Biology · Class 11 Science

Ch 4Animal Kingdom — Class 11 Biology, concept-first.

Animals show an extraordinary diversity of body forms, yet classifying this diversity in a scientifically useful way requires looking past superficial resemblance and habitat to a set of shared, fundamental features of body organisation.

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Levels Of Organisation

The grades of body organisation in animals — cellular, tissue, organ and organ-system levels — reflecting increasing structural complexity.

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4.1

Basis of Classification — Levels of Organisation and Symmetry

4.2

Diploblastic and Triploblastic Organisation, Coelom, Segmentation and Notochord

Diploblastic and triploblastic organisation. During embryonic development, the cells of the embryo arrange themselves into distinct layers, called germ layers, from which all the adult tissues and org…

4.3

Phylum Porifera

The phylum Porifera (Latin porus, pore + ferre, to bear) comprises the sponges, the simplest and most primitive of the multicellular animals, standing at the cellular level of organisation — a sponge'…

4.4

Phylum Coelenterata (Cnidaria) and Phylum Ctenophora

Phylum Coelenterata (Cnidaria). Members of this phylum are found almost entirely in aquatic, chiefly marine, habitats, living either fixed to a substratum (sessile, e.g.

4.5

Phylum Platyhelminthes and Phylum Aschelminthes

Phylum Platyhelminthes. Commonly called flatworms because the body is characteristically dorsoventrally flattened, this phylum may be free-living (mostly aquatic, e.g.

4.6

Phylum Annelida

Phylum Annelida takes its name from the Latin annulus, a little ring, referring to the externally visible rings, or segments, into which the whole body — both the outer body wall and, correspondingly,…

4.7

Phylum Arthropoda

Phylum Arthropoda (Greek arthros, joint + podos, foot) is by a very wide margin the largest phylum in the entire Animal Kingdom, containing more described species than every other phylum of animals co…

4.8

Phylum Mollusca and Phylum Echinodermata

Phylum Mollusca (Latin molluscus, soft) is, after Arthropoda, the second largest phylum of the Animal Kingdom, and is remarkable for the diversity of body forms built on essentially the same soft-bodi…

4.9

Phylum Hemichordata and Phylum Chordata — General Features

Phylum Hemichordata is a small group of worm-like, exclusively marine animals — historically classified as a subphylum of Chordata because of certain superficial resemblances, but now recognised as a…

4.10

Chordate Classes I — Cyclostomata, Chondrichthyes and Osteichthyes

Class Cyclostomata (Greek kyklos, circle + stoma, mouth) comprises the most primitive living vertebrates, the only survivors of the jawless (Agnatha) vertebrate line.

4.11

Chordate Classes II — Amphibia, Reptilia, Aves and Mammalia

Class Amphibia (Greek amphi, both + bios, life) comprises animals capable of living both in water and on land, a dual existence reflected in the class name.

4.12

Summary — Revising the Animal Kingdom by Classification Criteria

This chapter has surveyed the Animal Kingdom through ten non-chordate phyla — Porifera, Coelenterata (Cnidaria), Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinoderma…