 Then a unicellular organism undergoes cell division or basically fission. We get more cells and as a result we get brand new individual unicellular organisms and therefore this is a method of reproduction for them. However, in multicellular organisms cell division just gives us more cells. We don't get brand new individuals and therefore this will not work as a reproduction method for multicellular organisms. And therefore in this video we are going to focus on the reproductive methods for multicellular organisms. Specifically we are going to focus on these three budding, fragmentation and spore formation. In the next video we will talk about vegetative propagation in great detail and if you are wondering in a previous video we have talked about fission, we have talked about binary and multiple fission in the previous video. So you can feel free to go and watch that if you missed that. Anyways, so let's talk about these three and we are going to start with budding. So what's budding? Let's take an example to understand this. Take an example of a sea creature called Hydra. This is what it looks like under a microscope. Let me make a drawing of that. Here it is. When this sea creature, Hydra, which is a multicellular organism, once it starts Once it is mature, that is it's ready for reproduction, what we will see is a tiny outgrowth from a particular part of its body. This outgrowth is what we call a bud. This process is called budding. As time passes by we see that the bud starts growing into a tiny new baby Hydra. Again, here's a picture to show you that. Here's an actual picture under microscope. You can see a new baby Hydra growing over here as a bud. Again, let me get rid of that. And then eventually this keeps on growing and growing. And once it becomes big enough, it gets detached from the parent body. And finally, we now have a brand new Hydra. So this is how budding happens. Now an important thing to note is as this baby Hydra grows, we will see it's going to look exactly the same as its father or its mother. Now because there are no fathers or mothers here, there is no gender over here, we're just going to call it his parent. So the offspring is going to look exactly like the parent. Why is that? Because this is an asexual reproduction. There is no DNA mixing like in sexual reproduction since the DNA is going to be exactly the same. We will see this will be identical to this. Now remember because this is an asexual reproduction, that means the offspring is going to look exactly the same as its father or mother, no we're just going to call it as parent because there is no gender over here. So in asexual reproduction, the offsprings look like clones of their parents. Remember that. Anyways, some unicellular organisms can also undergo budding. Let me show you that. Let me just make this a little small. Alright, okay. So if you take the example of yeast, then you see yeast also when it matures and it's ready to reproduce, it grows a small bud and then that bud separates out and you get a new individual. Now when I first learned this, I thought, hey, isn't budding the same thing as fission? Even in fission, cell division is happening. This looks like cell division, right? Well, there's a big difference. You see, when cell division happens, when fission happens, one cell splits into two new offsprings. Alright, but over here, that's not happening. You see a new offspring is growing from the parent and then it separates out. So this is the original parent itself and this is the offspring. But if this was fission, when fission happens, then that original cell itself divides into two new offsprings and that original parent is no longer there. Okay, does that make sense? So there's a difference between budding and fission. This now brings us to the next type of reproduction called fragmentation. What's that? Well, again, let's take an example. Let's, this time, take the example of spirogera. Spirogera is basically a green algae. It looks somewhat like this again under a microscope. And again, if I take a drawing of this, when spirogera matures and it's ready to reproduce, you know what happens to it? It basically just splits into many pieces and that's the reason it's called fragmentation. Basically, spirogela splits into many fragments. And then, and then each of this fragment starts growing the rest of its body. And that is the cool thing about spirogera. It starts growing the rest of its body. And as a result, we now see three, in this example, three new spirogeras. Well, I think that's the prurer for that. Okay, anyways, you have three new offsprings, three new individuals from one. That's the idea behind fragmentation. And by the way, this process of re-growing your entire body or re-growing parts of the body, this process is often called regeneration because you're regenerating parts of your body. And so in this type of reproduction, when the organism matures, they just fragment themselves into tiny pieces, and then the each piece regenerates to grow its entire body. So are there any other wonderful creatures that can do the same thing? The answer is yes. Let me give you some more examples. Let me make space for them. Okay, another famous example, which can do this, is planaria. It's a type of flatworm. Again, when planaria matures, it just sheds off its tail, this part. And then the two halves grow, regenerate the rest of their body, and then now you have two planaria. Another famous example is starfish. Even that can undergo this kind of asexual reproduction. Again, when it matures, it'll just get rid of one of its arms. And then this original starfish will regrow the arm, and that arm will start regrowing the entire starfish. And that's how we now have a new offspring. Now another cool thing about this is, even if the organisms didn't fragment all by themselves, but if some external forces chopped them into pieces, let's say for example, we humans go and chop them into tiny, tiny pieces, even in that case, we will find that each piece will regenerate and grow individual bodies. And it turns out some Australian fishermen discovered this the hard way. Turns out that their local water bodies were infested with starfishes. So they decided to just take some individual starfish and chop it off and throw it back into the ocean. They thought they had killed it. Turns out no, you can guess what happened next. Each of those pieces started regrowing, regenerating, and the population of the starfish exploded. So even if you chop them into tiny pieces, they can still regenerate. Now one thing to remember over here is, even though some organisms can regenerate, that's not their preferred method of reproduction. For example, even in the case of Hydra, if you chop them up, then each piece can regenerate into new individuals. However, Hydra doesn't do that all by itself. And it's for that reason, we won't say that Hydra reproduces by regeneration or this particular method of fragmentation and regeneration. The second thing to remember is that regeneration itself cannot be termed as reproduction. And here's the reason why. In some cases, like let's say a lizard, now if you chop off its tail, let's say if the tail comes off, then this lizard can regenerate a new tail. So this is regeneration. But this tail cannot regenerate the entire body. So in this case, regeneration is happening, but this is not reproduction. We're not getting new individual over here. So in general, we will not say regeneration is the same thing as reproduction. We will say if animals or organisms prefer to fragment themselves or all by themselves when they mature, and then if each one can regenerate into new individual beings, only then we will say it's reproduction. Lastly, this brings us to spore formation. The famous example for this is a fungus called bread mold. Again, we're looking at it under the microscope over here. And you might know about this. If you take a piece of bread and you just leave it outside, and if it's moist, you see a lot of fungus growing on that. Well, that's basically this bread mold. Again, let me make a drawing of this. So here's what a bread mold would look like if you zoom in and look under a microscope. And the technical name for this is called the rhizopus. It's a little weird name. And the way I like to remember this is I see this rising part over here. And I think of this as the pus part, even though it's not. So rhizopus, rhizopus helps me remember what the technical name is. Okay, but let me just tell you what's the actual name of these things. This rising part is called the hyphae. Okay, you may have to remember this for your exams. This is called the hyphae. And this top part, this hyphae, by the way, is not the reproductive part, okay? The top part, this blob-like structure that you can see over here, that part is the reproductive part and it's called sporangia. Sporangia. These are the only two names, labels that you need to remember over here. And sporangia, as you can see, these dotted things contain these dotted things are called spores, okay? Spores are kind of like seeds that they have the ability to grow into new rhizopus, new bread mold, but they're not seeds. We call them as spores. They have very thick walls to protect them. And so when this bread mold matures, this sporangia will just release those spores into the air and then when the spores find a moist surface, the bread needs, this fungus needs a moist surface to grow, okay? So when these spores find a moist surface, they will regrow, they will grow into new bread molds and that's how reproduction happens over here. This is basically why moist bread will grow fungus very fast. So that's pretty much it. So to quickly summarize, in budding, what happens? Well, we have an outgrowth with this called a bud that bud starts growing into a new individual and eventually when it's big enough, it splits from its parent and we have now a new offspring. In fragmentation, the organisms just fragment themselves and then each fragment grows into a new part and this process is called regeneration. And even if they get chopped up externally, artificially by some environmental means, even those fragments can still regrow. But remember, not all regeneration is the same thing as reproduction, as we saw in the example of the lizard. And finally, in spore formation, the famous example of bread mold, what happens is when this thing matures, lots of spores are released into the air and when the spores get a moist surface, each of them can start growing into a new bread mold.