0:05 Good evening my dear students. Hello to each and every one of you. This is Dr. Anisha from Sri Chaitananya Educational Institutions. Welcome you all for our another session of zoolology class for NE 2025 bridge course for the aspirants of NE 2027. So here we are again we are here for the another class of zoolology in which we are going to learn few of the topics which will be helpful for us in studying the actual topics in our classes. All right. So here we are again. Yes. Namaste. Namaste and good evening to each and every one of you. So what are we have studied till now? We have studied till now about the various topics. Now we have started another topic that is animal kingdom. And in
0:52 this topic of animal kingdom, we are starting with the very basics of the animal kingdom. That is the basis of classification. The layers of the classification, the basis of classification, the characteristics based on which we call an organism to be an animal. So that is how we are studying right now. We have discussed about the level of organization that is cellular, organ, tissue, organ system level of organization. Yesterday, we have studied about the body symmetry. Now, here we are going further about the body plan, germ layers, body cavity and the segmentation. In today's class, so let's start here again. I hope you all have a very good
1:38 time right now and you all are enjoying the class with us. So that is why we are making an effort in making or in fulfilling your request or your achievements. So now here we are in the animal kingdom. Basis of classification what all we have studied yesterday basis of classification is the level of organization and body symmetry. We have discussed about the level of organization and body symmetry. So now what is it today? Today for the basis of classification we are going to study about the body plan. Okay. So we will be discussing about the body plan. Today we will be discussing about the germ
2:23 layers. We will be discussing about the body cavity or cylom segmentation. We are going to study these together. First we are starting with the body plan. Since we know the body is either made up of cells or tissues or organ or organ system they have a symmetry. They have a plan. They have an arrangement for the places of different organs. Every organ has a different place. Every organ has a different location and that is the body plan. How is it planned? That is the body plan. So now here it is body form or the body plan. Body plan basically can be divided
3:12 into two types. Now what are these two types of the body plan or we are calling it as the body form. Body form or the body plan is of two types. These two types are first it is the tube within tube body plan tube within tube body plan and another is the blind sack body plan tube within tube body plan and blind sack body plan. There is one more body plan which is called as the cell aggregate plan which is the most
3:58 primitive type of the body plan. So cell aggregate blind sack tube within tube body plan. These are the three different types of the body plans we have. What is this cell aggregate plan? Now since we have seen pipera is made up completely of the cells various types of cells are performing the function of the digestion, respiration, circulation, excretion everything all the functions are performed only by the cells themselves. So that is the body plan which are called as cell aggregate plan. So cell aggregate plan is the body plan commonly seen in the periphereral. They are the most primitive type of body plan and there is nothing much planned
4:45 in it because all the functions are performed by the individual cells. So cells or the aggregates of cells are performing the functions of different body structures. So that is called as the cell aggregate body plan. Cell aggregate body plan is first of all they are present in periphereral and all these cells performing functions all these cells performing various vital functions are called as the cell aggregate body plant. Since the cells are forming or cells are performing different functions it is cell aggregate body plant. Now we are coming to these two type of body plan which are very
5:31 important called as the blind sack and tube within tube body plan. So now what is blind sack body plan. Blind sack. So what is this blind sack? See here in this diagram also we can see this is the blind sack body plan. Here we have seen that there is a single opening for entry of the substances and again through this pathway only there is exit of the substances. So there is only single opening which is acting as through the for the process of injection as well as ejection. So it is like a sack a single sack with a single opening almost like imagine a purse or a bag. If
6:18 you have a bag, there is only one opening through which we put the things inside and we take the things outside. So there is only one opening which is helping in the process of injection as well as ejection. So such type of body plan in which there is only single opening only single opening present and this single opening helping in the process of injection and ejection both. So it is like a sack. It is like a bag with a single opening through which all the things are going in and the excretory material or the other excretory material or the poisonous material is coming out through that
7:03 single opening. So such type of body plan is called as blind sack body plan only single opening present which helps in which helps in both injection. What is the meaning of injection? I hope you all know. Injection means intake of the food. Injection or intake of food. So injection and ejection. Eas means the release of toxic material. Release of toxic material that is the ejection. So through a single opening both injection and ejection is being performed. Such type of body plan is called as blind
7:48 sack body plan. And what all pylum are included as blind sack body plan. Pipera already segregated as the cell aggregate plan. So what will be there? Again if we remember the sequence pipera followed by celintraa topora platy helman sashkalus sanida arthropod. Yes, a number of them are there. But what will be included in the blind sack body plan? Cylinda, tenophora. Yes, even platty helmets, they also have the blind sack body plan. So, cylinder, cylinder,
8:35 tenophora, and the flat worms. They have the blind sack body plan. So they have only single opening for both injection and ejection. They do not have a separate opening for the process of excretion. One opening for both injection and ejection. So here is this it is like a closed sack with a single opening. Now we are coming to the part which is called as the tube within tube body plan. So what is this tube within tube body plan? See here there is one single tube within the whole body tube. Imagine the whole body a single tube.
9:20 Inside the body for example human body inside the body there is oral cavity, esophagus, stomach, intestine and rectum. The whole of the digestive tube is there. So inside the human body there is the digestive tube another tube tube within a tube. So tube first tube is the digestive tube or we can call as the elementary canal or digestive tract that is present within another tube which is the body cavity or the body tube. So tube within tube has two separate openings. one opening here for the process of injection. Another opening here for the process of ejection. So two
10:07 separate openings for injection and ejection is called as the process or the body plan of tube within tube body plan. Okay. So tube within tube body plan very sim very simple blind sack body plan has single opening which is acting both as the mouth and anus both for injection and ejection tube within tube there are two separate openings one is acting as the mouth another is acting as the anus. So tube within tube why the name given tube within tube if the whole body is a tube within it or inside it another digestive tube is present. So that is tube within tube. So here we are now it
10:52 is the tube within tube body plan. So tube within tube body plan in which there are tube present which is the digestive tube. Two separate openings. Two separate openings for injection and ejection. Injection and ejection. one acting as one acting as the mouth and another is
11:37 anus. Another is anus. So you all are writing it down. I hope because it is important you need these things for your future classes. So make a note of it, write it down, remember it, go through it various times, revise it repeatedly so that you remember these terminologies. So this is called as tube within tube body plant in which there are two separate openings for the process of injection and ejection. For the process of injection, there is the mouth present and for the process of ejection or excretion, there is anus present. Such type of body plan is called as tube within tube body plan. Now tube within tube body plan it is
12:22 present in which type of organisms? What all examples will be there for tube within tube body plan. What all it will be? Now we have seen pifera celgregate plant cylindrate tenophora and platyhelmus blind sack. Now it has evolved even more. Earlier only cells were acting as for the process of digestion and excretion altogether. Now it evolved into single opening for both injection and ejection in cylindrate tenopur and platel means. Now they have developed even further. They have two separate openings one as the mouth and the anus. So now they have most evolved organisms which is starting from the film ashkal minthus. So starting from
13:10 ashkal menthus anida arropoda molliska ikinodomea hemicordita and cordita they all have same type of body plan that is tube within tube body plan all right so that is why I have told you to memorize the sequence of the film starting from pipera then the cylindra tenophora flatty helmascales and every time I Repeat these sequences so that each time you hear them it repeats in your brain and you remember them. Okay. So now what all phylm will be included in this? Ashkalis, ana, arthropoda, molesca, ikinodmata, hemicorda and cordata. So
13:56 till cordata starting from ashkal minus till cordata they have tube within tube body plan. This is the most evolved body plan. All right. So this is about the body form or body plan cell aggregate blind sack tube within tube. All right and I hope you all have understood it. You all now remember it. So till now we have completed the level of organization body symmetry and body plan. Now moving on to the next part the germ layers. Now what are these germ layers? Okay. So what are these germ layers? What do you understand by germ layers? Germ layers means we have already discussed about
14:43 embryology. In embryology we have seen that zygote is there. Zygote under goes division. It gets divided into two cells first 2 to four cells. 4 to 8 8 to 16 these number of cells will be present. Now these divisions are done by which type of cell division? Yes. It is called as cleavage cell division. Now cleavage division divides the 2 to 4, 4 to 8, 8 to 16 cells stages. So from there we are coming into this germ layers. How the germ layers then getting formed? The formation of the germ layers. Now what is happening here in the germ layer formation? for the formation of the germ layer. Say if you have the zygote
15:29 divided into two cellled stage into four cellled stage which finally forming 8 to 16 cell stage or we can say mass of cells. So we have in the blastoyst condition mass of cells. So this is the structure containing mass of cells. After this stage the cells will rearrange themselves. How this rearrangement take place? The rearrangement takes place in such a way that some of these cells the outer layer of cells will arrange themselves in this layers. These layers are the outermost
16:15 layers. Some of these cells will arrange themselves in this inner layers like this. Okay. And rest of these cells will be present here in these forms in these forms like this. Okay. So these are the three layers. The outermost layer of these cells, the outermost layer of these cells, they are called as the ectoderm or ectodermal cells. The outermost layer is called as ectodorm. Ectodorm gives rise to various components like the nervous system, like the skin, hair,
17:02 nails, the epithelial surfaces. All of these are formed by the outer layer of cells called as the ectodum. And the digestive tube, the digestive tube or the inner tube. The digestive tube or the inner tube is formed by the digestive tube or the inner tube is formed by a group of cells. The layer which is called as endodm. So the outer layer of cells they have ectodom and inner layer of cells they are called as the endodm. Most of the organisms or some of the organisms have only two gem layers ectodom and endodm. They have not evolved to form
17:49 the third germ layer. The outer ectodorm and inner endodm are the only two germ layers in many of the organisms. These organisms which have only two germ layers are called as diploastic organism. Blast means the germ cells. So diploastic two layers of the germ cells. Another is the organism in which outer ectodorm is present, inner endodm is present and in between misodorm is also present. Okay. So outer ectodorm, inner endodm, outer ectodorm is forming again the
18:34 layers which are forming the nervous system, the skin, hair, nails, the epithelial surfaces. The outer parts endodm forming the gastric tube or we can call it as the digestive tube and in between the various types of connective tissues the muscles bone cartilage blood lymph everything is formed by a third layer which is present in between them. The third layer which is present in between them. This third layer which is present between the outer ectodorm and inner endodm is called as the misodorm. So this misodm is not present in all the organisms. Organisms with three germ
19:20 layers are called as triploastic. Okay. So organism which has ectodorm and endodm as their germ layers are called as diploastic. And organisms with three germ layers ectodorm, endodm and in between there is the third germ layer misodorm is called as triplolastic. So now we are here again whom we call as the diploastic film and who all are triplloblastic film. So here we are again see diploastic organisms. So what is it diploastic organism? This is the outer ectodom. The outer ectodom. The inner endodm in both of them. The inner
20:06 endodm. In case of triploastic organism there is this cellular living layer of misodum present. Whereas in case of diploastic organism ectodorm endodm they have this middle layer inside which is not misodum. It may be some non-cellular layer. It may be some jelly- like secretions. It can be anything but it is not cellular living layer. It is not misodum. So they have ectodom and endodm only. They are the diploastic organism. What are the examples of diploastic organisms?
20:53 Diploastic organisms we can say cylindrates. Cylindrates are diplolastic. Tenopores they are diplolastic. So cylindrator and tenophora they are diplolastic organism. That means they have an outer ectodorm and inner endodm only in between whatever they have. It may be a sticky substance, jelly- like substance to keeping to keep the two layers together. But this is not cellular layer. This is definitely not going to be made up of misodum. So misodm is absent in between ectoine and endodm. some thick jelly- like substances present that is the phylm cylindrator and tenophora. Now
21:41 again we are coming back to the evolution again we are coming back to the sequence of the film which all will be included as the triploastic if cylindrate and tenophor including the piperence also if you take aside cylindra tenophora is already gone. Now we are starting with the platty helmets. So starting from the platty helmets and if we are going till the cordita it will again be the platty helmans and I hope you all have now remembered the sequences. I hope you all memorize the sequences. Now the platy helm means the ashkal meanthus after that ashkal meanthus anila arropoda molliska I'm not going to
22:27 write all of them because I know you all remember it analida arthropoda molesa iinoda hemicorda and again cordata so that is where the sequence plays the major role you need to remember which all will be included and at which point. So here we are again cylindrated tinophora they have the they have the diploastic layer they have diploastic layer of the germ layers and starting from platty helmans platty helman means ashkalis anolina arthropod molesa echinodermita hemicorda cordata they have triploastic germ layer all right everyone I hope now you have memorized
23:13 the sequence that is very very important And you all are so interested and you all are so focused. I'm very sure you must be doing very good in your studies right now. So this is about the germ layers we have discussed. Germ layer formation occurs from the embryionic stages. Various cells they arrange themselves in the different layers to form the ectoendo and misodum. Now what comes after the germ layer? Okay. So this is body cavity or cylom. Now the concept of body cavity and cylom is not very clearly written in your textbooks. But I'll tell you what exactly the cylum or body cavity is. Imagine this is the
24:00 human body. Now the human body has as this as the digestive tube. Okay? If this is the digestive tube. This is the digestive tube. So this is the digestive tube of the human body and rest part is the human body. Now the rest of the part rest of the part here there is rest of the part here this is an open or empty space present. This whole part it is the empty space. This empty space present between the body wall and the digestive tube is called as the cylum or body cavity. Okay. So now here
24:49 we are again. Yes, I know you might be little confused with what I have said. I'll explain it again. See here if this is the body wall and this is the digestive tube. Okay. So the space between them is empty. That space has many structures in it. But that space is called as cylom. That is column or body cavity. So now in human body we have understood what is cylom look like or how the cylum appears like. But how do we define it in any of the body? In any of the animal or in any of the organism whether they have a well- definfined digestive system or not
25:36 the body cavity will always be what will it be? The space between the body wall and the digestive tube. The space between body wall and digestive tube is called as cylom or body cavity. How do we define it? As a definition, the body wall space between body wall and digestive tube space within them. Space within them is the column. Okay. So, space within them is the clo. Space within them is column. Now,
26:21 how do we define it? When do we call this to be a cylum? A cylum is defined as with the help of their germ layers. Remember we have seen these structures. This is the ectodorm. If we take this is the endodm. If you take okay this is the ectodorm and endodm we have taken. Okay. This is ectodorm. This is endodorm. All right everyone we are going in detail about the cylum. What cylum is actually what cylum is made up of. So outer ectodorm and inner endodm. The empty space endodm encloses
27:08 the endodm is the digestive tube through which the food passes. So this is the hollow lumen. This is the hol lumen. All right. The esophagus, the stomach, the intestine. That is the hollow tube that is formed by the endodm. And this is the body wall that is the ectodom. Now the space between them ectodom and endodm the space between them is empty or we can say filled with fluid and many other components. The space between them first of all. Second the space should be completely lined by like this. The space should be completely lined by the third germ layer which is the misodum. So these
27:55 two things must be completed. First an empty space an empty space must be there must be present between ectodom and endodm. An empty space present or empty space should be there present between ectodorm and endodm. There should be an empty space between the body wall and the digestive tube. Similarly, the space should be empty between ecto and endodm. And second second thing is it should be completely lined by it should be
28:42 completely lined by misoderm. It should be completely lined by misoderm. So it should be completely layered with on both these sides the outer and the inner side it should completely be layered with the third germ layer misoderm only then it will be called as cylom or a cavity. A true or a body cavity will be called as a body cavity only if these two things are seen in them. one the empty space between ecto and endodm and second it should be completely covered with the
29:30 misodum. So these three germ layers together forms the body cavity. All right. So this is the basic structure of the cylum. Now we are coming to the part what are the different types of cylum. We have seen or we are going to see different organisms have different types of body cavity. I'm very sure this type of body cavity you have seen. All the other organisms do not have the same type of body cavity. They have a different type of body cavity. Now what type of body cavity is there? So three three possibilities are there. We are going to see three possibilities there.
30:18 All of these we are taking as the ectodom. Okay. Four rings we are here seeing. So these are the ectodorm and all of them have the endodm between them. So they all have endodm between them. So this is the endodm between them. All right. So they have endodm between them. So ectodomorm and endodm. Okay. All of you are following. All of these are the ectodomorm. These ones are endodorm. Now this first diagram, see this first diagram. In this first
31:04 diagram, there is no misodum present and some of the components are present here like this. Some tissues, some cellular, non-cellular structures, they are present like this. Okay, there is no misodum present. Now there is a third type of process here in which there is the presence of the misoderm like this which is filled with a tissue. Okay. These are the possibilities that we are going to see in actually some of the organisms. First has no misodum. Second has misodum. They have
31:55 misodum. And the space is filled with some of the components between ecto and endodm. Some of the structures are present. Some of the tissues are present. Now the third possibility. The third possibility is that there is misoderm is present. Definitely misodum is present but misodm is not complete here. Misodm is not complete here. Misodm like this present. Misodm is not complete here. Incomplete misodum is present. And the fourth one is there in which there is complete presence
32:43 of misodorm. So now what all these types of possibilities are saying? The first one in which only ectodorm and endodm is present. There is no misodom present. These are for the diploastic organism. No misodom is present only ecto and endodm is present. So such type of organisms in which no misodom is present then there is no possibility of any kind of cylum formation such type of organisms are asylum. They are called asylumate organisms. They are called as aselomate because they do not have
33:30 misodum present in between them. So first criteria which what all criteria we have seen there should be two criteria to be called as a complete clo one there should be an empty space between ecto and endodm and the layer should be the empty space should be completely covered with the completely covered with the misodm. Here there is no misodm. So that means no misod. Okay. Lassia is asking why there is no misodum. Because in case of germ layers, diploastic organisms we have just read diploastic organisms are made up of two germ layers. So in those organisms the diploastic organisms since they do not
34:15 have the third germ layer itself they are called asylumate. There is no misodum because of their developmental conditions because of their evolutionary primitive nature. They are not evolved like the tripoplastic. So that is why they contain only the two germ layers. Such type of organisms are asylum. So in one word we can say all the diploastic organisms are asylum because they do not have the gem layer. Third gem layer. So there is no question of cylum formation is coming. So aselomate organisms first type in which there is no misodum at all. Second possibility another very important see here. Now they have the
35:01 organisms they have the third germ layers. The misodm is present. Ectodorm is there. Endodm is also there. And misodum is also there. And in between ecto and endodm there is the thick tissue present. Since there is no empty space available. Ectodorm and endodm is completely filled with the space between them is completely filled with a tissue. It is a tissue of different function. It can be excretory. It can be of nutrative of different function. That is not the point. The point is ectom and entodm do not have an empty space present between them. In the first scenario misodum was
35:47 absent. In the second scenario the whole empty space itself is absent. Even if they contain the third gum layer misodum. So here they have misodum but the first and the ectoin endodm there is no empty space. So even they are also called aselomate. So the first and second type of scenario is of aselomate group. They are called aselomate organisms. Now who these aselomate organisms are? What are the examples of such a aselate organisms? So what all are asylum organisms in this case? Celindraa and
36:35 tenophora. These are asylum organisms. Celindraa and tenophora they do not have the third gem layer. They are diplolastic just now we have seen. So they are also a hyelomate and this is the case we see in case of platty helmets in which third germ layer is also present. Misodm is present but there is no empty space present between the ecto and endodm. Hence they are called asylumate. Empty space is not available. That space is covered or filled with a tissue. So they are called asylumate again. So we have two types of organisms both asylum. One group is they
37:23 do not contain misodum another group do not have the empty space. Now it is the third scenario in which there is empty space present between the ecto and endodm. There is misodorm also present but the misodum is not completely lining or completely covering the whole empty space. The empty space is not completely covered by misodum. They are present in the form of some pouches. Such organisms are called as sudoate. Such organisms are called as pseudoelomate. So they are pseudoylumate. Sudo means
38:09 the false false selom. They appear like the sylum but they are actually not sylum. Even they are also present in tripopolastic organism. They are also present in tripoplastic organism. Outer ecto and inner endodm is present. Misodm is also present in the empty space but they are not completely covering the misodorm. So empty space empty space not completely covered not completely covered by misodum. So misodermal pouches are present. Misodm in the form of pouches are present. These are misodum pouches.
38:57 So misodermal pouches are present in between the outer ecto and inner endodm. Such type of body cavity is called as p sudoate. Now which organism has pseudoylate type of body cavity? It is the round worms or we can call them ashkal minus. Again we are following the sequence. See here how they have evolved. Earlier there were no gum layer which is the misodum. In the next they appeared as the misodum but the space between them were not present. In the third misodum were not completely covering the empty space. And now here it is which is called as the fourth
39:44 scenario. The fourth scenario is called as ucelomate. Usillomate or also called as trueillo. true or ucelomate. Now what are these ucelomate or trueum organism? Usyelomate or trueum organism contains the ecto and endodm space between them is also present and the space is completely covered by misodm. So that is called as true. Now true selenomate organisms are present starting from the [Music] anila till cordata all the film they are
40:33 ucelomate. All right. So this is the point of formation of cylom. And I hope you all have understood it. Raise your hands or we can say give me a thumbs up. You all have understood what is sylum and body cavity formation. How the body cavity is formed, how they are different and what all we see in each and every film. Give me a thumbs up if you have understood. Like the video if you have understood. Okay. So this is asyomate. Asylumate both of them are asyomate as we have seen in case of the cylindra tenophora and platty helmets. Pseudoselomate it is the ashkal minus
41:18 true silomate it is the analida arropoda molesca echanoda hemicorda and cordata okay very good everyone I'm very happy that you all have understood and you have appreciated the effort thank you so much okay okay so now here we are we have cleared about the body cavity, germ layers, body form or the body plan. Let's go for some of the questions. Segmentation is there. We'll just discuss very little about the segmentation right now. What is segmentation? Segmentation means the
42:05 body will be divided internally and externally both. How the body is divided internally and externally? It is very shocking to understand that the bodies are actually segmented or divided. For example, if you take a earthworm or a leech, their body, if you take an earthworm, their body appears very clearly segmented. The segments are very clear in all of them. We can see they have this clear segmentation division throughout their body. But what about human body? Are they segmented? Yes, of course, human body is also segmented. Here we have taken an example of a fish. The body is divided into head, trunk and tail. Similarly, human
42:52 body is also divided into head, thorax, abdomen. So the body is divided. Head contains the brain. Thorax contains the lungs as well as the heart and other structures. Abdomen contains many structures, many organs, the digestive uh the reproductive system, urinary system, all of these. So they are segmented internally as well as externally. Same with the fishes, same with the amphibians, the reptiles or many other organisms. Same with an insect. The insect's body also, the insect's body also is divided into many segments. If you see here the insect body is divided into the head or the abdomen part the tail region. So it is divided into head
43:40 thorax abdomen in case of insects also. So in case of the analids the segmentation is a little different but it is also segmented. In case of arropoda again the body is also segmented. And in case of the film cordata the body also shows segmentation. So true segmentation is the one true segmentation is defined as when the body is divided into when the body is divided into many segments
44:26 both internally internally as well as externally both internally and externally that is called as the true segmentation. So for an organism to be called as truly segmented what we need to know for an organism to be called as truly segmented we need to know they are segmented internally or externally or not. If they are not segmented both internally and externally that is not true segmentation that is not segmented they are unsegmented. Which are fililem are truly segmented? These three filmm the film such as phylm
45:13 analida arropoda and cord data contain truly segmented organisms. Anila arropoda cord data contains truly segmented organisms. Okay. So this is about the different segmentations of the body. Few questions we have. Few questions we have which film shows the tissue level of organization. I'm very sure you all can answer these questions very easily. The first question film shows tissue level of organization. The protozoa, the pipera, the cylindrator. Which all will be your answer? The answer will
45:58 be yes. Yes. Who all are answering? Okay. Shiva joti is answering a puja protozoa tissue level of organization issata. All right, next question. Organ system level of organization. Yes, most of you have answered. C organ system level of organization. Organ system. Organ system level of organization is present in analida, arthropod, moleska and platty helmets. So organ system level of organization it has multiple answers which are correct. So if it is organ level it will be another different one
46:44 the organ system will be different. Organ system is present in analytica organ level of organization is present in laty helmets. All right. Next question. Incomplete digestive tract or blind sack body plan. Incomplete digestive tract or a blind sack body plan. Incomplete digestive tract or blind sack body plan. Blind sack body plan will be present in the organisms which are diploastic also. So this will be diploastic as well as the organisms will be the platty helmets. The members of the film porifera are commonly known as members
47:31 of the phylm porifera porifera filylm. It will be known as sponges. And this is the I think last question. Which of the following groups of animal is bilaterally symmetrical and triploblastic? Bilaterally symmetrical as well as triploblastic. Which of these? Ashkalus triploastic bilaterally symmetrical. Yes. Tenop force not triplastic sponges not cylinder not. So it is the first answer. So thank you everyone. Here we have completed till segmentation. Next class we will go further in details of the animal kingdom and various other aspects of classification and their
48:18 basis.
