Animal Kingdom PDF

# ANIMAL KINGDOM ## WHAT IS AN ANIMAL? * Animals are **multicellular** and **heterotrophic** organisms without a cell wall and chlorophyll. ## 11 major phyla of Kingdom Animalia | | Phylum | Image | |---|---|---| | 1. | Porifera | A sponge | | 2. | Cnidaria | A sea anemone | | 3. | Ctenophor...

# ANIMAL KINGDOM ## WHAT IS AN ANIMAL? * Animals are **multicellular** and **heterotrophic** organisms without a cell wall and chlorophyll. ## 11 major phyla of Kingdom Animalia | | Phylum | Image | |---|---|---| | 1. | Porifera | A sponge | | 2. | Cnidaria | A sea anemone | | 3. | Ctenophora | A comb jelly | | 4. | Platyhelminthes | A flatworm | | 5. | Aschelminthes | A roundworm | | 6. | Annelida | An earthworm | | 7. | Arthropoda | A dragonfly | | 8. | Mollusca | A snail | | 9. | Echinodermata | A starfish | | 10. | Hemichordata | A acorn worm | | 11. | Chordata | A fish | ## BASIS OF CLASSIFICATION ### 1. LEVELS OF ORGANISATION * Based on organization of cells, animals are grouped into 4 levels: * **Cellular level of organization** - Cells are arranged as loose cell aggregates. E.g. Porifera. * **Tissue level of organization** - Cells are arranged into tissues. E.g. Cnidarians & Ctenophores. * **Organ level of organization** - Tissues are arranged into organs. E.g. Higher animals (Platyhelminthes to chordates). * **Organ system level of organization** - Organs are associated to organ system. Each system performs a physiological function. E.g. Higher animals. * Organ systems of different animals show complexities. E.g. * **Digestive system** is 2 types: * **Incomplete:** It has only a single opening that acts as mouth & anus. E.g. Cnidaria & Platyhelminthes. * **Complete:** It has 2 openings - mouth & anus. * **Circulatory system** is 2 types: * **Open** * **Closed** ### 2. BODY SYMMETRY * It is the arrangement of similar body parts on 2 sides of the main axis of the body. * Based on symmetry, animals are 2 types: * **Asymmetrical** - Body cannot be divided into 2 similar parts. E.g. Most poriferans, Snails etc. * **Symmetrical** - Body can be divided into 2 similar parts. * **Symmetry** is 2 types: * **Radial Symmetry** - Here, body can be divided into 2 equal halves by any plane along the central axis of the body. E.g. Some Poriferans, Cnidarians, Ctenophores and Echinoderms (adult). * **Bilateral Symmetry** - Here, body can be divided into right & left halves in only one plane. E.g. Platyhelminthes to Chordata (except adult Echinodermata). * The body of bilaterally symmetrical animal has: * A **dorsal** (upper) side * A **ventral** (lower) side * Left & right **lateral** sides * **Anterior** (cephalic) side * **Posterior** (anal or tail) side ### 3. GERMINAL LAYERS * These are layers of embryo from which all the body organs are formed. * Based on the number of germ layers, animals are 2 types: * **Diploblastic animals** * **Triploblastic animals** ### 4. COELOM (BODY CAVITY) * It is the cavity lined by mesoderm. * It is seen between the body wall & gut wall. * Coelom separates the muscles of gut & body wall. * Based on the nature of coelom, animals are 3 types: * **Acoelomate (No Coelom)** - The space between the body wall and digestive cavity is filled with matrix (parenchyma). E.g. Porifera to Platyhelminthes. * **Pseudocoelomate (False coelom)** - Here, the body cavity is not lined by mesoderm. Mesoderm is scattered pouches. E.g. Aschelminthes. * **Coelomate (True coelom)** - Here, coelom arises from mesoderm. Coelom is lined by peritoneal layer and filled with coelomic fluid. E.g. Annelida to Chordata. * **Functions of coelom:** * It accommodates visceral organs. * Coelomic fluid reduces friction between visceral organs. * It acts as shock absorber. ### 5. METAMERISM * It is the phenomenon in which the body or organs is externally and internally divided into repeated segments (metameres). * E.g. Annelids (earthworm etc.) & Arthropods. ### 6. NOTOCHORD * It is a mesodermally derived supporting rod formed on the dorsal side during embryonic development in some animals. * Animals with a notochord are called **chordates** and those without a notochord are called **non-chordates**. ## KINGDOM ANIMALIA- AT A GLANCE | Phylum | Levels of organisation | Germ layers | Symmetry | Coelom | |---|---|---|---|---| | Porifera | Cellular | - | Asymmetrical/radial | Acoelomate | | Cnidaria | Tissue | Diploblastic | Radial | Acoelomate | | Ctenophora | Tissue | Diploblastic | Radial | Acoelomate | | Platyhelminthes | Organ & Organ system | Triploblastic | Bilateral | Acoelomate | | Aschelminthes | Organ system | Triploblastic | Bilateral | Pseudocoelomate | | Annelida | | | | | | Arthropoda | | | | | | Mollusca | Organ system | Triploblastic | Bilateral | Coelomates | | Echinodermata | | | | | | Hemichordata | | | | | | Chordata | | | | |