains. They show us that organisms eat a lot more than just one thing.

Marine Food Web

Compare Food Webs & Food Chains

a. Food webs are made of many food chains

b. Food webs show the transfer of energy in the ENTIRE ecosystem

TROPHIC LEVEL PYRAMID (trophic=energy)

Each step in the transfer of energy through an ecosystem

is known as a Trophic Level.

Producers (photosynthesis)

Primary Consumers

Secondary Consumers

Tertiary Consumer

There is a 90% energy loss between trophic levels.

Producers (Plants)

Primary Consumers

Secondary Consumers

Tertiary Consumers

100%

10%

1%

0.1%

Meaning… only 10% of the energy is transferred.

Read these questions, then go back to the last slide and see if you can answer them.

Why do you think there are so many organisms on the bottom of the pyramid?What does this mean?

They provide all of the energy for the entire ecosystem; they are the basis of the ecosystem

Why are there so few at the top? What does this mean?

There is not enough energy to have lots of top consumers.

Read these questions, then go back to the last slide and see if you can answer them.

Is there one level that is more important than the others? Why?

Producers are the most important because they provide energy for the entire ecosystem.

Energy Transfer

___10_____ % is passed on between trophic levels

____90____ % is lost between trophic levels