Animal Kingdom

The Animal Kingdom is classified based on various criteria such as structure, symmetry, and level of organization.

Basis Of Classification

Classification of animals is essential for organizing the vast diversity of species based on shared characteristics.

Levels Of Organisation

The section discusses the various levels of organization in the Animal Kingdom, ranging from cellular aggregate to organ systems.

Symmetry

Symmetry in animals plays a crucial role in classification, distinguishing primarily between asymmetrical, radial, and bilateral patterns.

Diploblastic And Triploblastic Organisation

Diploblastic animals have two embryonic layers (ectoderm and endoderm), while triploblastic animals possess a third layer, mesoderm, differentiating them in terms of complexity and body organization.

Coelom

The concept of coelom is crucial for classifying animals based on the presence or absence of a body cavity lined by mesoderm, distinguishing between coelomates, pseudocoelomates, and acoelomates.

Segmentation

Segmentation refers to the external and internal division of some animal bodies into segments, allowing for serial repetition of organs.

Notochord

The notochord is a mesodermally derived structure pivotal to the classification of chordates, distinguishing them from non-chordates.

Classification Of Animals

This section discusses the classification of animals based on features such as level of organization, symmetry, and body structure.

Phylum – Porifera

Phylum Porifera consists of primitive aquatic animals known as sponges, characterized by their cellular level of organization, asymmetry, and a unique water transport system.

Phylum – Coelenterata (Cnidaria)

Coelenterata, also known as Cnidaria, are aquatic, oftentimes marine animals exhibiting a tissue level of organization, radial symmetry, and possessing unique stinging cells.

Phylum – Ctenophora

Ctenophores, or comb jellies, are marine, radially symmetrical, diploblastic organisms characterized by their unique comb plates for locomotion and bioluminescence.

Phylum – Platyhelminthes

Platyhelminthes, commonly known as flatworms, are bilaterally symmetrical, triploblastic, and acoelomate animals that include various parasitic and free-living forms.

Phylum – Aschelminthes

The Phylum Aschelminthes, commonly known as roundworms, includes diverse species characterized by their circular cross-section, organ-system level organization, and pseudocoelomate structure.

Phylum – Annelida

Annelids are segmented, coelomate organisms that exhibit organ-system level organization and bilateral symmetry.

Phylum – Arthropoda

Phylum Arthropoda includes the largest group of animals characterized by jointed appendages, segmented bodies, and an exoskeleton.

Phylum – Mollusca

Phylum Mollusca consists of diverse, unsegmented animals with a soft body, typically protected by a calcareous shell.

Phylum – Echinodermata

Echinodermata consists of marine organisms characterized by their radial symmetry, water vascular system, and an endoskeleton made of calcareous ossicles.

Phylum – Hemichordata

Hemichordata is a small group of marine animals characterized by a rudimentary structure called the stomochord, which resembles a notochord.

Phylum – Chordata

Phylum Chordata is characterized by the presence of a notochord, a dorsal nerve cord, and bilateral symmetry, with members exhibiting various defining features.

Summary

The summary discusses the classification of the animal kingdom based on fundamental features such as organization levels, symmetry, and specific distinguishing traits.

Exercises

The exercises challenge students to apply concepts of animal classification and key features discussed in the chapter.