NEET Biology - Unit 1- Salient features and classification of animals- Study Notes - New Syllabus

Animal Kingdom: Salient Features & Classification

Animals are multicellular, eukaryotic, heterotrophic organisms that show a wide diversity in body plan, symmetry, habitat, and mode of reproduction.

🌱 General Salient Features of Animals

• Heterotrophic: Depend on other organisms for food.
• Eukaryotic and multicellular: Cells lack cell walls.
• Locomotion: Most animals are motile at some stage of life.
• Reproduction: Sexual (common) and asexual (some groups).
• Tissue Organisation: Cells organised into tissues, organs, and organ systems.

🐚 1) Non-Chordates (up to Phyla level)

Salient Features:

• Absence of notochord at any stage of life.
• Mostly invertebrates, no backbone.
• Body symmetry: Asymmetrical, radial, or bilateral depending on the phylum.
• Coelom: Can be acoelomate, pseudocoelomate, or coelomate.
• Digestive system, circulatory system, excretory structures vary with phylum complexity.

Major Phyla of Non-Chordates:

Phylum	Salient Features	Examples	Image
Porifera	Asymmetrical, body with pores & canals, no true tissues, aquatic, filter feeders	Spongilla, Sycon
Coelenterata / Cnidaria	Radial symmetry, diploblastic, tentacles with cnidocytes, aquatic	Hydra, Obelia, Aurelia, Physalia
Platyhelminthes	Bilateral symmetry, acoelomate, dorsoventrally flattened, parasitic/free-living	Taenia, Planaria
Annelida	Bilateral, coelomate, segmented body, closed circulatory system	Earthworm, Leech, Hirudinaria
Arthropoda	Segmented body, exoskeleton of chitin, jointed appendages	Cockroach, Scorpion, Crab
Mollusca	Soft, unsegmented body, usually with shell, coelomate	Pila, Octopus, Lamellidens, Loligo
Echinodermata	Radial symmetry in adults, water vascular system, spiny skin	Starfish, Sea Urchin, Cucumaria

🦴 2) Chordates (up to Classes level)

Salient Features:

• Presence of notochord at some stage.
• Dorsal hollow nerve cord present.
• Pharyngeal gill slits at some stage of life.
• Post-anal tail present at least during embryonic development.
• Closed circulatory system (except some lower chordates).

Major Classes of Chordates:

Class	Salient Features	Examples	Images
Pisces	Aquatic vertebrates with gills, scales, fins, cold-blooded, mostly oviparous	Labeo, Catla
Amphibia	Moist skin, lungs present, tetrapod, metamorphosis from larva to adult	Frog, Salamander
Reptilia	Dry scaly skin, lungs, amniotic eggs, ectothermic	Cobra, Crocodile
Aves	Feathers, forelimbs modified as wings, warm-blooded, amniotic eggs	Crow, Pigeon
Mammalia	Hair/fur, mammary glands, warm-blooded, internal fertilization	Human, Dog, Bat

📌 Quick Recap
Non-chordates: No notochord, diverse body plans & symmetry, examples Porifera to Echinodermata.
Chordates: Notochord present, dorsal nerve cord, post-anal tail, examples Agnatha to Mammalia.
Classification based on symmetry, coelom type, skeleton type, habitat, and reproduction.