ANIMAL KINGDOM Levels Of Classification Basis Of Classification

ANIMAL KINGDOM *Levels Of Classification *Basis Of Classification *Invertebrates

Levels of organisation All members of Animalia are multicellular, yet they all don’t exhibit the same pattern of organisation of cells. The various levels of cell organisation are celullar level, tissue level, organ level and organ system. Examples for different levels of organisation. Cellular level Tissue level Organ System

Basis Of Classification *Symmetry *Diploblastic and Tripoblastic organisation *Coelom *Segmentation *Notochord

SYMMETRY Asymmetry ; Any plane that passes through the centre does not divide the organism into equal halves. Radial symmetry ; Any plane passing through the central axis of the body divides the organism into two identical halves. Bilateral symmetry ; Where the body can be divided into two identical left and right halves in

Diploblastic & Triploblastic organisation Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm are called diploblastic. In triploblastic organisation a middle mesoderm is present between ectoderm and endoderm. Coelom Body cavity lined by mesoderm are called Coelom Animals possessing coelom are called coelomates. Eg annelids. l Animals having coelom not lined by mesoderm but mesoderm present as pouches are called pseudocoelomates. Eg achelminthes. l Animals in which coelom is absent is called acoelomates Eg platyhelminthes. l

*phylum porifera *phylum coelenterata *phylum ctenophora *phylum platyhelminthes *phylum aschelminthes Invertebrates *phylum annelida *phylum arthropoda *phylum mollusca *phylum echinodermata *phylum hemichordata

� �Segmentation � In some animals, the body is externally and internally divided into segments with a series repetition of at least some organs. This is called segmentation. Notochord is a mesodermally derived rod like structure formed on the dorsal side during embryonic development in some animals. Animals with notochord are called chordates and those animals which do not form this structure are called non chordates.

PHYLUM- PORIFERA Ø Ø Ø SYCON Members of this Phylum are commonly called as sponges. They are generally marine and asymmetrical animals. These are primitive multicellular animals and have cellular level of organisation. Sponges have water transport or canal system. Water enters through minute pores (ostia) in the body wall into a central cavity, spongocoel. The water goes out through the osculum This pathway of water transport is helpful in food gathering, respiratory exchange and removal of waste.

Ø Ø Ø Choanocytes or collar cells line the spongocoel and the canals. Digestion is Intracellular. The body is supported by a skeleton made up of spicules or spongin fibres Sexes are not separate(hermaphrodite) Reproduction is sexually by formation of gametes and asexually by fragmentation Fertilization is internal and development is indirect having a larval stage. Eg: Sycon, Spongilla, Euspongia. Spongilla Euspongia

Phylum Coelenterata ADAMSIA ØThey are aquatic, mostly marine, sessile, free-living or free- swimming, radially symmetrical ØThe name cnidaria is derived from the cnidoblast or cnidocytes present on the tentacles and the body. are used for anchorage, defence and for the capture of prey. ØThey exhibit tissue level of organisation and are diploblastic. ØThey have a central gastro- vascular cavity with a single opening, hypostome. ADAMSIA ON CRAB

ØDigestion is extra cellular and intracellular. ØCnidarians exhibit two basic forms-polyp and medusa. ØPOLYP is sessile and cylindrical form like hydra, Adamsia. ØMEDUSA is umbrella- shaped and freeswimming like Aurelia or jelly fish. JELLYFISH HYDRA v. Those Cnidarians which exhibit both the forms show alternation of generation. (Metagenesis). Polyps produce medusae asexually and medusae produce polyps sexually. üEx: Physalia, Adamsia Pennatula, Gorgonia

Phylum Ctenophora v. Ctenophores are commonly called sea walnuts or comb jellies. v. They are exclusively marine and radially symmetrical. v. They have diploblastic organisation with tissue level of organisation. v. The body bears eight external rows of ciliated comb plates, which help in locomotion. Ctenoplana Pleurobrachia üDigestion is both extra cellular and intracellular. üBioluminescence is a property of ctenophores. üSexes are not separate. üReproduction takes place only by sexual means. üThey show Indirect development. Eg: Pleurobrachia, Ctenoplana

Phylum Platyhelminthes v v They have dorsoventrally flattened body, hence are called flat worms. They are almost endoparasites found in animals including human beings. They are bilaterally symmetrical, triploblastic and acoelomate animals with organ level of classification. Hooks and suckers are present in parasitic forms. Some of them absorb nutrients directly through their body surface. FASIOLA

v. Specialised cells called flame cells help in osmoregulation and excretion. v. Sexes are not separate. v. Fertilization is internal and development is through many larval stages v. Some members like Planaria possess high regeneration capacity. Ex: Taenia, Fasciola LIVER FLUKE

Phylum Aschelminthes Its body is circular in cross section, ASCARIS hence they are also called round worms. v They may be free-living, aquatic and terrestrial or parasitic in plants and animals. v They have organ system level of body organisation. v They are bilaterally symmetrical, They have triploblastic organisation and are pseudocoelomate animals. v

ANCYLOSTOMA v. Alimentary canal is complete with a well developed muscular pharynx. v. An excretory pore removes all wastes through excretory waste. v. Sexes are separate. Females are longer than males v. Fertilisation is internal and development may be direct or indirect Eg: Ascaris, Wuchereria, Acylostoma.

PHYLUM ANNELIDA ØThey maybe aquatic (marine or free living) or terrestrial and sometimes parasitic. ØThey exhibit organ system level of body organisation and are bilaterally symmetrical. ØThey are triploblastic, metamerically segmented and coelomate animals. ØTheir body surface is distinctly marked out into metameres. NEREIS

ØThey posses longitudinal and circular muscles which help in locomotion. ØAquatic annelids possess lateral appendages, parapodia, which help in swimming. ØThey have closed circulatory system. ØNephridia help in excretion and osmoregulation. ØNeural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord. ØThey may be dioecious or monoecious. PHERETIMA

PHYLUM ARTHROPODA ØThis is the largest phylum of Animalia which includes insects. ØOver 2/3 of all the known species on earth are arthropods. ØThey have organ system level of organisation. ØThey are bilaterally symmetrical, triploblastic , segmented and coelomate animals. ØThe body of arthropoda is covered bychitinous exoskeleton. ØThe body consists of head, thorax and abdomen. They have jointed appendages. SCORPION

ØRespiratory organs are gills , book lungs or tracheal system. ØCirculatory system is of open type Ø Sensory organs like antennae, eyes (simple and compound) statocysts or balance organs are present. ØExcretion takes place through malphigian tubules. ØThey are mostly dioecious. Fertilisation is usually internal. ØThey are mostly oviparous. ØDevelopment may be direct or indirect. ØEg; Apis, Bombyx, Lucifer. PRAWN SILK WORM

PHYLUM MOLLUSCA ØThey are terrestrial or aquatic. ØThey have organ system level of organisation. ØThey are triploblastic, bilaterally symmetrical, and coelomate animals ØBody is covered with calcareous shell and is unsegmented with distinct head, muscular foot and visceral hump. ØThey are the second largest animal phylum. ØA soft and spongy layer of skin forms mantle over visceral hump. OCTOPUS

ØThe space between the hump and the mantle is called the mantle cavity in which feather like gills are present. ØIt has respiratory and SEPIA excretory functions. ØThe anterior head region has sensory tentacles ØMouth contains a file like rasping organ called radula. ØThey are usually dioecious and oviparous. ØThey show indirect development. SEPIA Example : Pila, Pinctada, Sepia, Loligo, Octopus, Aplysia, Dentalium and Chaetopleura.

Phylum Echinodermata ØThey have an endoskeleton of calcareous ossicles. ØThey are marine and have organ system level of cell organisation. ØLarvae are bilaterally symmetrical and adults are radially symmetrical. ØThey are triploblastic and coelomate animals. STAR FISH SEA CUCUMBER ØThey have complete digestive system with mouth on ventral side and anus on dorsal side. ØTheir most distinctive feature is water vascular system which help in locomotion, capture and transport of food and respiration.

ØThere is no excretory system. ØSexes are separate and reproduction is sexual. ØDevelopment is indirect with free swimming larva. Examples : Asterias, Echinus, Antedon, Cucumaria and Ophiura SEA LILY SEA URCHIN

PHYLUM HEMICHORDATA ØThis Phylum was earlier a sub phylum under phylum chordata. ØThis phylum consist of a small group of worm like marine animals. ØThey have organ system level of cell organisation. SACCOGLOSSUS ØThey are bilaterally symmetrical, triploblastic and coelomate animals. ØTheir body is cylindrical and is composed of an anterior proboscis, a collar and a long trunk. ØCirculatory system is of open type. ØRespiration takes place through gills. ØExcretory organ is proboscis gland. ØSexes are separate. Fertilisation is internal. ØDevelopment is indirect. BALANOGLOSSUS EG: Balanoglossus and Saccoglossus.

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