Ecosystems and Their Interactions Energy Flow in Ecosystems

The ultimate source of energy for all living things is the sun.

Plants, algae and some bacteria can capture solar energy and store it as food. What is this process called? Photosynthesis

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

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

Consumers can be identified more specifically: Primary Consumer (written shorthand: 1  consumer) – eats producers Secondary Consumer (written shorthand: 2  consumer) – eats primary (1  ) consumers Tertiary Consumer (written shorthand: 3  consumer) – eats secondary (2  ) consumers This can continue (quaternary (4  ) consumer, etc.) as long as there are more organisms that eat the last…

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!)

Important: All living things get energy from the sun, some directly and others indirectly.

One exception to the rule: Deep ocean communities that have a bacteria that make energy from Hydrogen Sulfide released through fissures in the ocean floor.

There are four types of consumers (not 1 , 2 , 3 , etc.). Can you guess what they are? Herbivore – only eats plants Carnivore – only eats animals Omnivore – eats both plants and animals Decomposer – 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?!?!  First of all, 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!)  Then, choose an organism at each level (producer, primary consumer, secondary consumer, tertiary consumer, etc.) that would actually eat the one before it.  Then, think about which direction your arrows need to point (arrows ALWAYS point towards where the energy is GOING). (See next few slides for more information.)

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)!!

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). Try drawing your food chain on a scrap piece of paper.

Food webs show the many feeding relationships in an ecosystem.

Marine Food Web

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

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? Why are there so few at the top? What does this mean? Is there one level that is more important than the others? Could you compare this pyramid to something else to prove your point?

There is a 90% energy loss between trophic levels. Producers (Plants) Primary Consumers Secondary Consumers Tertiary Consumers 100% 10% 1%.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. Could you explain what the pyramid in the last slide means to someone else? Look at how much energy is lost and how much is passed on between trophic levels. Do the %’s make sense in the pyramid? Could you explain it? ASK if you have questions!!!