2.02 Energy Required

mountainside picture with a steep trail heading towards the top

Did you get enough to eat? I hope so! Take a look at the path we'll be taking up the mountain! This is some pretty rough terrain.

It will be a challenge don't you think? Make sure that you have plenty of food and water in your backpack. Even though we just ate a good meal, we are going to need lots of energy as we climb Trophic Mountain. We'll stop now and then to refuel as we climb!

As you know, it takes lots of energy to climb, or to do any kind of athletic activity, but did you know that it also takes energy to eat, digest our food, breathe, and it even requires energy for our hearts to pump our blood. Just like a flashlight will not work without batteries, organisms will not live very long without energy. While we're trekking up this slope, let's take a closer look at how living things get their energy.

How Do You Get Your Energy?

Living organisms can be sorted into two groups based on the way they get their energy: autotrophs and heterotrophs.

Plants are autotrophs. Autotrophs are living things that can convert energy directly from the sun, or in some cases, use environmental chemicals to make energy for their bodily processes. The sun's energy is converted to a usable form through a special process called photosynthesis.

Plants, algae and some bacteria are autotrophs. Autotrophs are also called producers, since they bring new energy to the ecosystem and provide energy for other organisms that eat the producers.

The word photosynthesis has two parts that might help you remember the meaning.

Photo means light.

Synthesis means to put together.

So together it means to produce using light.

Heterotrophs are organisms that must eat or consume other organisms, plants, animals, or both, to get their energy. Humans, birds, fish, deer, ducks, rabbits, and spiders are all examples of heterotrophs.

We also call these organisms consumers because they consume other organisms for their energy.

To a Higher Level

Go get a snack - replenish that energy supply! Stretch a bit and get ready to climb a little higher!

Here are a few more ways to to group the herterotrophs. As with the other groupings, it is all about what you eat - we call these trophic levels. In the very basic scheme you just learned, producers are on the bottom trophic level and consumers are on the top, but within the heterotroph group there are more levels. Take a look at these levels below (click on the term to see an example, with the definition).

Heterotrophs

Do you like mushrooms on your pizza? Mushrooms and bacteria belong to a special group of heterotrophs called decomposers. They absorb nutrients and energy from dead, decaying organisms. These heterotrophs perform a very valuable service. Think about it. If no organisms consumed the dead stuff, our world would be a mess! In addition, some of the nutrients from the dead organisms are returned to the ecosystem for reuse.

First Stop!

We've made it to our first stop, Trophic Peak Visitor Center. The rangers here have prepared a short, but special, video for you. It should help pull all these new ideas about energy together and introduce a few ideas we'll get to later in the hike. Take a break, watch, and listen carefully for the terms and ideas you've learned as you climbed this mountain.

The producers (autotrophs) bring the energy into the ecosystem as a part of their niche (their job) and they use some of the energy to run and build their bodies. The consumers (heterotrophs) must eat plants, animals, or both to get their energy. Special heterotrophs called decomposers recycle the elements and nutrients in dead organisms back into the earth to be used again.

images © clipart.com 2006 with the exception of, bear eating salmon © U.S. Fish and Wildlife Service 2006, notebook © Paul Anderson 2006