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MLA Full: "The Dirt on Decomposers: Crash Course Kids #7.2." YouTube, uploaded by Crash Course Kids, 23 April 2015,
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We've talked about food chains and how energy moves through an ecosystem, but let's take a step back and see how everything starts... and ends. Decomposers!

This first series is based on 5th-grade science. We're super excited and hope you enjoy Crash Course Kids!

///Standards Used in This Video///
5-LS2-1. Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment. [Clarification Statement: Emphasis is on the idea that matter that is not food (air, water, decomposed materials in soil) is changed by plants into matter that is food. Examples of systems could include organisms, ecosystems, and the Earth.] [Assessment Boundary: Assessment does not include molecular explanations.]

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Executive Producers: John & Hank Green
Producer & Editor: Nicholas Jenkins
Cinematographer & Director: Michael Aranda
Host: Sabrina Cruz
Script Supervisor: Mickie Halpern
Writer: Jen Szymanski
Consultant: Shelby Alinsky
Script Editor: Blake de Pastino

Thought Cafe Team:
Stephanie Bailis
Cody Brown
Suzanna Brusikiewicz
Jonathan Corbiere
Nick Counter
Kelsey Heinrichs
Jack Kenedy
Corey MacDonald
Tyler Sammy
Nikkie Stinchcombe
James Tuer
Adam Winnik

Sabrina: Have you ever had to take out the garbage, kinda gross right? But someone's gotta do it, and we're not the only things that make waste; trees drop their leaves and animal's drop - well- other stuff. So what happens to all that waste that's created in nature?

(0:26) It turns out that waste, as gross as it may seem, is actually a good source of energy for lots of different living things like, bacteria, some fungi, insects, and worms. These organisms, called decomposers, break down waste and the remains of dead plants and animals to get their energy. Which is a bonus for the rest of us because thanks to decomposers there's a lot less waste and dead stuff lying around.

Now if you've been paying attention so far in our little talks here, you'll remember that all living things need energy to survive and energy flows through a system of living things moving from plant, to animal, to other animals in a "what eats what" model called a food chain.

We use  food chains to see how energy flows between living things in an ecosystem. So decomposers are living things too and since they need energy to live just like anybody else, they need a spot in the food chain. But where do decomposers fit in a food chain? Let's take a look at a simple little ecosystem to see where they might find a home.

(1:21) Plants, like this apple tree, are able to grab the energy that comes from the sun. They use this energy to take water, nutrients, and a little bit of gas from the air, to create chemical energy.

The tree stashes some of that energy in it's fruit, which happens to be delicious. If an apple happens to fall to the ground and gets nibbled on by a mouse, some of the energy from the apple is going to be transferred to the mouse. And if the mouse is unfortunate enough to be spotted by an owl, it's going to end up as an owl brunch, and the energy from the mouse will be transferred to the owl.

Apple, mouse, owl, that's a simple enough food chain right. Everyone has their place in it -  the system works. But decomposers can live and work in more than one spot in this food chain. They can show up any time there is waste to break down like the left over apple the mouse didn't eat or the owl's droppings. 

Decomposers break those things down into smaller parts into nutrients and other chemicals. These chemicals go into the ground and are taken up by plants so they can use them to make more energy, and the process starts all over again.

Not to get all Lion King on you, but I'm thinking this really closes up the circle of life, right? And since we're talking about circles and cycles, lets recycle some of these ideas one last time.


(2.32) Decomposers break down waste in an ecosystem into nutrients, and plants use those nutrients to make energy and that energy goes up the food chain all over again. And like I mentioned before, decomposers don't just put energy back into the food chain, they also keep waste from piling up in an ecosystem.

So while we might kinda of forget that insects or worms or fungi are there, remember that we need them to clean up waste. Losing the decomposers in the food chain would completely mess up the nice balance that all living things have going on. Which, okay yes, I guess means I'll finally clean up my desk! Until next time!