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Matter and energy in food webs

Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem. Created by Khan Academy.

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  • starky ultimate style avatar for user Alessandro V. Santoro
    Wait... Plants release heat?
    (12 votes)
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  • leafers ultimate style avatar for user S F
    why do humans consume so much?
    (8 votes)
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    • starky ultimate style avatar for user ®oman
      This is long but it's a loaded topic.
      A basic example (which is not what you asked I know but I'm getting there) of society's over-consumption is plastic, cellophane, etc. Which you may wonder what this has to do with consumption. Let me break it down:
      When the industrial age began it brought along with it the mass (or large scale anyway) production of foods. At first, this was generally canned goods, breads, flours, sugar, etc. etc. All good right? Well maybe at first.
      Preservative methods have been around for ages, whether it be the canning of fruits and vegetables or salting meat, it's nothing new for sure.
      But as the industrial food industry grew, longer shelf life would begin to need increasing and now we need larger fields for crops, so pesticides come into play. I'm not even gonna talk about what that along with the hormones they use in meat production does to your health.
      Most people probably love Doritos. Heck, I like them...Until you realize they literally use addictive additives (aka: MSG) which is why you can't hardly put a bag down. (does no one see this as a red flag??) Over-consumption at it's finest my friend.
      Where does all this tie in? What does almost everything you purchase come in? Plastic.
      Granted, there are people who go overboard, this is a real problem and it's where the main issue (aside from obvious health concerns) of over consumption.
      When the industrial age took off, growing your own food became an anomaly.
      Companies don't sell you food, they sell you a product.
      The plastic waste that comes from food packaging is over-consumption. We buy products, therefore we pay the price. I know you said general consumption but this is general consumerism. We as a people get so wrapped up in convenience we forget everything else.
      Like, I don't know, trees grow back and can be re-planted, paper disintegrates and plastic doesn't? Consumerism gets worse by the day and no one wants to talk about it.
      Drinks, hair products, cleaning supplies, these are all things that are okay but can be made so much better. This is consumerism, and why it's so high. This is the fatal flaw in the plan of convenience.
      (25 votes)
  • hopper cool style avatar for user Shams AlJaberi
    Are algae and bacteria producers? What about viruses? Is a rabbit a consumer because it eats a producer? The fox and rabbit are both consumers because they can't make their own food unlike producers, right? Decomposers make their own food by breaking down dead organisms. Does that include viruses? How do they make their own food? Or is a virus a consumer? Can somebody help me answer my questions please? Thank you. If somebody has some of my questions, can you upvote? That way I can know if I am the only one with these questions.
    (8 votes)
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  • leafers sapling style avatar for user Adam 2023
    Do rabbits hibernate?
    (6 votes)
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  • stelly blue style avatar for user Mirabel McGhee
    Is it possible for a plant to be a consumer? Aren't venus flytraps, for example, consumers because they consume flies and other insects?
    (5 votes)
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    • piceratops ultimate style avatar for user FrozenPhoenix45
      This is a great question, and honestly something that a lot of people miss. The answer to your question is no, Venus flytraps are not consumers, and here is why. (I may repeat some things that you already know, but bear with me, as I prefer to have a complete answer).

      Producers and consumers, as I'm sure you know, are defined by how they get their energy. Producers, or autotrophs, create their own energy through chemical reactions (such as photosynthesis), and consumers, or heterotrophs, get their energy from other organisms. Consumers cannot make their own energy, only have it transferred from organisms they consume.

      Why is this important? Because while plants such as Venus flytraps, pitcher plants, and sundews to capture and decompose insects, they do not use the insects for food. Venus flytraps are producers, because they create their energy through photosynthesis, just like any other plant. Since they are taking no energy from the insects and arachnids, they are not consuming them in the ecological sense, which mean they are not classified as consumers.

      Why do they trap bugs then? Venus flytraps (and other carnivorous plants) grow in very nutrient-poor soil, and they are adapted to survive in a harsh environment. They trap insects so they can break them down for those nutrients. For example, all plants need nitrogen to survive. Most plants absorb their nitrogen from the soil. Venus flytraps have low deposits of nitrogen in their environment, so in order to survive, their nitrogen must come from a separate source. Hence, the bugs.

      This is an important distinction. An organism is considered a producer if it creates its own food and energy, and it is considered a consumer if it must rely on other organisms for that. Since carnivorous plants can create their own energy and do not actually eat (in a biological sense) the bugs, they are producers. As far as I am aware, all plants are producers.

      Again, a great question. I hope this answer helps!
      (14 votes)
  • aqualine seed style avatar for user JazminR
    Huh- so poop can be reused-
    (5 votes)
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  • duskpin ultimate style avatar for user Lex
    foxes are omnivores.
    (6 votes)
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    • stelly green style avatar for user Lupa
      Yes, but the video shows the fox as a carnivore to simplify the food web. They consume rodents, marsupials, the occasional carrion, berries, and fruit as well as grains and certain types of grasses. However, their main diet consists mostly of meat.
      (3 votes)
  • leafers seedling style avatar for user John-Allan Reeve Potter
    but what if a animal(herbivore) doesn't have any natural predators?
    (4 votes)
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    • piceratops ultimate style avatar for user Chise Bugeer
      Will in that case, the animal your talking about has to die of old age, and then the body will be decomposed. Rhino's are the only herbivores with a few natrual predators because nobody wants to bother them, although humans are known to kill them.
      (3 votes)
  • starky sapling style avatar for user cool dood
    at first in the start of the vid it looks like toad from Mario is hiding off screen
    (4 votes)
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  • male robot hal style avatar for user QuantumUltimate
    This may seem like a dumb question but if all organisms in the end are made up of atoms, then technically the tree consumes atoms (water, co2 that kind of stuff), so it is a consumer just like the fox because it also consumes atoms. what is the difference if we are looking at things in a microscopic perspective?
    (3 votes)
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Video transcript

- [Narrator] In this video, we're gonna talk about food webs, which is really just a way of picturing how all of the matter, and how all of the energy flows inside of an ecosystem. Now, when I talk about matter, I'm talking about the atoms in an ecosystem, the molecules, when you look at your hand, it is made up of atoms. And it turns out that the matter is not created or destroyed, it's just recycled throughout an ecosystem. And we're going to see that in a second. And then when we talk about energy, it's the energy that your cells need to be alive, the energy you need to be alive, to not just exist, but to do things, to think, to move. And so this food web essentially describes that. As we've talked about in other videos, in most ecosystems, the great majority of the energy in an ecosystem comes from the sun. So what we have here is the sun produces energy. It travels to Earth, and then you have organisms, which we would call producers, that are able to take that light energy from the sun, and then take atoms and molecules from its environment, things like carbon dioxide in the air, things like water, and other nutrients. And it's able to construct itself using that energy from the sun. Now, when it constructs itself, it not only gives it structure, but it's also able to store energy. And right over here, we have several producers depicted. We have this tree here, which is able to do photosynthesis. We have the grass here that's able to do photosynthesis, and it's not just plants. You have things like algae, and other microorganisms that are able to be producers. But then we have things like this bunny, and this bunny is not able to harness energy from the sun by itself. In order for it to get its energy and its matter, it needs to eat one of these producers, probably some of this grass. And so we would call this bunny right over here, this rabbit, we would call it a consumer. And it is a consumer, you could think of it as both matter and energy. When it eats that plant, those atoms are then able to make up the bunny. It will poop out a little bit, so some of the matter might end up right over here. But then also there is energy that is stored in those molecules, and that rabbit can use that energy to exist and live, but as it does it, it does release some of the energy in the form of heat. And actually, even producers need to use energy in order to live. And as they do that, they also release heat. Now we have this fox, the fox is not a vegetarian. It does not eat, it does not eat trees. It likes to eat things like squirrels and bunnies, but big picture, it's not producing its own food. It's consuming food, so it also is a consumer. We can differentiate more in the future between things that eat plants, and things that eat other animals. And you can see in this food web, we draw an arrow from the thing that is being consumed to the thing that is doing the consuming. So a rabbit consumes a plant, and so the arrow goes from the plant to the rabbit. A fox consumes a rabbit or a squirrel, so an arrow goes from the rabbit or the squirrel to the fox. Now some of you might have noticed that we have these arrows that are pointing downward. And so let me scroll down a little bit. And we see these microorganisms, the worms, the fungi, the mushrooms right over here, and we call these decomposers. Now what decomposers are really doing is what what you would imagine, breaking down all of the things that might die, the poop that is falling down. And by doing that, it's continuing to recycle that matter. And when it decomposes, those atoms are released back into the soil, or the atmosphere, and then that can be reused by the producers. And once again, every organism in this food web is using some of the energy in order to exist, and do whatever it needs to do. And some of that energy is being released as heat in every single situation.