The backbone lacking animals are called invertebrates. Based on their structure they are classified into different phyla. The following list contains examples of characters of each phyla and the classification of each invertebrate phylum with examples. PROTOZOA AN INTRODUCTION TO PROTOZOA GENERAL CHARACTERS OF PROTOZOA CLASSIFICATION OF PROTOZOA OSMOREGULATION OR HOMEOSTASIS IN PROTOZOA PSEUDOPODIA IN PROTOZOA FLAGELLUM IN PROTOZOA STRUCTURE OF ELPHIDIUM (POLYSTOMELLA) LIFE HISTORY OF ELPHIDIUM PORIFERA AN INTRODUCTION TO PORIFERA CHARACTERISTICS OF PHYLUM PORIFERA CLASSIFICATION OF PHYLUM PORIFERA PORIFERA – AFFINITIES - SYSTEMATIC POSITION OF SPONGES PORIFERA LARVA – PARENCHYMA AND AMPHIBLASTULA LARVA GEMMULE IN PORIFERA CHOANOCYTES – COLLAR CELLS SYCON SPONGE (SCYPHA) STRUCTURE AND ITS CANAL SYSTEM AND NUTRITION CANAL SYSTEM IN SYCON SPONGE HISTOLOGY OF SYCON-SPONGE SPICULES IN SYCON SPONGE REPRODUCTION IN SYCON SPONGE CNIDARIA AN INTRODUCTION TO COELENTERATA CNIDARIANS: CHARACTERISTICS AND CLASSIFICATION OF PHYLUM COELENTERATA POLYMORPHISM IN COELENTERATES CORAL REEFS: TYPES AND FORMATION FORMATION OF CORALS AND TYPES STRUCTURE OF JELLYFISH (AURELIA) HISTOLOGY OF AURELIA (JELLYFISH CELLS) JELLYFISH (AURELIA): LOCOMOTION, RESPIRATION, EXCRETION, NERVOUS SYSTEM AND SENSE ORGANS JELLYFISH (AURELIA): GASTRO VASCULAR SYSTEM AND NUTRITION JELLYFISH REPRODUCTION: AURELIA LIFE HISTORY PLATYHELMINTHES AN INTRODUCTION TO PHYLUM PLATYHELMINTHES CHARACTERISTICS OF PHYLUM PLATYHELMINTHES CLASSIFICATION OF PHYLUM PLATYHELMINTHES PARASITIC ADAPTATIONS IN HELMINTHS STRUCTURE OF FASCIOLA HEPATICA (LIVER FLUKE) LIFE HISTORY OF FASCIOLA HEPATICA (LIVER FLUKE) DEVELOPMENT OF PLANOCERA ANNELIDA AN INTRODUCTION TO PHYLUM ANNELIDA ANNELIDA: CHARACTERS AND CLASSIFICATION METAMERISM IN ANNELIDA COELOM AND COELOMODUCTS OF ANNELIDA TROCHOPHORE LARVA EXTERNAL CHARACTERS OF HIRUDINARIA ANATOMY OF HIRUDINARIA DIGESTIVE SYSTEM OF HIRUDINARIA AND ITS ADAPTATIONS HIRUDINARIA: EXCRETORY SYSTEM AND NEPHRIDIUM STRUCTURE & FUNCTION HAEMOCOELOMIC SYSTEM OF HIRUDINARIA HIRUDINARIA: NERVOUS SYSTEM AND SENSE ORGANS REPRODUCTIVE SYSTEM IN HIRUDINARIA ARTHROPODA AN INTRODUCTION TO PHYLUM ARTHROPODA PHYLUM ARTHROPODA: CHARACTERISTICS AND CLASSIFICATION ONYCHOPHORA (PERIPATUS): STRUCTURE AND AFFINITIES CHILOPODA AND DIPLOPODA STRUCTURE OF PALAEMON (FRESH WATER PRAWN) PALAEMON (FRESHWATER PRAWN) APPENDAGES DIGESTIVE SYSTEM OF PALAEMON (PRAWN) RESPIRATORY SYSTEM OF PALAEMON PALAEMON (PRAWN): BLOOD VASCULAR SYSTEM PALAEMON (PRAWN): REPRODUCTIVE SYSTEM PALAEMON (PRAWN): EXCRETORY SYSTEM PALAEMON (PRAWN): NERVOUS SYSTEM AND SENSE ORGANS