ANIMAL KINGDOM
Complete Chapter Notes | Class 11/12 Biology & NEET
1. Introduction
The Animal Kingdom (Kingdom Animalia) consists of multicellular, eukaryotic
organisms that are heterotrophic. Classification is the backbone of Zoology,
helping us organize millions of species based on shared morphological and
anatomical features.
• Levels of Organization: Cellular, Tissue, Organ, Organ System.
• Symmetry: Asymmetry (Sponges), Radial (Cnidaria), Bilateral (Arthropoda).
• Germ Layers: Diploblastic (2 layers) and Triploblastic (3 layers).
2. Comprehensive Phylum Comparison
Phylum Symmetry Coelom Unique Features Examples
Porifera Asymmetry Absent Water Canal System; Sycon,
Choanocytes (Collar cells). Euspongia
Cnidaria Radial Absent Cnidoblasts (stinging cells); Hydra, Obelia
Polyp & Medusa.
Platyhelminthes Bilateral Absent Flame Cells for excretion; Flat Taenia,
body. Planaria
Aschelminthes Bilateral Pseudo Round body; Complete Ascaris
alimentary canal.
Annelida Bilateral Present Metamerism (segmentation); Earthworm,
Nephridia. Leech
Page 1 of 3
Complete Chapter Notes | Class 11/12 Biology & NEET
1. Introduction
The Animal Kingdom (Kingdom Animalia) consists of multicellular, eukaryotic
organisms that are heterotrophic. Classification is the backbone of Zoology,
helping us organize millions of species based on shared morphological and
anatomical features.
• Levels of Organization: Cellular, Tissue, Organ, Organ System.
• Symmetry: Asymmetry (Sponges), Radial (Cnidaria), Bilateral (Arthropoda).
• Germ Layers: Diploblastic (2 layers) and Triploblastic (3 layers).
2. Comprehensive Phylum Comparison
Phylum Symmetry Coelom Unique Features Examples
Porifera Asymmetry Absent Water Canal System; Sycon,
Choanocytes (Collar cells). Euspongia
Cnidaria Radial Absent Cnidoblasts (stinging cells); Hydra, Obelia
Polyp & Medusa.
Platyhelminthes Bilateral Absent Flame Cells for excretion; Flat Taenia,
body. Planaria
Aschelminthes Bilateral Pseudo Round body; Complete Ascaris
alimentary canal.
Annelida Bilateral Present Metamerism (segmentation); Earthworm,
Nephridia. Leech
Page 1 of 3
