what is the similarity between a butterfly a dolphin a jellyfish and a leech well they're all animals but they are so different right that means the animal kingdom is really really vast in fact the total number of animal species is estimated to be about 8.7 million that's a lot so how do we even begin to make sense of such a vast Kingdom of organisms and how do we classify them fortunately there are very simple criteria which helps us differentiate them into phyla so the animal kingdom has several phyla singular phylum and plural is phyla so in this video we will take an overview of all the phyla that are there under the animal kingdom and look at some very basic criteria that we use to differentiate between them now if you're not very familiar with how animals are classified you will come across the names of a lot of phyla which will be very new to you we'll come across many unfamiliar names don't worry about remembering the names just yet just try to understand the basic criteria that are used to classify animals into these different phyla and you will get these names once you go through other videos on each of these different phyla so one thing that is common between all animals and in fact all living organisms is that they're all made up of cells you must have studied that cells make up tissues which gather together to form an organ and organs gather together to form an organ system and several organ systems together form an organism so these are different levels of organization but there are some animals in fact the most basic of all animals only have cells they don't have the tissue or the higher levels of organization they are that simple that is the most primitive type of animals and they are the sponges so there are these animals some of them are really beautiful like this one that only have a cellular level of organization and they form the phylum peripheral peripheral because they have pores in their bodies that's why they are called sponges because sponges of pores right so these are the most primitive phylum of animals look carefully at this animal do you see any symmetry in their bodies in fact these animals are so primitive that there is no symmetry so what do I mean by symmetry take the human body so you can imagine a plane passing through the middle of the human body like this so here I've drawn a line but if you imagine three dimensionally it will be a plane that will divide the body into two equal halves so that is symmetry you can make a plane pass through the body of the organism which will divide it into two equal halves bilateral symmetry is a type of symmetry so this is bilateral symmetry in which there is only one plane that can divide the body into two equal halves there is another type of symmetry in which there are more than one planes that can divide the body in two equal halves like in this flower it's it's a type of symmetry that is present in animals as well as flowers so for example take a look at this flower can have this plane divided into exactly two equal halves then there is this plane that divides it into two equal halves similarly there are three more planes so there are five planes that divide this flower into two equal halves so this kind of symmetry where there are more than one planes which divide the flower or the organism into two equal halves is called radial symmetry so the most primitive type of animals the sponges as you saw they do not have any symmetry but the next most primitive animals they have some type of symmetry like our jellyfish over here so a jellyfish can be divided by many planes into two equal halves so the jellyfish belong to a phylum called but this is the current name naderia see silent and there is another phylum just above nideria which is made up of these marine animals they also have radial symmetry and this is called phylum tinophora again C is silent they are also called comb jellies again don't worry too much about the names if you're seeing them for the first time when you read in more details about these phyla you will become more familiar with the names now these animals not only have some symmetry they also have tissues remember the phylum peripheral the sponges they did not have any tissues all they had was cellular level of organization but these animals are a little more sophisticated their cells are organized into tissues and they had two layers of tissues when they were embryos so this is what they looked like this is called Diplo stick Diplo means to so there are two tissue layers in the embryo so I can see here three one two and three so what is the third thing we'll come to it in a bit first let's take a look at the two tissue layers the outer one is called the ectoderm Derm means skin Ecto means outer so it's the outer layer of the tissues and the inner layer is the endoderm Endo means inner now what is this white thing it's actually a space its position is innermost to all the tissue layers and that usually happens to be the gut the digestive tract of the animal now phyla nideria and tinophora are diploplastic but animals which are higher than them they are triploblasting like over here so this is triploblastic means these animals had three tissue layers when they were embryos so the blue one again it's the ectoderm the red one is the endoderm there's another tissue layer in the middle called the mesoderm meso means middle so ectoderm endoderm and mesoderma the three layers in triply plastic animals now in many textbooks and in videos you will find there is a layer that is shown even in diploplastic animals that is not a cellular layer okay there's something called the mesoglia that you'll find in some books that's formed by secretions by cells but it itself is not made of cells so that's not a tissue layer now animals which are a little more advanced than nidaria and tinophora are all triproblastic these animals are also bilaterally symmetrical plastic animals have a few varieties the first variety looks like this this is pretty much the same that you saw just now there are three layers ectoderm mesoderm endoderm than inside there's the gut so these animals the animals which have this type of arrangement of triple plastic tissue layers are called and why they are called so we will see in a bit so the phylum that comes under acelomates there's only one phylum like that and it's a platyhelminthes so this is phylum platy helminthes platy means flat and helminth means warm so they are also called flatworms and this example right here is a tapeworm so tapeworm belongs to flatworms or phylum platyhelmintis and are acilomates the next type of triploblastic animals have something else besides the ectoderm endoderm and the mesoderm so here we have the ectoderm here is the mesoderm the red one is the endoderm now what is this blue thing that is something extra these animals and this is a space now this space is not the same as the white one not like the gut it's a body cavity it's a cavity that is present between the tissue layers and that is important because it gives the body of the animal some firmness and some resistance to let's say you know blows so that it's not squished and it also is a place to hold internal organs and in these animals the body cavity is called a false ceilum why is it called a false film we will again see in a bit so this type of animals are called pseudo selomates because pseudo means false they have a false body cavity and the phylum that has the false ceilum is called phylum nematoda or ascalmintis the older name they're also called roundworms because they're kind of cylindrical and you might have seen many worms in your daily lives you can see them sometimes in vegetables or in soil and stuff many of them are also parasites like ascaris so these are the nematodes or ascalmintis so now I hope you understand why we were calling the previous types of animals as acelomates acelomate because they did not have any serum they did not have any body cavity that's why they were acelomates and these animals are pseudosealamates so you must be wondering if there are animals with true silum yes there are all the animals that are higher than these are true sealamates they have a true silum so ectodar mesoderm the red one is endoderm and the blue thing is the true silum so why do we call this the true silum and how is it different from the fall sealum so the true silum it is present between present Within the mesoderm so the orange one here it is the mesoderm and you see the blue thing the body cavity the true serum that is within the orange layer so that is true silum whereas in pseudosilomates body cavity was present outside the mesoderm so here you see there's the ectoderm the mesoderm then the body cavity and then the endoderm the body cavity is outside the mesoderm hence it is called the fall seleum another difference is in the false ceilum the fall sealum is fluid filled it's filled with a watery substance whereas the true silum it's it's actually a space like for example inside human bodies there is a space which holds all these organs the heart the stomach and everything else that is the true sealer so these animals are called celomates because they have the sealum so what falls under silomates well all the rest of the animals all the animals higher to the pseudosulamates are true silamates and there are quite a few of these phylum so first there is this phylum which has leeches this is a leech and then it also has earthworms and it's called analida phylum analida then there is the phylum with all the insects and spiders and scorpions and lobsters and prawns crabs this phylum is called arthro poda then there is the phylum with snails and oysters and octopuses and squids and this phylum called next is the one with starfishes and are called echino dermata there's this phylum with these warm-like creatures which are found under the sea and they are called hemichord data and finally we have the most evolved phylum of all which has the Dolphins the monkeys the birds the fish the crocodiles and us and is called phylum chordata so let's just quickly go through once again what we saw in this video so we start with the most primitive animals again they only have the cellular level of organization and are the phylum peripheral which has sponges in it then there are the diploblastic animals the ones which have only two tissue layers in their embryonic stage and include the jellyfishes philemonitaria and these comb jellies or phylum tinophora next there are the acelomates the ones which are triploblastic they have three tissue layers in their embryonic stage but no serum no body cavity and they include the platyhelminthes phylum the flatworms an example is the taper then there are the pseudosilomates which have a false celum and include the phylum nematoda or ascalminthes and include the roundworms and examples ascaris and finally the silo mates which have a true sealum and all the more advanced animals phylum analyta which has earthworms and leeches phylum arthropoda which has insects scorpions spiders prawns crabs and many other animals then there is phylum mollusca which has snails oysters squids Etc then there's echinodermata which includes animals like starfish there's hemichordata with worm-like animals present in Marine Waters and then there is the most advance of all phyla core data which includes mammals birth reptiles fish and us