Best Zoology animal Kingdom

Animal Kingdom (Class 11 – All Phyla Description) The Animal Kingdom includes multicellular, eukaryotic and heterotrophic organisms that lack a cell wall. Animals show holozoic nutrition, locomotion, and mostly sexual reproduction. Based on body organisation and complexity, animals are divided into Parazoa and Eumetazoa. Porifera are asymmetrical, cellular-level organisms with pores and canal systems (sponges). Cnidaria (Coelenterata) show tissue-level organisation, radial symmetry, and stinging cells. Ctenophora are marine, radially symmetrical animals with comb plates for movement. Platyhelminthes are dorsoventrally flattened worms with organ-level organisation. Nematoda (Aschelminthes) are cylindrical, unsegmented pseudocoelomates. Annelida possess true segmentation and closed circulatory systems. Arthropoda, the largest phylum, have jointed appendages and chitinous exoskeletons. Mollusca have soft bodies, muscular foot, and usually a shell. Echinodermata are marine animals with spiny skin and radial symmetry in adults. Hemichordata show primitive chordate features. Chordata possess notochord, dorsal nerve cord, pharyngeal gill slits, and post-anal tail at some stage of life. Classification is based on level of organisation, symmetry, germ layers, body cavity, segmentation, and presence of notochord.