Classification Of Animal Kingdom

The classification of Animal Kingdom is a crucial part of biological classification, where scientists organize animals based on shared features. This structured system enables biologists and students to understand evolutionary relationships and characteristics across diverse species. Animals are multicellular heterotrophs, and the study of their grouping is called taxonomy. This article delves into the basis of classification of animals, the Animal Kingdom hierarchy, and phylum-level distinctions — as per Kingdom Animalia classification in the CBSE  syllabus.

Basis of Classification of Animals

Animals in the Animal Kingdom (Kingdom Animalia) are classified based on several criteria:

• Symmetry: Animals may show radial symmetry (e.g., Cnidaria) or bilateral symmetry (e.g., Platyhelminthes).
• Germ Layers: Based on the number of embryonic layers, animals are diploblastic (two layers) or triploblastic (three layers).
• Body Cavity (Coelom): Classification includes acoelomate (no cavity), pseudocoelomate (false cavity), and coelomate (true cavity) animals.
• Level of Organization: Ranges from cellular level (e.g., Porifera) to organ-system level (e.g., Chordata).
• Segmentation and Cephalization: Some animals exhibit metamerism (segmentation) and development of a head region (cephalization).
• Notochord: Presence or absence of a notochord divides animals into chordates and non-chordates.

Animal Kingdom Hierarchy

The Animal Kingdom classification chart starts from the Kingdom and branches into smaller groups:

Kingdom → Phylum → Class → Order → Family → Genus → Species

Non-Chordates (Invertebrates)

Non-chordates are animals without a notochord and form the vast majority of animal species. They include:

1. Porifera

• Example: Sponges
• Characteristics: Cellular level of organization, no symmetry, acoelomate

2. Cnidaria (Coelenterata)

• Example: Jellyfish, Hydra
• Characteristics: Radial symmetry, diploblastic, tissue-level organization

3. Ctenophora

• Example: Comb jellies
• Characteristics: Radial symmetry, bioluminescence, diploblastic

4. Platyhelminthes

• Example: Flatworms
• Characteristics: Bilateral symmetry, triploblastic, acoelomate

5. Nematoda

• Example: Roundworms
• Characteristics: Bilateral symmetry, pseudocoelomate, unsegmented

6. Annelida

• Example: Earthworms, Leeches
• Characteristics: Segmented, bilateral, true coelom

7. Arthropoda

• Largest phylum with over 1 million species
• Example: Insects, Crustaceans
• Characteristics: Jointed appendages, chitinous exoskeleton

8. Mollusca

• Example: Snails, Octopus
• Characteristics: Soft body, shell, true coelom

9. Echinodermata

• Example: Starfish, Sea Urchins
• Characteristics: Radial symmetry in adults, water vascular system

Chordates (Vertebrates)

Chordates possess a notochord, dorsal nerve cord, and pharyngeal slits at some stage in life.

1. Urochordata and Cephalochordata (Protochordates)

• Example: Amphioxus, Sea squirts
• Notochord present only in larvae or entire life

2. Vertebrata

Divided into:

• Pisces (Fishes) – Cold-blooded, aquatic
• Amphibia – Moist skin, live both on land and water
• Reptilia – Dry scaly skin, lay eggs
• Aves (Birds) – Feathers, flight, warm-blooded
• Mammalia – Mammary glands, warm-blooded, hair or fur

Phylum-Wise Classification Summary (Table)

Conclusion

Understanding the classification of Animal Kingdom helps us appreciate the diversity and complexity of animal life. From simple sponges to intelligent mammals, classification gives structure to biology, supporting deeper learning in zoology and systematics. Whether you’re preparing for Class 11 biology, NEET, or simply curious about the biological classification of animals, this framework remains foundational.

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