# Animal Kingdom Notes, Class 11 Biology | SwaVid Animal Kingdom, NCERT Class 11 Biology: notes with key ideas, key terms, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-11/biology/chapter/animal-kingdom Source: https://www.swavid.com/cbse/class-11/biology/chapter/animal-kingdom # Animal Kingdom ## Key terms ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 11 Biology on SwaVid ### Basis of classification ### Basal non-chordates ### Worm phyla ### Arthropods, molluscs, and echinoderms ### Hemichordates and chordates ### Vertebrata divisions and classes ### Next chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 11 › Biology › Animal Kingdom Notes written by SwaVid from the NCERT textbook. Class 11 Biology, Chapter 4. Key ideas, formulas and common mistakes. CBSE prints 15 marks for Unit I, not for this chapter alone. Short answer. This chapter classifies multicellular animals based on body symmetry, germ layers, coelom, and organ systems. It outlines the defining features and examples of non-chordate and chordate phyla. Source: NCERT Biology (Reprint 2026-27) , Chapter 4, Animal Kingdom Animals are classified using levels of organisation, body symmetry, embryonic germ layers, nature of coelom, segmentation, and presence of a notochord. Levels range from cellular to organ-system, with complete or incomplete digestive systems and open or closed circulatory systems. Porifera have a cellular level of organisation with a water canal system. Coelenterata and Ctenophora exhibit radial symmetry and tissue-level organisation, with cnidoblasts in cnidarians and comb plates in ctenophores. Platyhelminthes are bilateral, acoelomate, and dorso-ventrally flattened with flame cells for excretion. Aschelminthes are pseudocoelomate with an unsegmented body, whereas Annelida show true metameric segmentation and a true coelom. Arthropoda is the largest phylum, characterised by jointed appendages and a chitinous exoskeleton. Mollusca possess a soft unsegmented body often covered by a calcareous shell, while adult echinoderms display radial symmetry and a water vascular system. Hemichordata have a worm-like body divided into proboscis, collar, and trunk. Chordates are defined by a notochord, dorsal hollow nerve cord, and paired pharyngeal gill slits at some stage of life. Vertebrates replace the notochord with a vertebral column and divide into Agnatha and Gnathostomata. Gnathostomata contains Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia based on adaptations like fins, limbs, skin coverings, and heart chambers. Try each question first. Then tap it to see the answer. Mesodermal pouches scattered between ectoderm and endoderm define a pseudocoelom. The only animal phylum with a pseudocoelomic body plan is Aschelminthes. Pseudocoelomate; Phylum Aschelminthes Starfish belongs to Phylum Echinodermata. Larval echinoderms have bilateral symmetry, while adult echinoderms have radial symmetry. Larva is bilaterally symmetrical; adult is radially symmetrical Cephalochordates are characterized by a persistent notochord from head to tail throughout life. A standard NCERT example of Cephalochordata is Branchiostoma (Amphioxus or Lancelet). Subphylum Cephalochordata; Branchiostoma Morphology of Flowering Plants . Biological Classification . The 19 chapters of Class 11 Biology . CBSE does not give marks to one chapter. It prints 15 marks for Unit I, Diversity of Living Organisms, which includes Animal Kingdom. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Morphology of Flowering Plants. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Ch 4 NCERT book - 15 marks, Unit I - 3 quick checks - Confusing the water canal system with the water vascular system . Identify Porifera by the water canal (transport) system with ostia and osculum, and Echinodermata by the water vascular system used for locomotion and respiration. - Classifying Aschelminthes as acoelomate or true coelomate . Remember that Aschelminthes are the only pseudocoelomates, having mesoderm scattered in pouches rather than forming a continuous lining. - Assuming all chordates retain a notochord throughout life . Note that urochordates retain it only in the larval tail, cephalochordates retain it from head to tail throughout life, and vertebrates replace it with a vertebral column in adults. - Treating Hemichordata as a subphylum of Chordata . Treat Hemichordata as an independent non-chordate phylum because the stomochord in its collar region is structurally distinct from a true notochord. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 11](https://www.swavid.com/cbse/class-11) - [Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup) - [All 19 chapters](https://www.swavid.com/cbse/class-11/biology/chapters) - [NCERT Biology (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/morphology-of-flowering-plants) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/biological-classification) - [Class 11 Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup)