Title 4.ANIMAL KINGDOM.pdf ✅

https://www.chemcontent.com/ 1 1.ANIMAL KINGDOM Biology Smart Booklet - NMA Edu Tech Theory + NCERT MCQs + NEET PYQs
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https://www.chemcontent.com/ 3 Basis of classification The classification of the animal kingdom is based on the different essential characteristics such as level of organization, habitat, symmetry. Levels of Organization • Cellular Level of Organization • Tissue Level of Organization • Organ Level of Organization • Organ system Level of Organization Patterns of organ systems • Digestive System (Incomplete Digestive System and Complete Digestive System) • Circulatory System • Open Type • Closed Type Body symmetry • Bilateral Symmetry • Radial Symmetry • Asymmetrical Levels of Organisation All members of Animalia are multicellular, heterotrophic eukaryotes. But, all of them do not exhibit the same pattern of organization of cells. The cells in their body are of several types. These are organized into several functional units of progressively increasing complexity. Cellular Level In this level, the body shows some division of labour among cells. They are remarkably independent and can change their form and function. It is found in sponges. The body consists of many cells arranged as loose cell aggregates but, the cells do not form tissues. Tissue Level Here, in coelenterates, the arrangement of cells is more complex. The cells performing the same function are arranged into tissues, hence is called tissue level of organization. Organ Level In Platyhelminthes and other higher phyla, tissues are grouped together to form organs, each specialized for a particular function, i.e., organ level organization is present. Organ System Level In animals like annelids, arthropods, molluscs, echinoderms and chordates, organs have associated to form functional systems, each system concerned with
https://www.chemcontent.com/ 4 a specific physiological function. This is called organ system level of organisation. Organ systems in different groups of animals exhibit various patterns of complexities. Like the digestive system in Platyhelminthes has only a single opening to the outside of the body that serves as both mouth and anus and is thus, called incomplete. A complete digestive system has two openings, i.e., mouth and anus. Symmetry The symmetry refers to the arrangement of parts on the opposite sides of the body of a three dimensional animal. On the basis of symmetry, animals can be of following types: Asymmetrical: Animals in which, any plane passes through the center does not divide them into equal halves such animals are called asymmetrical, e.g., Sponges. Symmetrical: The body of some animals can be divided into two similar equal halves by one or more planes. Such animals are called symmetrical The symmetry can be further divided as: Radial Symmetry When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry, e.g., Coelenterates, ctenophores and echinoderms. Bilateral Symmetry: In some animals, body can be divided into identical left and right halves in only one plane. This is called bilateral symmetry, e.g., Annelids, arthropods, etc.