Animal Kingdom

NCERT Class 11 Biology Chapter 4

Animal Kingdom for Class 11 Biology and NEET: basis of classification, the non-chordate phyla and the chordate classes, with features and examples.

2 topics Updated 8 Nov 2026

With your textbook

NCERT Biology (Class 11), Chapter 4 “Animal Kingdom”, reprint 2026-27.

Checked on 19 Oct 2026.

Learn in this order

Basis of classification of animals
Levels of organisation, symmetry, germ layers, coelom, segmentation and notochord, with diagrams.

NCERT Section 4.1 12 min read 6 solved examples 12 practice questions
Classification of animals: phyla and classes
Phyla from Porifera to Chordata with examples, chordates vs non-chordates, the seven vertebrate classes.

NCERT Section 4.2 23 min read 6 solved examples 12 practice questions

levels: cellular → tissue → organ → organ system
symmetry: asymmetrical, radial (multiple planes through the axis), bilateral (one plane)
diploblastic: ectoderm + endoderm (mesoglea between); triploblastic: ectoderm + mesoderm + endoderm
coelom: body cavity lined by mesoderm
pseudocoelom: no complete mesodermal lining; acoelomate: no cavity between body wall and gut
metamerism: segments outside and inside, with serial repetition of at least some organs
notochord: mesodermal rod, dorsal, embryonic; chordates

non-chordates: Porifera to Hemichordata; chordates: Chordata
chordate developmental plan: notochord, dorsal hollow nerve cord, pharyngeal structures, post-anal tail
protochordates: Urochordata (larval tail notochord), Cephalochordata (lifelong)
Agnatha: Cyclostomata; Pisces: Chondrichthyes, Osteichthyes
Tetrapoda: Amphibia, Reptilia, Aves, Mammalia
heart chambers: fishes 2; amphibians 3; reptiles 3 (crocodiles 4); birds, mammals 4