Animalia

Animalia Animal kingdom is divided into two sub-kingdoms, the Parazoa and ­Eumetazoa based on their organisation. . Parazoa : These include the multicellular sponges and their cells are loosely aggregated and do not form tissues or organs. . Eumetazoa : These include multicellular animals with well defined tissues, which are organised as organs and organ systems. Eumetazoans includes two taxonomic levels called grades. They include Radiata and Bilateria . (FWRGHUP 0HVRGHUP 0HVRGHUP (QGRGHUP 'LJHVWLYH FDYLW\ $$FRHORPDWH )ODWZRUPV %3VHXGRFRHORPDWH URXQGZRUPV 3VHXGRFRHORP &&RHORPDWHPROOXVFV DQQHOLGVDUWKURSRGV HFKLQRGHUPVDQGFKRUGDWHV 0HVHQWHU\ (FWRGHUP (QGRGHUP &RHORP Figure . Diagrammatic representation of coelom in animals What is the advantage of true coelom over a pseudocoelom? . . Segmentation and Notochord In some animals, the body is ­externally and internally divided into a series of ­repeated units called segments with a ­serial repetition of some organs ­ (Metamerism) . The simplest form of segmentation is XI Std Biology-Zoology Chapter- Kingdom Cellular level Porifera Radial Bilateral Platyhelminthes Aschelminthes Annelida Arthropoda Mollusca Echinodermata Hemichordata Chordata Without body cavity (aceolomates) Coelenterata (Cnidaria) Ctenophora With false coelom (pseudocoelomates) With true coelom (coelomates) Tissue/Organ/ Organ system Animalia (multicellular) Symmetry Phylum Levels of Organisation Body Cavity or Coelom Division : Deuterostomia ( deuteron : secondary; stomium : mouth) Eumetazoans in which anus is formed from or near the blastopore and the mouth is formed away from the blastopore. It ­includes only one subdivision Enterocoelomata. They have a true coelom called enterocoel, formed from the archenteron.