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 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.
What is this process called? Photosynthesis 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. 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. ) 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 path 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?!?! 3 rules for making a food chain… 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).
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)!!
Now try drawing your food chain (WITH NEW EXAMPLES!) 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 the complicated flow of energy in an ecosystem Food webs show us the complicated flow of energy in an ecosystem. Food webs are really a whole bunch of food chains. They show us that organisms eat more than just one thing, and the feeding relationships between organisms in the ecosystem.
Marine Food Web
Compare Food Webs & Food Chains Food webs are made of many food chains Food webs show the transfer of energy in the ENTIRE ecosystem
Producers (photosynthesis) 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
Meaning… only 10% of the energy is transferred. Producers (Plants) Primary Consumers Secondary Consumers Tertiary Consumers 100% 10% 1% 0.1% There is a 90% energy loss between trophic levels.
Why are there so few at the top? Read these questions, then look at your Trophic Level Pyramid 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? There is not enough energy to support lots of top consumers.
Is there one level that is more important than the others? Why? Read these questions, then look at your trophic level pyramid 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 – how much is passed on? How much is lost? 10% is passed on between trophic levels 90% is lost between trophic levels