Page 1 :
Chapter, , 1.7, , Animal Kingdom, , , , , , , , Important terms and Classification of animals, “The kingdom animalia or animal kingdom is the kingdom of, consumer organisms having ingestive type of nutrition. it is the, largest kingdom, with 1.2 million members, It has numerous, organisms having different type of form, structure, organisation,, complexity and development,, General features of animals, , , , ‘The animals possess several general features which taken, together, distinguish them from the members of other kingdom., , (2) Animals are multicellular eukaryotes and in most cases, their body cells form tissues that become arranged as organs and, organ systems,, , (2) Animals have heterotrophic mode of nutrition. They get, carbon and energy by ingesting other organism or by absorbing, nutrients from them, Animals may be herbivores, camivores,, omnivores, parasites, suspension feeders or deposit feeders., , (3) Animals require oxygen for aerobic respiration., , (4) Animals are motile, possess active movement during some, stage of their life cycle, Even the sessile sponges have free, swimming larval stages., , (6) The animal body cells of nearly all species have diploid, chromosome number., , (6) Animal cells lack a cell wall this provides flexibility to their, cells, the most striking characteristic of animals., , (7) Animals are able to make rapid responses to extemal, stimuli as a result of the activity of nerve cells, muscle or contractile, tissue or both., , (8) Animals can reproduce sexually. Although some exhibit, remarkable diversity of reproductive behaviour, all are capable of, sexual reproduction,, , (9) Animal life cycle incudes stages of embryonic, development. Mitotic cell divisions (cleavage) transform the animal, zygote Into a multicellular embryo., , Terms related to classification, , (1) Anaima : Animals without red blood eg., sponges,, enidatia, mollusca, arthropoda, echinodermata, ete., , (2) Enaima : Animals with red blood e.g,, vertebrates., (3) Vivipara : Animals which give birth to young ones are, included in this subgroup eg., man, dogs, cows, etc., , (4) Ovipai nimals which lay eggs are included in this, subgroup e.g,, frogs, toads, lizanis, snakes, birds, etc., , , , (5) Anamniotes : Vertebrates without embryonic membranes, eg, fishes, amphibians, , (6) Amniotes : Vertebrates with embryonic membranes, (chotion, amnion, allantois, yolksac) e.g, repiiles, birds, mammals, , (7) Acraniata or Protochordata : Chordates without, cranium {brain box). It includes urochordata and cephalechordata,, , (8) Chordates : Animals with notochord dorsal tubular nerve, cord, paired pharyngeal ill slits, All urochordates,, cephalochordates and vertebrates are called chordates., , (9) Craniata or Vertebrate : Chordates with cranium. It induces, cyelostomes, pisces, amphibians, reptiles, birds and mammals., , (10) Nonchordates : Animals without notochord {a rod like, elastic structure which supports the body), Phylum Porifera to, phylum Hemichordata are called nonchordates., , (11) Invertebrates : Animals without vertebral column, (backbone). All the nenchordates, urochordates and, cephalochordates are collectively called invertebrates,, , (12) Levels / Grades of organization : Four levels of, , ‘organization are found in multicellular animals,, , (i) Acellular or Molecular or Protoplasmic level : It is, present in protozoans.

Page 2 :
Animal Kingdom 185, , , , , , (ii) Cellular level : The bedy consists of many cells which, may be similar or show minor division of labour. Distinct tissues, are not formed, e.g, sponges,, , (ii) Tissue level : The body is multicellular. The cells form, poorly defined tissues. The cells occur in two distinct layers or, tissues of specialized cells e.g,, coelenterates,, , {iv) Organ-system level : The body is multicellular. The cells, are organised into tissues, tissues into organs and organs into, organ systems. Except sponges and coelenterates, all the animals, of the kingdom animalia have orgen-system level of organization,, , (13) Animal body plans ; Ithave three types of body plans :, , (i) Cell aggregate plan : The body consists of a cluster or, aggregation of cells which have rudimentary differentiation but are, not organized into tissues or organs, It is found in sponges, , (ii) Blind sac plan : The body has a single cavity which, function as digestive tract and coelom both and have one opening, to the outside. The single opening functions as both mouth for, ingestion (intake of food) and anus for egestion (undigested waste, is passed out) such a digestive tract is called incomplete animals, having blind sac body plan show tissue grade body organtsation., The cells are specialized, organised into tissues and show division, of labour. It's found in coelenterates and flatworms, , (ii) Tube-within-a-Tube plan : The body has two tubes,, one formed by the body wall and the second formed within it by, the digestive tract. Digestive tract is a continuous tube-like structure, that has two opening, a mouth for ingestion and anus for egestion, such a digestive tract is called complete, In between twa tubes is, resent coslom in which are present a number of organs. Food is, digested and absorbed in the digestive tract. This type of body plan, is found in Aschelminthes upto chordates,, , Mouth and, anus, , , , ‘Mouth, , Blind sac plan (peli, , Tube-within-Tube plan, Fig : 1.7-1 Types of body plan, , (14) Animal symmetry : Body symmetry is the similarity of, parts in different regions and directions of the body. When the, body is not divisible into equal halves by any plane it is called, asymmetrical or asymmetric as lound in Amoeba and some, sponges. An animal is said to be symmetrical if its body is divisible, into equal halves by one or more planes. Four types of symmetry, found in animals are ~, , ()) Spherical symmetry : [n this type of symmetry, any, plane passing through the centre divides the body into equivalent, or mirrored, halves. Itis found in animals whose body resembles a, sphere. e.g. Pratozoans such as Volvox, Heliozoa, Radioloria,, , (ii) Radial symmetry : In this type of symmetry, a number, of simfar parts radiate out from a central axis. The body of the, individual can be divided into equal halves by any plane passing, through the centre from top to bottom. This type of symmetry is, found in some sponges (Sycon), coelenterates (eg., Hydra, jelly, fish), echinoderms (e.g., star fich), , (ii) Biradial symmetry : In this type of symmetry, only two, planes passing through the longitudinal axis. The body can be, divided into two similar halves by one or two vertical planes only., This type of symmetry is found in sea walnuts (phylum, ¢tenophora) and sea anemones (Anthozoa). The animals which, show radial and biradial symmetry have oral and aboral sides. The, oral sides is that which has mouth, whereas the aboral side is one, which is opposite to oral side., , (iv) Bilateral symmetry : In this type of symmetry, the body, can be divided into two equal halves by a median longitudinal or, sagittal plan only. The appearance of bilateral symmetry in animal, evolution was a major advancement, because bilateral animals are, much better fitted for directional (forward) movement than in, radially symmetrical animals, This type of symmetry is found in, many invertebrates and all vertebrates,, , , , , , Anterior, Asymmetric:, (Sponogitla), , ee, ; _fibistat, Proximal, Leit Dorsal Right, (Lateral) | f J (Lateral), , Rodial symmetry, (delly fish), , , , , , , , Posterior, , , , Spherical symmetry, (Wolvox), , Bilateral symmetry,, , (Lizard), , Fig : 1.7-2 Types of symmetry, , (15) Germ layers : They are primary layers of cells which, differentiate in the animal embryos at the gastrulation ‘stage. The, germ layers give rise to all the tissues/organs of the fully formed, individual, The embryos of poriferans and coelenterates have two, germ layers, the ectoderm and endoderm. These animals are called, diploblastic. The embryos of all other animals {from phylum, Platyhelminthes to. phylum Chordata) have three layers — the, ectoderm, mesoderm and endoderm. These animals are called, triplobiastic animals., , (16| Segmentation : Segmentation is a type of body form, having a linear sequence of units of segments possessing a similar, or modified structure. It occurs in three animal phyla-Annelida,, Arthropoda and Chordata., , (17) Metameric segmentation (True metamerism or, True segmentation) : It is a ype of segmentation where extemal, divisions correspond to intemal divisions. The body is often, divided both extemally and internally info a number of segments, (metameres) eg, annelids. Segmentation is mostly extemal in, arthropods and mainly intemal in man and other chordates, (wertebree, body muscles, some blood vessels and nerves),