 Before Whitaker came up with the Five Kingdom classification system, things were very chaotic with some organisms. For example, unicellular eukaryotes like amoebas were placed with multicellular animals just because they didn't have any cell walls. And then there were some organisms that weren't given a place at all. One of them was Euglena, an organism that can photosynthesize like a plant and move like an animal. And because of this, nobody knew exactly where to put this organism at all. That is, until the Five Kingdom classification system. Whitaker's Five Kingdom classification system actually gave these animals, the amoebas and the euglenas, a home of their own. And that is Kingdom Protesta. Today, Kingdom Protesta is one of the most diverse kingdoms to ever exist. It contains all the unicellular eukaryotes and some simple multicellular eukaryotes as well. In this video, we're going to dive deep into protests and find out about the different types of organisms this kingdom houses. Now the members of protesta, they come with a variety of characteristics. For instance, some protests like algae, they can be unicellular or multicellular, mainly photosynthetic and almost all of them have cell walls. Other protests like protozoans right over here. These protozoans are always unicellular and they completely lack cell walls. Then there are some protests which look and behave like fungi, even though they're not actually fungi, like the slime balls right over here. And just when you think that you've seen it all, you'll notice that the multicellular protests have no tissue organization, meaning that the cells in these organisms are not organized into tissues. So you see what I mean? Diverse, different sets of characteristics for different groups of protests. Because of this, it's very difficult to have a strict set of common features for protests, like how we usually have for every other kingdom. Now let's talk about these groups of protests in a bit more detail. Generally, protests have been broadly classified into three different categories. There are plant-like protests, animal-like protests and fungus-like protests. Let's start with the plant-like ones first, a.k.a. all the algae. Like we talked about before, some algae are unicellular, like chlorella, chlamydomonas, all the different items, etc., etc. All of these algae are unicellular. And then there are some which are multicellular, like the seaweeds that you can find in the oceans. Some of the most common seaweeds that you might find are these, the kelps, which are a type of brown algae, by the way. Now algae are plant-like and not actual plants. So they only share a handful of characteristics with plants. For example, they are mostly photosynthetic and they have cell walls. But neither of them have the true body of a plant. The bodies of algae are not differentiated into leaves, stems or roots, like generally how you would see in a normal plant. Besides algae, euclina is also a plant-like protest. But euclina has the best of both worlds. It can behave like a plant and an animal, which brings us to our second category or the next category, which is animal-like protests, a.k.a. the protozoans. This includes all the amoebas, then this paramecium right over here, then there's also the Millarial Parasite Plasmodium, which is also a protozoan, and a bunch of different other organisms as well. Now these protozoans, they are exclusively unicellular and they also share certain characteristics with animals. For example, they lack cell walls, they are heterotrophic in nature and they need to digest their food just like us animals. Now they don't have fancy digestive systems like we do, but they do have something called a digestive vacuole or a food vacuole. Actually you can see some over here, let's take a closer look at this. Let's pick a different color for this. Okay, so do you see the grooves right over here? This is one, there's this one here, one more here. So these are the food vacuoles or the digestive vacuoles. And these organelles are designed specifically to break down food with the help of enzymes. Okay, so we're done with two of these categories, right? We did plant-like protests and we did animal-like protests. And I have saved up the most weird one for the last. And those are the fungus-like protests. That superficially look and behave like fungi, except they're not really fungi. Example, slime moles, which are probably the weirdest organisms that I've ever read about. Like most fungi, fungus-like protests like slime moles, which are these random blobs of organisms just lying, chilling there on decaying logs, are saprophytic in nature. So they are saprophytic in nature, which means that they get their nutrition from dead and decaying organic matter. So these protests, they secrete enzymes into the environment that break down the organic matter and release the nutrients. Then these guys, these protests, they go ahead and absorb all of those released nutrients. These organisms, the AK, the fungi-like protests, they also reproduce kind of like how fungi do. That is through spores. So these are different spores and they form these spores to reproduce exactly like how fungi do. But again, they're fungus-like, which means that they only share a few similarities with the actual fungi. And a big, huge difference between these two organisms, between these fungus-like protests and the actual fungi, is the presence of chitin. Fungi have chitin in their cell walls, but these protests, they don't. All in all, kingdom protesta is pretty crazy in a way. So crazy that many scientists today have found more advanced way of classifying these protests. And why wouldn't they? These organisms have been confusing scientists for decades about their origin and their characteristics. Maybe that's why I find this kingdom to be the most fascinating, the most intriguing of all the other kingdoms that have been discovered so far.