>        Phylum-Annelida Includes Metamerically Segmented Animals With True Schizocoelous Coelom. They May Be Aquatic (Marine And Freshwater) Or Terrestrial, Free-Living And Sometimes Parasitic.

>        They Exhibit Organ-System Level Of Body Organisation And Bilateral Symmetry. Their Body Surface Is Distinctly Marked Into Segments (Or) Metameres.

>        They Possess Longitudinal And Circular Muscles Which Help In Locomotion. Locomotory Organs Are Minute Rod-Like Setae (Or) Suckers. Their Aquatic Species Like Nereis Possesses Lateral Appendages, Parapodia Which Help In Swimming.

>        Respiration Is By Moist Skin (Or) Gills Of Parapodia.

>        Their Excretory System Consists Of Metamerically Distributed Coiled Tubes Called Nephridia.

>        Animal Can Be Monoecious (Earthworm) Or Dioecious (Nereis).

>        Reproduction Can Be Direct (Or) Indirect With A Trochophore Larva.

>        Phylum-Arthropoda Is The Largest Phylum Of Animal Kingdom Which Includes Insects.

>        They Are Triploblastic, Coelomate And Bilaterally Symmetrical Animals. The Body Of Arthropods Is Covered By Sclerites (Chitinous Exoskeleton) Which Are Shed At Regular Intervals During Growth And Development By A Process Called Ecdysis (Or) Moulting.

>        These Animals Are Metamerically Segmented With Regionalisation Of Segments Called Tagmatisation. Their Body Is Divisible Into Head, Thorax And Abdomen.

>        They Have Jointed Appendages Adapted For Food Ingestion, Locomotion, Respiration, Copulation, etc. Their Respiratory Organs Are Gills (In Prawn), Trachea (In Insects), Book-Lungs (In Scorpion) And Book-Gills (In Horse-Shoe Crab).

>        Circulatory System Is Open Type And Circulating Blood Is Haemolymph.

>        Sensory Organs Like Antennae, Eyes (Compound And Simple), Statocysts (Or) Balancing Organs Are Present.

>        Excretion Is By Coxal (Or) Green Glands (e.g. Arachinds) Or Malpighian Tubules (e.g. Insects) As Nephridia Is Absent. They Are Mostly Dioecious And Have Internal Fertilisation.

>        Development Is Direct (Or) Indirect With One To Several Larval Stages. In Some, Like Honeybees Parthenogenesis Is Also Seen.

>        Arthropods Are Economically Important As Well Like Prawn And Crab Are Eaten Up As Food. Insects Like Apis (Honeybees), Bombyx (Silkworm), Laccifer (Lac Insect) Give Honey, Silk And Lac, Respectively. Some Insects Are Also Vectors For Various Human Diseases Like Anopheles (Malaria), Aedes (Dengue), Etc.

>        Phylum-Mollusca Includes Soft Bodies Animals. These Are Terrestrial (Or) Aquatic (Marine Or Freshwater) Having An Organ-System Level Of Organisation.

>        They Are Bilaterally Symmetrical, Triploblastic, Coelomate Animals.

>        Body Is Covered By Calcareous Shell And Is Unsegmented With A Distinct Head, Muscular Foot And Visceral Hump. A Soft And Spongy Layer Of Skin Forms A Delicate Covering Over The Visceral Hump Called The Mantle. The Space Between The Hump And The Mantle Is Called The Amntte Mantle Cavity In Which Feather-Like Gills Are Present.

>        Gills Have Respiratory And Excretory Function. The Mouth Contains A File-Like Rasping Organ For Feeding Called Radula.

>        Excretion Occurs By Paired Sac-Like Kidneys (Metanephridia). These Kidneys Are Called Organ Of Bojanus In Unio. Their Respiratory Pigment Is Haemocyanin.

>        Molluscs Are Dioecious And Oviparous With Indirect Development With Veliger (In Pila), Trochophore Or Glochidium Larva (In Unio). These Animals Are Pila (Apple Snail), Neopilina (Living Fossil), Chiton (Sea Mouse), Octopus (Devil Fish), Loligo (Squid), Etc.

>        Phylum-Echinodermata Includes Spiny Skinned Animals. Their Endoskeleton Is Of Calcareous Ossicles And Hence Named Echinodermata.

>        All Of The Species Are Marine With Organ Level Of Organisation.

>        The Adult Echinoderms Are Radially Symmetrical But Larvae Are Bilaterally Symmetrical. They Are Triploblastic And Coelomate Animals. Digestive System Is Complete With Mouth On The Lower (Ventral) Side And Anus On The Upper (Dorsal) Side.

>        They Have Characteristic Ambulacral (Or) Water Vascular System That Helps In Locomotion, Capture, Transport Of Food And Respiration. They Have Open Circulatory System But Blood Lacks Respiratory Pigment. An Excretory System Is Absent.

>        Sexes Are Septate, But Lack Sexual Dimorphism. Reproduction Is Sexual, Fertilisation Is External With Indirect Development. The Larval Forms In Echinoderms Are Dipleural, Brachiolaria, Bipinnaria, Pluteus, Ophipluteus, Echinopluteus, Aericularia And Doliolaria. These Animals Are Asterias (Star Fish), Echinus (Sea Urchin), Antedon (Feather Star), Etc.            

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