Class 11 Biology | Animal Kingdom - V

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In this video (Page 19 of Chapter 4 – The Animal Kingdom), we explore Phylum Coelenterata (Cnidaria) — the first group of animals to show tissue-level organization and radial symmetry.
Understand their body structure, life cycle, and examples in a crisp and clear way, based on Nectar’s Class 11 Biology Book & NCERT Biology, ideal for NEET 2025 and CBSE Class 11 students.

📚 Topics Covered (Page 19):

🌊 1️⃣ Introduction to Coelenterata (Cnidaria):

Derived from Greek coelenteron = hollow cavity.

Aquatic, mostly marine; some live in colonies (e.g. Corals).

Show tissue-level organization and radial symmetry.

Body wall has two layers – ectoderm and endoderm → diploblastic.

🧬 2️⃣ General Characteristics:

Body Structure: Cylindrical or umbrella-shaped with central gastrovascular cavity (coelenteron).

Single Opening: Mouth serves for both ingestion and egestion.

Tentacles: Surround the mouth; contain cnidoblasts (stinging cells) for defense and capturing prey.

Forms:

Polyp: Cylindrical, sessile (e.g. Hydra).

Medusa: Umbrella-shaped, free-swimming (e.g. Aurelia).

Reproduction:

Asexual by budding (common in polyps).

Sexual reproduction involves alternation of generations (Metagenesis).

💡 Highlights:

First appearance of tissues in animal evolution

Explains metagenesis and cnidoblasts clearly

Based on Nectar Education’s Class 11 Biology Book & NCERT Biology

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📺 Previous Video: Phylum Porifera – General Characters & Examples (Page 18)

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