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The Flow of Energy Through Plants and Animals
The energy flow through living organisms starts with sunlight and photosynthesis, then travels through the food chain in bite sized chunks.  Primary producers, primary consumers, secondary consumers, and decomposers are all part of the food chain. 
It's great to be an Omnivore.
Science and technology education from FT Exploring.
  Photosynthesis, Energy, and Life - Page 2  
   1. Photosynthesis Intro Page   7. Photosynthesis Links
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   2. Energy Flow in Living Organisms   8. Energy Changes  
   3. Photosynthesis Basics
 3b.Photosynthesis in a Leaf  
  9. The Mysterious Everything  
   4. Energy Pyramids  10. How Many Types of Energy  
   5. Which Plants Use CO2?  11. Cellular Respirations Links  
   6. Food Chains & Food Web Links  
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  Gorgeous sun shining on the Arizona desert      Except for a few exceptions, all of the energy for all life and human technology comes from the SUN.  
     Animals and humans can't eat sunshine.  Plants are the first level in the food chain.  They convert sunlight to food for animals (though the plants may not look at it that way).

The Mysterious Everything Keeps on Flowing
        The Mysterious Everything flows in bite sized chunks (literally) through life, from one living thing to another living thing to another Coyote over freshly killed rabit. living thing, and so on and so on, but not forever.  ("Energy's One Way Trip").  Matter also flows through life, but in this section we are only talking about energy.
     This flow of energy is transported through the animals by a system biologists call the food chain.  A food chain in a given ecosystem is usually very complicated but it is useful to think of the food chain in the four simple steps or levels described below.

     The drawing below only shows three steps. Which one is missing?
        Scroll down to read about the 4 food chain steps...


Energy's One Way Trip
     The flow of energy through life is not an endless cycle.  The energy doesn't go round and round getting used over and over again and never wearing out.  Its passage through the food chain can better be described as in and out.
     As energy moves up the food chain there is less and less of it to go around.  That's the main reason there aren't very many big fierce predators compared to the herbivores. Not enough energy for them!   We'll talk about this in detail in another section, but a brief explanation goes something like the following:
      Most of the solar energy that falls on the earth is not used by plants. It bounces back to space or heats the air, oceans, and ground, and makes weather, among other things.
     The plants only get a little bit of the solar energy that hits the earth.
     The herbivores only get a little bit of the energy that hits the plants.
     The carnivores and decomposers only get a little bit of the energy that was eaten by the herbivores.
     (Most of the plant energy that is consumed by a herbivore is used by that herbivore to keep itself eating, breathing, walking, and staying warm. Only a little bit is left over for the carnivore or decomposer that eats the herbivore.)
     At the end of the chain there isn't much of that original solar energy left.  
     We need fresh sunshine everday and new plants have to keep growing.  Otherwise the whole amazing system would quickly run out of energy and everything alive would come to a "dead" stop.
Energy flows through the food chain.
    Energy above flows (or jumps in bites?) from sun to primary producers (plant) to primary consumers (mouse) to secondary consumers (coyote) to decomposers (bacteria, etc.)

Picture of a Food Chain
     Energy flows from the sun to the plants to the plant eaters to the meat eaters. Energy flows from the sun to plants to herbivores to carnivores
1)  Primary Producers --  Green plants and certain types of bacteria and Green Plants are primary producers algae are the primary producers because they are the ones that produce usable energy for the rest of the living organisms on earth. They use energy from the sun to make sucrose, glucose, and other compounds that other life forms can eat and "burn" for energy.  In each one of those sugar molecules a little bit of the sun's energy is stored in a form that we can call chemical energy. But it might better be called "potential energy" since it is a sort of "doing-nothing-for-now-waiting-to-happen" kind of energy (for more on this visit Energy Changes).
Herbivores like this giraffe get there energy from the plants they eat
2)  Herbivores -  Herbivores are the plant eaters.  They have the ability to digest the plants they eat and release the energy stored in the plant cells for their own use. Some examples of animals in this group are deer, cows, elephants, rabbits, elks, zebras, most insects, and birds that eat fruit and seeds. Sometimes scientists call this level of the food chain the Primary Consumers (sounds like Economics class).

Carnivores - These guys are the meat eaters.  Predators and scavengers are in this group.  Sometimes this level in the food chain isFace of the Tiger refered to as the Secondary Consumers.  They eat the guys that eat the plants and sometimes they eat each other. Most of these animals can't eat plants at all.  They would starve to death if it weren't for the Herbivores digesting the plants first.   They've got the glamour job but they're really pretty helpless without all the boring plants and herbivores.
     Cats and dogs, killer whales, sharks, spiders, snakes, wolves, vultures, hawks, eagles, crocodiles, and many other fierce predators that for some reason we are especially fascinated with, are in this group.

4)  Decomposers - These are not the guys that sit around unwriting songsEarthworms are considered one of the decomposers. and symphonies (get it? The opposite of composers?).  They are the guys that eat up dead bodies - both plant and animal.  And aren't we glad they do.  This group of useful critters are mostly bacteria and fungus, but also, according to our sources, includes maggots, dung beetles, earth worms, sow bugs (shown below), and many other eaters of dead organic matter.  Without them there would be a lot of dead bodies lying around.
     They're like carnivores and herbivores, because they also have to get their energy from the cells of animals or plants. The difference is they prefer their food dead - very dead.
     What do you think?  Are maggots decomposers or carnivores (or just yucky little things we'd rather not think about)?
hamburgers are for omnivores Hamburgers are for Omnivores
     Some animals can eat plants and other animals.  So you could say they are both a herbivore and a carnivore.  That's the way humans are.  We can eat plants and we can eat meat.  La tee da.
      It must have been too difficult for biologists to say herbicarnivore or carniherbivore, so they decided to call humans, and others like us, omnivores.  It means we'll eat just about anything we can get our amazing opposable thumbed hands on.  
     Black bears and brown bears are in our omnivorous club. And pigs we think.  Can you think of any others?
     I can't think of anything better than being an omnivore.   We can be either primary or secondary consumers.    It's so empowering!

       Its been estimated that one large maple tree, with 500 pounds of leaves (fun raking in the fall), can make two tons of simple carbohydrates (sugar) during one nice sunny day!
    How many tons would that be in a month of sunny days?
Thank a Plant Everyday
       It starts with the sun.  The Mysterious Everything, that makes everything happen on Earth, flows continuously from the sun to the earth.
     All life needs energy to live, and the energy we need comes from the sun.  Unfortunately, we crawlers, slitherers, walkers, and flyers, can't get nourishment from the sun without some help.  
     We can stand in the sun all day, get warmed by it, even get a good sunburn, but we won't get nourished.
     What do green plants, blue-green algae, and a few types of bacteria, have in common?
    They are the only organisms that can turn sunlight into the little energy storage packages that we call sugar.  If it wasn't for them the rest of us would go hungry because we can't live without those little sugar molecules that only they can provide.
     Do plants seem a little boring? Sitting in one spot all day long, growing ever so slowly. Like watching grass grow, they say.
     Well they aren't moving fast, but they are busy. When the sun is shining, they're doing photosynthesis, furiously turning sunlight into stored energy that all the non-plants need for survival.  Every day they turn the sun's energy into millions of tons of sugar.
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  "Energy, energy, everywhere, nor any drop to eat". (with apologies to Samuel Coleridge).
    Our mostly stationary green friends come to the rescue.  They take a little sunshine from the sky, a little carbon dioxide from the air around them, a little water from the surroundings, and they turn those basic ingredients into little parts of themselves that we call plant cells.  This process is called photosynthesis.  (They also make and release a useful little gas called oxygen during photosynthesis.)  
    Each one of those plant cells contain little packets, or molecules, of stored energy that we call carbohydrates.  
Some of the most important and simple types of carbohydrates are called sugars.  One of the most important sugars for animals and humans is glucose.
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  Written by David Watson  
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