{"id":5206,"date":"2026-01-04T17:11:38","date_gmt":"2026-01-04T11:41:38","guid":{"rendered":"https:\/\/vajiramandravi.com\/upsc-exam\/?p=5206"},"modified":"2026-01-05T11:28:04","modified_gmt":"2026-01-05T05:58:04","slug":"animal-kingdom-classification-characteristics-and-examples","status":"publish","type":"post","link":"https:\/\/vajiramandravi.com\/upsc-exam\/animal-kingdom-classification-characteristics-and-examples\/","title":{"rendered":"Animal Kingdom – Classification, Characteristics and Examples"},"content":{"rendered":"

Animalia is one of the\u00a0five kingdoms\u00a0<\/strong>of the living world. Animal kingdom can be broadly categorised according to a number of fundamental characteristics such as\u00a0segmentation, notochord, coelom, symmetry, level of organisation, and cell organisation<\/strong>. In addition to the basic traits, each phylum or class has a variety of other unique characteristics.<\/p>\r\n

As more than a million species of animals have been found so far, the need for classification and a proper\u00a0taxonomy\u00a0<\/strong>of these animals becomes important, which helps to assign a systematic position to any newly described species.<\/p>\r\n

Basis of Classification<\/h2>\r\n

Though animals differ in their structure and form, there are some basic features that are common to individuals such as - arrangement of cells, body symmetry, coelom nature, digestive pattern, circulatory systems, respiratory systems, etc., which are taken together for the animal classification.<\/p>\r\n

Levels of Organisation<\/h3>\r\n

Although all the members of Animalia are multicellular, they do not exhibit the same pattern in the organisation of cells. There are certain labour divisions (activities) within the cells.<\/p>\r\n

\"levels<\/p>\r\n

    \r\n\t
  • In coelenterates, the cell arrangement is more complex. Here, the cells performing the same function are arranged into tissues; hence, this is called the\u00a0tissue level of organisation<\/strong>.<\/li>\r\n\t
  • A still higher level of organisation -\u00a0organ level<\/strong>, is exhibited by members of Platyhelminthes and other higher phyla, where tissues are grouped together to form organs, each specialised for a particular function.<\/li>\r\n\t
  • In animals like Annelids, Arthropods, Molluscs, Echinoderms, and Chordates,\u00a0organs are associated to form functional systems<\/strong>, each concerned with a specific physiological function. This pattern is called the\u00a0organ system level of organisation<\/strong>.<\/li>\r\n\t
  • There are two possible\u00a0types of circulatory systems<\/strong>:\r\n\r\n
      \r\n\t
    • the open type:<\/strong>\u00a0in which the blood is pumped out of the heart and the cells and tissues are directly bathed in it and<\/li>\r\n\t
    • a closed type:<\/strong>\u00a0in which the blood is circulated through a series of vessels of varying diameters (arteries, veins and capillaries).<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

      Symmetry<\/h3>\r\n

      Animals can be categorised based on their symmetry.<\/p>\r\n

      \"symmetry\"<\/p>\r\n

        \r\n\t
      • In asymmetrical animals, any plane that passes through the centre does not divide them into equal halves. Example:\u00a0Sponges<\/strong>.<\/li>\r\n\t
      • It is called radial symmetry when any plane passing through the body's axis splits the organism into two identical halves.\r\n\r\n
          \r\n\t
        • Examples:\u00a0echinoderms, coelenterates, and ctenophores<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n\t
        • Other animals like\u00a0annelids, arthropods<\/strong>, etc., in which the body can be divided into identical left and right halves in only one plane, exhibit\u00a0bilateral symmetry.<\/strong><\/li>\r\n<\/ul>\r\n

          Diploblastic and Triploblastic Organisation<\/h3>\r\n

          \"diploblastic<\/p>\r\n

            \r\n\t
          • Diploblastic:<\/strong>\u00a0These animals have two embryonic layers of cells, an internal endoderm and an external ectoderm.\r\n\r\n
              \r\n\t
            • For example -\u00a0coelenterates<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n\t
            • Triploblastic:<\/strong>\u00a0In these animals, the developing embryo has a third germinal layer, the mesoderm, in between the ectoderm and endoderm.\r\n\r\n
                \r\n\t
              • Examples:\u00a0Platyhelminthes to chordates<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                Coelom<\/h3>\r\n

                One of the very important bases of classification is the presence or absence of a cavity, called Coelom, which is present between the gut wall and the body wall.<\/p>\r\n

                \"coelom\"<\/p>\r\n

                  \r\n\t
                • Animals possessing coelom are called\u00a0coelomates<\/strong>.\r\n\r\n
                    \r\n\t
                  • Examples-\u00a0annelids, molluscs, arthropods, echinoderms, hemichordates and chordates<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n\t
                  • In certain animals, the pseudo-coelom is found and the animals possessing it are called\u00a0pseudocoelomates<\/strong>.\r\n\r\n
                      \r\n\t
                    • Examples:\u00a0Aschelminthes<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n\t
                    • The animals in which the body cavity is absent are called\u00a0acoelomates<\/strong>.\r\n\r\n
                        \r\n\t
                      • For example-\u00a0Platyhelminthes<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                        Segmentation<\/h3>\r\n

                        In certain animals, the body is segmented both inside and outside, with at least some organs repeating serially.<\/p>\r\n

                          \r\n\t
                        • Despite having some type of serial repetition in their units, many taxa\u2014such as the molluscs\u2014are not typically thought of as segmented.<\/li>\r\n\t
                        • Animals classified as segmented may have imitated organs or a body made up of self-similar units, but the term \"segmented\" usually refers to an organism's component parts.<\/li>\r\n<\/ul>\r\n

                          \"segmentation\"<\/p>\r\n

                            \r\n\t
                          • For example, in earthworms, the body shows a pattern called\u00a0metameric segmentation\u00a0<\/strong>and the phenomenon is known as\u00a0metamerism.<\/strong><\/li>\r\n<\/ul>\r\n

                            Notochord<\/h3>\r\n

                            The notochord is a rod-like structure formed on the dorsal side at the time of embryonic development in certain animals.<\/p>\r\n

                            \"chordates\"<\/p>\r\n

                              \r\n\t
                            • The animals that have notochord are known as chordates and those that do not have this structure are known as non-chordates\r\n\r\n
                                \r\n\t
                              • For example-\u00a0Porifera to Echinoderms<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                                Classification of Animals<\/h2>\r\n

                                Based on the different classification factors discussed above, animals are classified into different phyla. The characteristics of these phyla and associated animals are described below.<\/p>\r\n

                                \"classification<\/p>\r\n

                                \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
                                Phylum<\/strong><\/td>\r\nFeatures<\/strong><\/td>\r\nExamples<\/strong><\/td>\r\n<\/tr>\r\n
                                Porifera<\/strong><\/td>\r\n\r\n

                                - Generally known as\u00a0sponges<\/strong><\/p>\r\n

                                - Primarily\u00a0marine, asymmetric animal<\/strong><\/p>\r\n

                                - Primitive multicellular<\/p>\r\n

                                - Possess water transport or canal system.<\/p>\r\n

                                - Exhibit\u00a0Intracellular digestion\u00a0<\/strong><\/p>\r\n

                                -\u00a0Sexes not separate<\/strong>\u00a0(eggs and sperm are produced by the same individual).<\/p>\r\n

                                -\u00a0Reproduction:<\/strong>\u00a0both sexual (creating gametes) and asexual (fragmentation).<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Sycon\u00a0<\/strong>(Scypha),<\/p>\r\n

                                \"sycon\"<\/p>\r\n

                                -\u00a0Spongilla\u00a0<\/strong>(Freshwater sponge)<\/p>\r\n

                                \"spongilla\"<\/p>\r\n

                                - Other examples:\u00a0<\/strong>Euspongia<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Coelenterata<\/strong><\/td>\r\n\r\n

                                - These are aquatic, mostly marine, sessile or free-swimming,<\/p>\r\n

                                - Radially symmetrical<\/strong>.<\/p>\r\n

                                - The stinging capsules, or nematocysts, are found on the tentacles and body of the cnidoblasts or cnidocytes (source of the name cnidaria)<\/p>\r\n

                                - Cnidoblasts are used for defence, anchoring, and catching prey.<\/p>\r\n

                                - Cnidarians<\/strong>\u00a0exhibit\u00a0tissue-level organisation<\/strong>\u00a0and are\u00a0diploblastic.<\/strong><\/p>\r\n

                                - They have a hypostomal mouth and a\u00a0single-entry central gastro-vascular cavity.\u00a0<\/strong><\/p>\r\n

                                -\u00a0Digestion<\/strong>\u00a0is extracellular and intracellular.<\/p>\r\n

                                - Some cnidarians, such as corals, have a skeleton made up of calcium carbonate.<\/p>\r\n

                                - The\u00a0two fundamental body forms<\/strong>\u00a0that cnidarians display are\u00a0polyps and medusa.<\/strong><\/p>\r\n

                                  \r\n\t
                                • Polyp is a sessile and cylindrical form like Hydra, Adamsia, etc., whereas the medusa is umbrella-shaped and free-swimming like Aurelia or jellyfish.<\/li>\r\n<\/ul>\r\n

                                  - Those cnidarians that exist in both forms exhibit alternation of generation (metagenesis), that is, polyps produce medusae asexually and medusae form the polyps sexually (example-\u00a0Obelia<\/strong>).<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Physalia\u00a0<\/strong>(Portuguese man-of-war)<\/p>\r\n

                                \"physalia\"<\/p>\r\n

                                -\u00a0Adamsia<\/strong>\u00a0(Sea anemone)<\/p>\r\n

                                \"adamsia\"<\/p>\r\n

                                -\u00a0Other examples:<\/strong><\/p>\r\n

                                  \r\n\t
                                • Pennatula (Sea-pen)<\/li>\r\n\t
                                • Gorgonia (Sea-fan)<\/li>\r\n\t
                                • Meandrina (Brain coral).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                Ctenophora (Cnidaria)\u00a0<\/strong><\/td>\r\n\r\n

                                - Generally known as sea walnuts or comb jellies.<\/p>\r\n

                                - These are exclusively marine, radially symmetrical, diploblastic organisms with tissue-level organisation.<\/p>\r\n

                                - Digestion is both extracellular and intracellular.<\/p>\r\n

                                - They exhibit\u00a0bioluminescence,<\/strong>\u00a0the ability to emit light.<\/p>\r\n

                                - Sexes are not separate.<\/p>\r\n

                                - only sexual reproduction.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Pleurobrachia\u00a0<\/strong><\/p>\r\n

                                \"pleurobrachia\"<\/p>\r\n

                                -\u00a0Ctenoplana<\/strong><\/p>\r\n

                                \"ctenoplana\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Platyhelminths<\/strong><\/td>\r\n\r\n

                                - Have\u00a0dorso-ventrally flattened bodies;<\/strong>\u00a0hence, called\u00a0flatworms<\/strong><\/p>\r\n

                                - Are\u00a0endoparasites,\u00a0<\/strong>found in animals including human beings.<\/p>\r\n

                                - re\u00a0bilaterally symmetrical, triploblastic and acoelomate animals with organ-level organisation.\u00a0<\/strong><\/p>\r\n

                                -\u00a0Sexes are not separate.\u00a0<\/strong><\/p>\r\n

                                - Internal fertilisation occurs.<\/p>\r\n

                                - Certain members, such as\u00a0Planaria<\/strong>, have a high capacity for regeneration.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Taenia\u00a0<\/strong>(tapeworm)<\/p>\r\n

                                \"taenia\"<\/p>\r\n

                                -\u00a0Fasciola\u00a0<\/strong>(liver fluke).<\/p>\r\n

                                \"fasciola\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Aschelminthes<\/strong><\/td>\r\n\r\n

                                - Known as roundworms because of their\u00a0circular body cross-section.\u00a0<\/strong><\/p>\r\n

                                - Can be free-living or parasitic, aquatic orterrestrial or parasitic<\/p>\r\n

                                -\u00a0organ-system level of body organisation<\/strong><\/p>\r\n

                                -\u00a0Bilaterally symmetrical, triploblastic and pseudocoelomate.<\/strong><\/p>\r\n

                                - Sexes are separate (dioecious)<\/p>\r\n

                                - Often, females are longer than males.<\/p>\r\n

                                - Fertilisation is internal and development may be direct (the young ones resemble the adults) or indirect.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Ascaris\u00a0<\/strong>(Roundworm)<\/p>\r\n

                                \"ascaris\"<\/p>\r\n

                                -\u00a0Wuchereria\u00a0<\/strong>(Filaria worm)<\/p>\r\n

                                \"wuchereria\"<\/p>\r\n

                                -\u00a0Ancylostoma\u00a0<\/strong>(Hookworm)<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Annelida<\/strong><\/td>\r\n\r\n

                                - Both\u00a0aquatic and terrestrial<\/strong><\/p>\r\n

                                -\u00a0free-living<\/strong>, sometimes parasitic.<\/p>\r\n

                                -\u00a0organ-system level of body organisation\u00a0<\/strong><\/p>\r\n

                                -\u00a0Bilateral symmetry<\/strong><\/p>\r\n

                                -\u00a0Triploblastic<\/strong>, metamerically segmented and coelomate animals<\/p>\r\n

                                - A\u00a0closed circulatory system<\/strong><\/p>\r\n

                                -\u00a0Nephridia:\u00a0<\/strong>Help in osmoregulation and excretion.<\/p>\r\n

                                - Reproduction is\u00a0sexual<\/strong>.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Nereis<\/strong><\/p>\r\n

                                \"nereis\"<\/p>\r\n

                                -\u00a0Pheretima\u00a0<\/strong>(Earthworm)<\/p>\r\n

                                \"pheretima\"<\/p>\r\n

                                -\u00a0Hirudinaria\u00a0<\/strong>(blood-sucking leech)<\/p>\r\n

                                \"hirudinaria\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Arthropoda<\/strong><\/td>\r\n\r\n

                                - The largest phylum of Animalia, and includes insects. (More than two-thirds of all species on earth)<\/p>\r\n

                                -\u00a0organ-system level of organisation.<\/strong><\/p>\r\n

                                - These are<\/p>\r\n

                                  \r\n\t
                                • Bilaterally symmetrical<\/strong><\/li>\r\n\t
                                • Triploblastic<\/strong><\/li>\r\n\t
                                • Segmented\u00a0<\/strong><\/li>\r\n\t
                                • Coelomate animals.\u00a0<\/strong><\/li>\r\n<\/ul>\r\n

                                  -\u00a0The chitinous exoskeleton\u00a0<\/strong>covers the arthropod body<\/p>\r\n

                                  - The body is made up of a head, thorax and abdomen.<\/p>\r\n

                                  - They have\u00a0jointed appendages<\/strong>\u00a0(arthros-joint, poda-appendages).<\/p>\r\n

                                  -\u00a0Respiratory organs<\/strong>\u00a0include gills, book gills, and book lungs.<\/p>\r\n

                                  - Open-type circulatory system.<\/p>\r\n

                                  - Presence of\u00a0sensory organs\u00a0<\/strong>like antennae, eyes, and statocysts<\/p>\r\n

                                  - Excretion takes place through malpighian tubules.<\/p>\r\n

                                  - They are mostly\u00a0dioecious<\/strong>.<\/p>\r\n

                                  -\u00a0Fertilisation\u00a0<\/strong>is usually\u00a0internal<\/strong>.<\/p>\r\n

                                  - They are mostly\u00a0oviparous<\/strong>.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Apis\u00a0<\/strong>(Honey bee)<\/p>\r\n

                                \"apis\"<\/p>\r\n

                                -\u00a0Bombyx\u00a0<\/strong>(Silkworm)<\/p>\r\n

                                \"bombyx\"<\/p>\r\n

                                -\u00a0Other examples:<\/strong><\/p>\r\n

                                  \r\n\t
                                • Laccifer (Lac insect) Vectors \u2013 Anopheles, Culex and Aedes (Mosquitoes)<\/li>\r\n\t
                                • Gregarious pest \u2013 Locusta (Locust)<\/li>\r\n\t
                                • Living fossil \u2013 Limulus (King crab<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                Mollusca<\/strong><\/td>\r\n\r\n

                                - Second largest animal phylum<\/p>\r\n

                                - These are<\/p>\r\n

                                  \r\n\t
                                • terrestrial or aquatic\u00a0<\/strong>(marine or freshwater)<\/li>\r\n\t
                                • Of\u00a0organ-system level of organisation<\/strong><\/li>\r\n\t
                                • Bilaterally symmetrical<\/strong><\/li>\r\n\t
                                • triploblastic\u00a0<\/strong><\/li>\r\n\t
                                • coelomate<\/strong><\/li>\r\n<\/ul>\r\n

                                  - Body<\/p>\r\n

                                    \r\n\t
                                  • covered with a\u00a0calcareous shell<\/strong><\/li>\r\n\t
                                  • unsegmented\u00a0<\/strong>with a distinct head,<\/li>\r\n\t
                                  • muscular foot<\/li>\r\n\t
                                  • visceral hump.<\/li>\r\n<\/ul>\r\n

                                    - Mantle is made up of a soft and spongy layer of skin over the visceral hump.<\/p>\r\n

                                    -\u00a0Mantle cavity:<\/strong>\u00a0The space between the hump and the mantle<\/p>\r\n

                                      \r\n\t
                                    • feather-like gills are present in it.<\/li>\r\n<\/ul>\r\n

                                      - They have respiratory and excretory functions.<\/p>\r\n

                                      -\u00a0Sensory tentacles:<\/strong>\u00a0at the anterior head<\/p>\r\n

                                      -\u00a0Radula:<\/strong>\u00a0A file-like rasping organ for feeding in the mouth.<\/p>\r\n

                                      - Usually\u00a0dioecious\u00a0<\/strong>and\u00a0oviparous<\/strong><\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Pila\u00a0<\/strong>(Apple snail)<\/p>\r\n

                                \"pila\"<\/p>\r\n

                                -\u00a0Pinctada\u00a0<\/strong>(Pearl oyster)<\/p>\r\n

                                \"pinctada\"<\/p>\r\n

                                -\u00a0Other examples:<\/strong><\/p>\r\n

                                  \r\n\t
                                • Sepia (Cuttlefish)<\/li>\r\n\t
                                • Loligo (Squid)<\/li>\r\n\t
                                • Octopus (Devil fish)<\/li>\r\n\t
                                • Aplysia (Seahare)<\/li>\r\n\t
                                • Dentalium (Tusk shell)<\/li>\r\n\t
                                • Chaetopleura (Chiton).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                Echinodermata<\/strong><\/td>\r\n\r\n

                                - Have an\u00a0endoskeleton\u00a0<\/strong>of calcareous ossicles, hence the name Echinodermata<\/p>\r\n

                                - Are:<\/p>\r\n

                                  \r\n\t
                                • Marine<\/li>\r\n\t
                                • Of organ-system level of organisation\u00a0<\/strong><\/li>\r\n\t
                                • Triploblastic and coelomate<\/strong><\/li>\r\n\t
                                • Adult are radially symmetrical and the larvae are bilaterally symmetrical.<\/li>\r\n<\/ul>\r\n

                                  - Have\u00a0a complete digestive system<\/strong><\/p>\r\n

                                  -\u00a0Distinctive features:\u00a0<\/strong>the presence of a water vascular system, helping in locomotion, capture and transport of food and respiration.<\/p>\r\n

                                  -\u00a0excretory system is absent.\u00a0<\/strong><\/p>\r\n

                                  -\u00a0Sexes\u00a0<\/strong>are separate.<\/p>\r\n

                                  -\u00a0Reproduction is sexual.\u00a0<\/strong><\/p>\r\n

                                  -\u00a0Fertilisation\u00a0<\/strong>is usually external.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Asterias\u00a0<\/strong>(Star fish)<\/p>\r\n

                                \"asterias\"<\/p>\r\n

                                -\u00a0Echinus\u00a0<\/strong>(Sea urchin)<\/p>\r\n

                                \"Echinus\"<\/p>\r\n

                                -Other examples:<\/strong><\/p>\r\n

                                  \r\n\t
                                • Antedon (Sea lily)<\/li>\r\n\t
                                • Cucumaria (Sea cucumber)<\/li>\r\n\t
                                • Ophiura (Brittle star).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                Hemichordata<\/strong><\/td>\r\n\r\n

                                - Contains stomochord, a structure similar to the\u00a0notochord<\/strong>.<\/p>\r\n

                                - Have a small group of worm-like marine animals<\/p>\r\n

                                -\u00a0organ-system level of organisation.<\/strong><\/p>\r\n

                                -\u00a0Bilaterally symmetrical, triploblastic\u00a0<\/strong>and\u00a0coelomate animals.<\/strong><\/p>\r\n

                                - The body is cylindrical and is made up of an anterior proboscis, a collar and a long trunk.<\/p>\r\n

                                - Open-type\u00a0circulatory system<\/strong><\/p>\r\n

                                - Respiration through gills.<\/p>\r\n

                                -\u00a0Sexes\u00a0<\/strong>are separate.<\/p>\r\n

                                -\u00a0Fertilisation\u00a0<\/strong>is external.<\/p>\r\n<\/td>\r\n

                                		\r\n

                                -\u00a0Balanoglossus<\/strong><\/p>\r\n

                                \"balanoglossus\"<\/p>\r\n

                                -\u00a0Saccoglossus<\/strong>.<\/p>\r\n

                                \"saccoglossus\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                Chordata<\/strong><\/td>\r\n\r\n

                                - Basically characterised by\u00a0notochord presence<\/strong>, a dorsal hollow nerve cord and paired pharyngeal gill slits<\/p>\r\n

                                -\u00a0Bilaterally symmetrical<\/strong><\/p>\r\n

                                - Triploblastic, coelomate with organ-system level of organisation.<\/p>\r\n

                                -\u00a0A closed circulatory system<\/strong><\/p>\r\n

                                - Divided into three subphyla:<\/p>\r\n

                                  \r\n\t
                                • Urochordata or Tunicata,<\/li>\r\n\t
                                • Cephalochordata<\/li>\r\n\t
                                • Vertebrata.<\/li>\r\n<\/ul>\r\n

                                  - Urochordata and Cephalochordata are known as\u00a0protochordate\u00a0<\/strong>and are exclusively marine.<\/p>\r\n

                                  - Notochord presence:<\/p>\r\n

                                    \r\n\t
                                  • In urochordata, only in larval tail<\/li>\r\n\t
                                  • In cephalochordata extends from head to tail and is persistent throughout their lives.<\/li>\r\n<\/ul>\r\n<\/td>\r\n
                                		\r\n

                                - Urochordata \u2013\u00a0Ascidia<\/strong>, Salpa, Doliolum<\/p>\r\n

                                \"urochordata\"<\/p>\r\n

                                - Cephalochordata \u2013\u00a0Branchiostoma\u00a0<\/strong>(Amphioxus or Lancelet).<\/p>\r\n

                                \"branchiostoma\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/figure>\r\n

                                Classification and Characteristics of Vertebrata<\/h3>\r\n

                                The defining feature of this subphylum of chordata is the presence of a\u00a0vertebral column (spine or backbone).\u00a0<\/strong>The members of Vertebrates possess\u00a0notochord\u00a0<\/strong>during the\u00a0embryonic period<\/strong>\u00a0but it is replaced by the cartilaginous or bony\u00a0vertebral column in adulthood<\/strong>.<\/p>\r\n

                                  \r\n\t
                                • Thus, all vertebrates are chordates but not all chordates are vertebrates.<\/li>\r\n\t
                                • Besides the basic chordate characters, vertebrates have a ventral muscular heart with two, three or four chambers, kidneys for excretion and osmoregulation, and paired appendages, which may be fins or limbs.<\/li>\r\n<\/ul>\r\n

                                  \"division<\/p>\r\n

                                  \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
                                  Class<\/strong><\/td>\r\nFeatures<\/strong><\/td>\r\nExamples<\/strong><\/td>\r\n<\/tr>\r\n
                                  Cyclostomata<\/strong><\/td>\r\n\r\n

                                  - All members of this class are\u00a0ectoparasites<\/strong>\u00a0living on some fish.<\/p>\r\n

                                  - They have an elongated body with 6-15 pairs of gill slits for\u00a0respiration<\/strong>.<\/p>\r\n

                                  - They lack jaws and have a circular, sucking mouth.<\/p>\r\n

                                  - The body does not consist of scales and paired fins.<\/p>\r\n

                                  - The cranium and vertebral column are cartilaginous.<\/p>\r\n

                                  - Closed type\u00a0circulation\u00a0<\/strong><\/p>\r\n

                                  - Marine but can migrate to freshwater for spawning.<\/p>\r\n

                                  - After undergoing metamorphosis, their larvae return to the ocean.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  -\u00a0Petromyzon\u00a0<\/strong>(Lamprey)<\/p>\r\n

                                  \"petromyzon\"<\/p>\r\n

                                  -\u00a0Myxine\u00a0<\/strong>(Hagfish).<\/p>\r\n

                                  \"myxine\"<\/p>\r\n<\/td>\r\n<\/tr>\r\n

                                  Chondrichthyes<\/strong><\/td>\r\n\r\n

                                  - These are marine animals with streamlined bodies and a cartilaginous endoskeleton.<\/p>\r\n

                                  - The mouth is located ventrally.<\/p>\r\n

                                  - Notochord is persistent throughout life.<\/p>\r\n

                                  - The gill slits are distinct and devoid of opercula.<\/p>\r\n

                                  - Tough skin having minute placoid scales.<\/p>\r\n

                                  - Teeth are modified placoid scales that are backwardly directed.<\/p>\r\n

                                  - Their jaws are very powerful.<\/p>\r\n

                                  - These animals are predaceous.<\/p>\r\n

                                  - Due to the absence of an air bladder, they have to swim constantly to avoid sinking.<\/p>\r\n

                                  - The heart is two-chambered (auricle and ventricle).<\/p>\r\n

                                  - Some have electric organs (such as torpedoes) and some possess poison stings (such as trigon).<\/p>\r\n

                                  - They are cold-blooded (poikilothermous) animals.<\/p>\r\n

                                  - Sexes are separate.<\/p>\r\n

                                  - They have internal fertilisation<\/p>\r\n

                                  - Many of them are viviparous.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  -\u00a0Scoliodon\u00a0<\/strong>(Dogfish)<\/p>\r\n

                                  \"scoliodon\"<\/p>\r\n

                                  -\u00a0Pristis\u00a0<\/strong>(Sawfish)<\/p>\r\n

                                  \"pristis\"<\/p>\r\n

                                  -\u00a0Other examples:<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Carcharodon (Great white shark)<\/li>\r\n\t
                                  • Trygon (Sting ray).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                  Osteichthyes<\/strong><\/td>\r\n\r\n

                                  - Includes both marine and freshwater fish with bony endoskeletons.<\/p>\r\n

                                  - Body is streamlined.<\/p>\r\n

                                  - Mouth is mostly terminal<\/p>\r\n

                                  - Possess four pairs of gills, each with an operculum covering them.<\/p>\r\n

                                  - An air bladder is present and regulates buoyancy.<\/p>\r\n

                                  - Heart is two-chambered (auricle and ventricle).<\/p>\r\n

                                  - Cold-blooded animals.<\/p>\r\n

                                  - Sexes are separate.<\/p>\r\n

                                  - Fertilisation is usually external.<\/p>\r\n

                                  - They are oviparous and development is direct.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  -\u00a0Exocoetus\u00a0<\/strong>(Flying fish)<\/p>\r\n

                                  \"exocoetus\"<\/p>\r\n

                                  -\u00a0Labeo\u00a0<\/strong>(Rohu)<\/p>\r\n

                                  \"labeo\"<\/p>\r\n

                                  -\u00a0Other examples:\u00a0<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Hippocampus (Sea horse)<\/li>\r\n\t
                                  • Catla (Katla)<\/li>\r\n\t
                                  • Clarias (Magur)<\/li>\r\n\t
                                  • Betta (Fighting fish)<\/li>\r\n\t
                                  • Pterophyllum (Angelfish).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                  Amphibia<\/strong><\/td>\r\n\r\n

                                  - In both aquatic and terrestrial habitats.<\/p>\r\n

                                  - Most have two pairs of limbs.<\/p>\r\n

                                  - The body can be separated into a head and a trunk.<\/p>\r\n

                                  - Some have tails<\/p>\r\n

                                  - Skin is moist (without scales).<\/p>\r\n

                                  - The eyes have eyelids.<\/p>\r\n

                                  - A tympanum represents the ear.<\/p>\r\n

                                  - Alimentary canals, urinary and reproductive tracts open into a common chamber called the cloaca, which opens to the exterior.<\/p>\r\n

                                  - Respiration is done by the gills, lungs and skin.<\/p>\r\n

                                  -\u00a0Heart with three chambers:<\/strong>\u00a0one ventricle and two auricles.<\/p>\r\n

                                  -\u00a0Cold-blooded<\/strong>\u00a0animals.<\/p>\r\n

                                  - Sexes are separate.<\/p>\r\n

                                  - Fertilisation is external.<\/p>\r\n

                                  - Oviparous<\/p>\r\n

                                  - Development is indirect.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  - Bufo (Toad)<\/strong><\/p>\r\n

                                  \"bufo\"<\/p>\r\n

                                  - Rana (Frog)<\/strong><\/p>\r\n

                                  \"rana\"<\/p>\r\n

                                  -\u00a0Other examples:<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Hyla (Tree frog)<\/li>\r\n\t
                                  • Salamandra (Salamander),<\/li>\r\n\t
                                  • Ichthyophis (Limbless amphibia).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                  Reptilia<\/strong><\/td>\r\n\r\n

                                  -\u00a0creeping or crawling mode of locomotion.<\/strong><\/p>\r\n

                                  -\u00a0Mostly terrestrial\u00a0<\/strong><\/p>\r\n

                                  - Epidermal scales, scutes, or dry, cornified skin cover the body.<\/p>\r\n

                                  - no external ear openings.<\/p>\r\n

                                  - The tympanum represents the ear.<\/p>\r\n

                                  - Limbs, when present, are two pairs.<\/p>\r\n

                                  - three-chambered hearts (only\u00a0crocodiles have four)<\/strong><\/p>\r\n

                                  - Scales are shed by snakes and lizards as skin casts.<\/p>\r\n

                                  -\u00a0Sexes\u00a0<\/strong>are separate.<\/p>\r\n

                                  -\u00a0Fertilisation\u00a0<\/strong>is internal.<\/p>\r\n

                                  - Oviparous<\/p>\r\n

                                  - Development is direct.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  -\u00a0Chelone\u00a0<\/strong>(Turtle)<\/p>\r\n

                                  \"chelone\"<\/p>\r\n

                                  -\u00a0Testudo\u00a0<\/strong>(Tortoise)<\/p>\r\n

                                  \"testudo\"<\/p>\r\n

                                  -\u00a0Other examples:\u00a0<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Chameleon (Tree lizard)<\/li>\r\n\t
                                  • Crocodilus (Crocodile)<\/li>\r\n\t
                                  • Alligator<\/li>\r\n\t
                                  • Poisonous snakes \u2013 Naja (Cobra)<\/li>\r\n\t
                                  • Bangarus (Krait)<\/li>\r\n\t
                                  • \u00a0Vipera (Viper).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                  Aves (Birds)<\/strong><\/td>\r\n\r\n

                                  - Characteristic features<\/p>\r\n

                                    \r\n\t
                                  • Presence of\u00a0feathers\u00a0<\/strong><\/li>\r\n\t
                                  • Most of them can fly,<\/strong>\u00a0except flightless birds (such as ostriches).<\/li>\r\n<\/ul>\r\n

                                    - The forelimbs are modified into wings.\u00a0<\/strong><\/p>\r\n

                                    - Hind limbs generally have scales<\/p>\r\n

                                      \r\n\t
                                    • These are modified for walking, swimming or clasping the tree branches.<\/li>\r\n<\/ul>\r\n

                                      - With the exception of the oil gland at the base of the tail, the skin is gland-free and dry.<\/p>\r\n

                                      - Endoskeleton is fully\u00a0ossified\u00a0<\/strong>(bony)<\/p>\r\n

                                      -\u00a0Pneumatic bones<\/strong>\u00a0(long, hollow, with air cavities), help in flying.<\/p>\r\n

                                      -\u00a0digestive tracts include extra chambers\u00a0<\/strong>called the crop and gizzard (similar to the human stomach)<\/p>\r\n

                                      -\u00a0four<\/strong>-chambered<\/strong>\u00a0heart<\/p>\r\n

                                      - Warm-blooded<\/p>\r\n

                                      - Respiration by the lungs.<\/p>\r\n

                                      -\u00a0Sexes\u00a0<\/strong>are separate.<\/p>\r\n

                                      -\u00a0Fertilisation\u00a0<\/strong>is internal.<\/p>\r\n

                                      - Oviparous<\/p>\r\n

                                      - Development is direct.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  - Corvus (Crow)<\/strong><\/p>\r\n

                                  \"corvus\"<\/p>\r\n

                                  - Columba (Pigeon)<\/strong><\/p>\r\n

                                  \"columba\"<\/p>\r\n

                                  -\u00a0Other examples:<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Psittacula (Parrot)<\/li>\r\n\t
                                  • Struthio (Ostrich)<\/li>\r\n\t
                                  • Pavo (Peacock)<\/li>\r\n\t
                                  • Aptenodytes (Penguin)<\/li>\r\n\t
                                  • Neophron (Vulture).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n
                                  Mammalia<\/strong><\/td>\r\n\r\n

                                  -\u00a0Found in different environments<\/strong><\/p>\r\n

                                  - Some have adapted to fly or live in water.<\/p>\r\n

                                  - unique characteristic: the presence of milk-producing glands (mammary glands), by which the young ones are nourished<\/p>\r\n

                                  - Possess two sets of limbs that are designed for different activities<\/p>\r\n

                                  - Unique skin possessing hair<\/p>\r\n

                                  -\u00a0External ears<\/strong><\/p>\r\n

                                  - Different types of teeth in the jaw.<\/p>\r\n

                                  - The heart is four-chambered.<\/p>\r\n

                                  - Homoiothermous.<\/p>\r\n

                                  - Respiration by the lungs<\/p>\r\n

                                  - Sexes are separate<\/p>\r\n

                                  - Fertilisation is internal.<\/p>\r\n

                                  - Viviparous with few exceptions<\/p>\r\n

                                  - Development is direct.<\/p>\r\n<\/td>\r\n

                                  		\r\n

                                  -\u00a0Platypus<\/strong><\/p>\r\n

                                  \"platypus\"<\/p>\r\n

                                  -\u00a0Kangaroo<\/strong><\/p>\r\n

                                  \"kangaroo\"<\/p>\r\n

                                  -\u00a0Other examples:<\/strong><\/p>\r\n

                                    \r\n\t
                                  • Pteropus (Flying fox)<\/li>\r\n\t
                                  • Camelus (Camel)<\/li>\r\n\t
                                  • Macaca (Monkey)<\/li>\r\n\t
                                  • Rattus (Rat)<\/li>\r\n\t
                                  • Canis (Dog)<\/li>\r\n\t
                                  • Felis (Cat)<\/li>\r\n\t
                                  • Elephas (Elephant)<\/li>\r\n\t
                                  • Equus (Horse)<\/li>\r\n\t
                                  • Delphinus (Common dolphin)<\/li>\r\n\t
                                  • Balaenoptera (Blue whale)<\/li>\r\n\t
                                  • Panthera tigris (Tiger)<\/li>\r\n\t
                                  • Panthera leo (Lion).<\/li>\r\n<\/ul>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/figure>","protected":false},"excerpt":{"rendered":"

                                    The Kingdom Animalia, with two major groupings, vertebrates and invertebrates, is the most evolved of all the animal kingdoms. These are multicellular and heterotrophic eukaryotes.<\/p>\n","protected":false},"author":6,"featured_media":8308,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[173],"tags":[315,40],"class_list":{"0":"post-5206","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-quest-level-3","8":"tag-animal-kingdom","9":"tag-quest"},"acf":[],"_links":{"self":[{"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/posts\/5206","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/comments?post=5206"}],"version-history":[{"count":1,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/posts\/5206\/revisions"}],"predecessor-version":[{"id":19983,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/posts\/5206\/revisions\/19983"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/media\/8308"}],"wp:attachment":[{"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/media?parent=5206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/categories?post=5206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vajiramandravi.com\/upsc-exam\/wp-json\/wp\/v2\/tags?post=5206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}