Introduction 🔹 The kingdom Animalia consists of multicellular organisms that are classified based on their levels of organization, body symmetry, and coelom (body cavity).🔹 This classification helps in understanding structural complexity, evolutionary relationships, and functional adaptations in different animal groups. Classification of Animalia Based on Structural Complexity Criteria Types Key Features Examples (Phylum) Levels of Organization Cellular […]

NOTOCHORD: CHORDATES:Animals that possess a notochord. NON-CHORDATES:Animals that do not form a notochord. Examples: Porifera to Echinoderms.

SEGMENTATION: In some animals, the body is externally and internally divided into segments with a serial repetition of at least some organs. Example: in earthworm, the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism.

Body Cavity: The presence or absence of a cavity between the body wall and the gut wall is a key factor in animal classification. COELOM: A body cavity that is fully lined by mesoderm. Coelomates: Animals that possess a true coelom. Examples include: Annelids Molluscs Arthropods Echinoderms Hemichordates Chordates PSEUDOCOELOM: […]

Animal Symmetry: Animals can be categorized based on their body symmetry. ASYMMETRY: Sponges are mostly asymmetrical.No plane passing through the center can divide them into equal halves. RADIAL SYMMETRY: Coelenterates, ctenophores, and echinoderms exhibit radial symmetry.Any plane passing through the central axis of the body divides the organism into two […]

DIGESTIVE SYSTEMS: Incomplete Digestive System: Single opening to the outside.This opening serves as both mouth and anus. Example: Platyhelminthes (flatworms). COMPLETE DIGESTIVE SYSTEM: Two openings: mouth and anus.Food enters through the mouth and waste exits through the anus. CIRCULATORY SYSTEMS: OPEN CIRCULATORY SYSTEM: Blood is pumped out of the heart.Blood […]

Levels of Organization in Animalia MULTICELLULARITY: All members of Animalia are multicellular. However, the organization of these cells varies significantly. CELLULAR LEVEL OF ORGANIZATION: Example: Sponges Description: Cells are arranged as loose aggregates. There is some division of labor among cells, but no true tissues are formed. TISSUE LEVEL OF […]

Need for Classification: There are over a million species of animals described, making classification crucial. Classification helps in organizing animals based on their similarities and differences. It also helps in assigning a systematic position to newly discovered species. Common Features Across Animal Species: Despite differences in structure and form, animals […]