Animal Kingdom

Over a million species of animals have been described, so a system of classification is needed. This chapter explains the fundamental features used to classify animals: levels of organisation (cellular, tissue, organ and organ system), symmetry (asymmetrical, radial and bilateral), the number of germ layers (diploblastic and triploblastic), the body cavity (acoelomate, pseudocoelomate and coelomate), segmentation and the presence of a notochord. You will then study the non-chordate phyla: Porifera, Coelenterata (Cnidaria), Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata, each with its distinguishing features and examples such as Sycon, Obelia, Pleurobrachia, Taenia, Ascaris, Pheretima, Apis, Pila and Asterias. Arthropoda is the largest phylum, including over two-thirds of all named species on earth. The chapter then describes phylum Chordata, with its notochord, dorsal hollow nerve cord and paired pharyngeal gill slits, and its subphyla Urochordata, Cephalochordata and Vertebrata. Finally, you will study the vertebrate classes Cyclostomata, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves and Mammalia, with their key features and examples such as Petromyzon, Scoliodon, Labeo, Rana, Calotes, Columba and Ornithorhynchus.

Detailed Worksheet: Animal Kingdom Section A - Definitions (10 marks) 1. Distinguish between diploblastic and triploblastic animals with one example each. (2 marks) 2. What is a coelom? Distinguish between pseudocoelomates and coelomates. (2 marks) 3. What is metagenesis? Give an example. (2 marks) 4. What are cnidoblasts? Where are they found? (2 marks) 5. What is the water vascular system? In which phylum is it found? (2 marks) Section B - Calculations and Applications (15 marks) 6. About 12 lakh animal species have been described, and arthropods form about two-thirds of them. Calculate the approximate number of arthropod species. If molluscs form about 8% of all species, calculate their number. (3 marks) 7. A student examined 40 animal specimens: 12 had radial symmetry, 24 bilateral and the rest were asymmetrical. Calculate the percentage of each. Name one phylum showing each type of symmetry. (3 marks) 8. Using a simple key, classify the following: an animal with a notochord only in the larval tail; an animal with notochord throughout life but no vertebral column; an animal with jaws, a cartilaginous endoskeleton and placoid scales. Name the group and give one example of each. (3 marks) 9. Compare the number of heart chambers in fishes, amphibians, reptiles (except crocodiles), crocodiles, birds and mammals. Which of these groups are homoiothermous? (3 marks) 10. Give the phylum or class and one distinguishing feature of each: Spongilla, Pleurobrachia, Fasciola, Wuchereria, Nereis, Limulus. (3 marks) Section C - Diagrams (10 marks) 11. Draw a flowchart showing the broad classification of the animal kingdom based on fundamental features. (4 marks) 12. Draw labelled diagrams of the polyp and medusa forms of coelenterates. (3 marks) 13. Draw labelled diagrams showing the transverse sections of an acoelomate, a pseudocoelomate and a coelomate animal. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Why is Arthropoda considered the most successful phylum? Explain its features and adaptations with examples. (5 marks) 15. Compare the features of Chondrichthyes and Osteichthyes. Explain why sharks must swim constantly to avoid sinking. (5 marks) 16. 'Birds and mammals both have four-chambered hearts and are warm-blooded, yet they belong to different classes.' Explain the features that distinguish Aves from Mammalia with examples. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams neatly with labels. Use correct scientific names in italics or underlined.