Animal Kingdom

Animal Kingdom INVERTEBRATA OR NON-CHORDATA BASIS OF CLASSIFICATION Basis of classification are – Arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory and reproductive system. (A) Level of Organization : 1. All members of kingdom Animalia are multicellular, all of them do not exhibit the same pattern of organisation of cells. 2. For example, in sponges, the cells are arranged as loose cell aggregates, i.e., they exhibit cellular level of organisation. 3. In coelenterates, the arrangement of cells is more complex. Here the cells performing the same function are arranged into tissues, hence is called tissue level of organisation. 4. Organ level of organisation is exhibited by members of Platyhelminthes and other higher phyla where tissues are grouped together to form organs, each specialised for a particular function. 5. Organ System of organisation – Animals like Annelids, Arthropods, Molluscs,Echinoderms and Chordates, organs have associated to form functional systems, each system concerned with a specific physiological function. This pattern is called organ system level of organisation. 6. 7. 8. Organ systems in different groups of animals exhibit various patterns of complexities. For example, the digestive system in Platyhelminthes has only a single opening to the outside of the body that serves as both mouth and anus, and is hence called incomplete digestive system. A complete digestive system has two openings, mouth and anus. The circulatory system may be of two types: (ii) Closed type in which the blood is circulated through a series of vessels of varying diameters (arteries, veins and capillaries). (B) Symmetry in Animals : 1. Asymmetrical – Organisams in which any plane that passes through the centre does not divide them into equal halves. Eg. Sponges. 2. Radial Symmetry – Any plane passing through the central axis of the body divides the organism into two identical halves. Eg. – Coelenterates, Ctenophores and Echinoderms. 91 3. Bilateral Symmetry – The body can be divided into identical left and right halves in only one plane. 2. Eg. – Annelids, Arthropods etc. 3. Animal Kingdom Pseudocoelom : In some animals mesoderms is presents as scatterd pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and the animal possessing them are called Pseudocoelomates. Acoelom : The animal in which the body cavity is absent are called acoelomates. E.g. Platyhelminthes (C) Germ Layers : 1. 2. Diploblastic Animals – Where cells are arranged in two embryonic layers, an external ectoderm and internal endoderm. In between these two layers an undifferentiated layer that is mesoglea is found. E.g. Porifera, Coelenterata. Triploblastic Animal – Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm, are called triploblastic animals Eg. – Platyhelminthes to Chordates. (E) Segmentation The body is externally and internally divided into segments with a serial repetition of at least some organs. For example, in earthworm, the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism. (D) Coelom(Body cavity) : The body cavity which is lined by mesoderm is called coelom. 1. Eucoelom : Animals possessing coelom are called coelomates or eucoelomates. (F) Notochord Animals with notochord are called chordates and those animals which do not form this structure are called non-chordates, e.g., Porifera to Echinoderms. Notochord is a mesodermally derived rod-like structure. Eg. – Annelids, Molluscs, Arthropods, Echinoderms, Hemichordates, and Chordates. 92 Animal Kingdom CLASSIFICATION CHART PHYLUM - PORIFERA Pori  pore or Minut holes   Pore bearing animals Fera  to Ferre  to bear  Characteristic Features of Porifera  Porous body, Many ostia (mouth) and single osculum (Anus) and presence of flagellated choano cytes.  Presence of water canal system (Not waster vascular system because it is found in Echinoderms)  Presence of spicules or spongin fibers as exoskeleton.  Central body cavity spongocoel Example for Porifiera : (a) Sycon, (b) Euspongia, (c) Spongilla 93 Animal Kingdom Some other Charecters of Porifera– (1) Diploblastic, cellular level of body organization, mostly asymmetrical, rarely radialy symmetrical, free living. (2) All are aquaitic, mostly marine and some are fresh water. Asconoid Syconoid (3) Water canal system is the characteristic feature that is helpfull in – (i) Food gathering (ii) Gaseous exchange (iii) Removal of wastes There are Three types of canal systems. (i) Asconoid (Simplest canal) Ingressing water – Canal – Spongocoel – Osculum Ex. Lencosolenia, Olynthus (ii) Syconoid Ingressing water dermal ostia incurrent canals prosopyles radial canals apopyles osculum to outside spongocoel Ex. Scypha (iii) Leuconoid (complex and most efficient canal system) Ingressing water dermal ostia incurrent canals prosopyles flagellated chambers Apopyles to outside Ex. Euspongia Spongilla osculum excurrent canals Leuconoid (4) Flagellated choanocytes line the spongocoel and flagellated canals and responsible for –  Maintaing unidirectional water current means ostia towards osculum.  Intracellular digestion (5) Exoskeleton supports body and made up of spicules (calcium carbonate or silicious) or spongin fibres (proteinous and used as bath sponge) (6) Digestion – Sponges are carnivorous, feeds upon microfauna (small animals), Intracellular digestion with in food vacuole of choanocytes and amoeboid cells. (4) Respiration and excretion – General body surface (8) Sexuality – Hermaphrodite (9) Reproduction –  Asexual – Internal budding (Gemmule)  Sexual – oogamous type because sperms are flagellated and motile while ovum are spherical, nonmotile. 94 Animal Kingdom (10) Fertilization – External and cross fertilization (5) Cnidocytes: These are highly specialysed stining because of protandrous condition i.e. sperm get cells that contain stinging capsule filled with toxic matured before ovum hence even being hypnotoxic chemical. hermaphrodite, cross fertilization occurs. (11) Cleavage – Holoblastic, unequal (12) Development – Indirect means larval stages are present or comes during development which are morphologicaly different from the adult. Amphiblastula and parenchymula larva present in life cycle. (13) Young sponge – Olynthus is young sponge that contain many ostia and single osculum and represent There cells are meant forindividual sponge. (i) Anchorage Representative of the Phylum – (ii) Defence (iii)Prey capturing (1) Scypha – Sycon (6) Coelentron: Central gastrovascular cavity for (2) Spongilla – Fresh water sopnge extracellular digestion, with single opening hypostome (3) Euspongia – Bath sponge (mouth) (4) Euplectella – Venus flower basket, a wedding gift (7) Skeleton: Some member of phylum coelentrate in Japan as the token of together upto death. and mainly the member of class Anthozoa have (5) Hyalonema – Glass rope sponge. exoskeleton (CaCO ) responsible for formation of 3 coral reef and source of coral. Eg. Coralium PHYLUM-COELENTERATAOR CNIDERIA Red coral. (8) Polymorphism: Some members of phylum coelentrata exhibit or persist in at least two form, polyp and medusa mean exhibit polymorphism. Cnideria = Cnidae = Stinging cells (i) Polyp form: Cylendrical asexual form Eg. (cnidocyte present) Hydra, Adamsia Characteristic Features: (ii)Medusa: Umbrella shaped free swimming and sexual form. Eg. Aurelia (Jelly fish)  Presence of central gastrovascular cavity coelentron.  Presence of highly specialised cells among all animals (9) Metagenesis: Metagenesis is the alternation of generation in sexual reproduction,in which polyp are cnidocytes or stinging cells. asexually produce medusa and medusa sexually Some other characters of Coelentrata: produces polyp. (1) Habit and Habitat: All aquaitic, Mostly marine and (10) Sexuality: Mostly hermophrodite but some are some are fresh water (Hydra), sessile (Sedentary unisexual like Hydra Viridisma. and fixed in a place) or free swimming. (11) Gametogenesis: Sex cells (gametes) are formed (2) Symmetry: Radial by Interstitial cells through meiosis. (3) Body organization: Tissue level (12) Fertilization: Cross fertilization due to protondrous (4) Body wall: Diploblastic condition. (13) Cleavage: Holoblastic, unequal (14) Embryonic development: Indirect means larval stages are present. Larva - Hydrula, Planula, Ephyra 95 Animal Kingdom (3) Symmetry : Radial or biradial symmetry. Representative of the Phylum: (4) Body organization : Tissue level (5) (6) Bioluminiscence : Member of ctenophora emits light and this property called bioluminiscence (7) Sexuality : Hermaphrodite (Bisexual) (8) Reproduction : Only sexual reproduction (9) Fertilization : External (10) Cleavage and development : Spiral cleavage and indirect development with cydippid larva. Example of Colelenterata indicating outline of their body form: (a) Aurelia (Medusa) (b) Adamsia (Polyp) Coelentrata Organism – Common Name Something specific about ctenophores  Ctenophore formely included in coelentrata  Present from sea surface to depth of 3000 metre.  Commonaly called comb jellies, or sea walnuts or sea gooseberry. Hydra – water devil Physalia – Adamsia – Portuguese man  They reproduce only by sexual method but no of war alternation of generation. Sea anemone Pennatula – Sea pen Gorgonia – Sea fan Meandrina – Brain coral Coralium – Red coral  Self fertilization also occurs. Eg. Pleurobranchia, Ctenoplana, Velamen, Beroe.  Coral Reef: Formed by deposition of merine coelentrates belong to class anthozoa and reefs are diversity rich. PHYLUM-CTENOPHORA Cteno = comb Phora = ferre = to bear Body bear 8 external rows of cilliated comb plates (1) Habitat and habit : All are exclusively marine, free living and feeds upon zooplankton. (2) External morphology : Main feature is the presence of cilliated comb plates that helps in locomotion 96 PHYLUM – PLATYHELMINTHES } (1) Habit and Habitat – Mostly parasite (Endoparasite) and few are free living aquitic (Planaria). Note: Hooks and suckers are present in parasitic forms. Eg. Taenia solium Taenia saginata – Animal Kingdom Pork tapeworm – Beef tapeworm Echinococcus granulosus – Dog tapeworm Schistosoma haematobium – Blood fluke Paragonimus – Lung fluke Diplozoon – Gill fluke of fishes Fasciola hepatica – Sheep liver fluke. Planaria – (2) External morphology – Generally body asegmented or non-segment (Planaria and Fasciola) but pseudosegmented (Taenia) Highest regeneration power. (3) Symmetry – Bilateral symmetrical (4) Locomotory organ – Generally absent but cillia as locomotory organ in Planarian. (5) Body wall – Triploblastic (6) Coelome – Acoelomate. (No space b/w body wall and Alimentary canal) (7) Level of Body organisation – organ level. (8) Alimentary Canal and Digestion – Generally alimentary canal absent but incomplete alimentary canal present in Turbellaria and Trematoda). Mouth present and Anus absent. Poor digestion is seen. (9) Excretion and Osmoregulation – First excretory Organ originated in platyhelminthes as flame cells or Solenocytes or Protonephridia. (10) Respiration – Anaerobic Respiration in parasitic forms but free living form respire through general body surface. (11) Sexuality – All are bisexual (hermapbrodite) (12) Reproduction and Fertilisation – Sexual, Cross and self fertilization both, Internal fertilisation. (13) Development – Indirect Mostly with many larval stage. Larva: Tape worm (Taenia) – Onchosphere, Hexacanth, Cysticercus or bladder worm. Fasciola (Liver fluke) – Miracidium, sporocyst, radia, cercaria, Metacercaria. Example of Platyhelminhes : (a) Tape worm (b) Liver fluke Something specific about platyhelminthes: –  Body segmentation but pseudosegmentation, Bilateral symmetry, Excretory organ (flame cells) first developed in this group  Digenetic parasite – Two host , primary and secondary host are needed Fasciola hepatica Taenia solium  Parasitic form absorb nutrient through sucker or general body surface.  Cuticle on bodywall is the parasitic adaptation which prevent the organism from digestive enzymes. 97 PHYLUM – ASCHELMINTHES (1) Habit and Habitat – Free living (Aquaitic and Terrestrial). Parasite (Endoparasite in animals and plants) Animal Kingdom (11) Sexuality – Bisexual (Dioecious)  Male animal – Smaller with curved posterior end, contain copulatory pineal setae.  Female animal – Larger with straight body. Note: Meloidegyne incognitia – It is a parasite (12) Reproduction – Sexual reproduction, Internal nematode in plants. Actually it infects the roots of fertilisation. Tobaco plant and causes a great reduction in yield.  Male gamete – Sperm without tail and generally (2) External Morphology – Body asegmented, amoeboid cylendrical, Clear sexual dimorphism (Male and  Female gamete – Ova female are recognized by their morphological appearance and generally females are larger than (13) Embryonic development – Spiral cleavage with Direct or males). Indirect development. (3) Symmetry – After being cylendrical, they represent bilateral symmetry because dorsal and ventral surface  Direct development – The young ones resemble the adult. are recognised by Dorsal and Ventral Nerve cord. (4) Locomotory organ – Absent  Indirect development – Larval stage present (5) Body wall –  Larva -- Rhabdity form (Ascaris) , Filarae (Wucheria) Eg. Triploblastic Ascaris – Round worm and parasite of intestine Wuchereria – Filaria worm and parasite of lymph capillaries of hind limb. Ancyclostoma – Hook worm (7) Level of body organisation – Organ-system level. Enterobius – (8) Alimentary canal and Digestion – Complete alimentary canal with well developed muscular pharynx. Mouth and anus are clear. Incomplete digestion of food. Pin worm and parasite of human caecum, appendix Loa-loa – Eye worm and (6) Coelome – Pseudocoelomate (Clear space present between body wall and alimentary canal but not lined with mesoderm hence called pseudocoel or false coelome) causes eyeflu (9) Excretion and osmoregulation – H-shaped Something specific about Nematodes excretory system is present that is derived from single  Parasitic forms are digenetic and monogenetic both rennet cell in Ascaris. Excretory product-NH3 that Digenetic– is excreted through separate excretory pore (Separate means not through cloaca) (10) Respiration and Gaseous Exchange – Parasitic forms are anaerobic (Ascaris) but aerobic in free living forms but no respiratory organs are present and gaseous exchange occurs through general body surface. Wuchereria Monogenetic–Ascaris – Parasite of human intestine 98 PHYLUM – ANNELIDA Annulus – Small ring form (1) Habit and Habitat – May be aquatic (Marine & Fresh water) and terrestrial both, mostly free living but some are parasite (Leach). (2) External Morphology- Body rounded and flat both type but metamerically segmented (true segmented). (3) Symmetry- Bilateral (4) Locomotory organ- Chitinous setae that are connected with protractor and Retractor muscles for pulling in and out. (5) Body wall- Triploblastic, L.M.L. and C.M.L. both present in muscular layer which helps in locomotion also. (6) Coelome- first time coelome (Eucoelome) appeared in annelids. (7) Level of body organization- Organ-system (8) Body plan- Tube with in the tube plane in T.S. (9) Alimentary canal and Digestion- Complete alimentary canal and extra cellular digestion. (10) Excretion and Osmoregulation- Excretory organNephridia. Excretory substance-NH3 and urea. (11) Respiration- Aerobic and gaseous exchange through general body surface-skin (Cutaneous Respiration) (12) Body fluids and circulation- Closed blood circulatory system (13) Neural Control- Neural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord. (14) Sexuality Mostly hermaphrodite (bisexual) Eg. Earthworm, leech.  Some are unisexual (Dioecious) Eg. Neries (aquatic) (15) Reproduction and Fertilization- Sexual reproduction and cross-external fertilization in bisexual species. (16) Development- Mostly direct but rarely indirect  Larva-Trochophore. Eg. Neries- Aquatic and commonalty called sand worm/Clamworm/Ragworm Animal Kingdom Polynoe- Bioluminescent and commonly called scale worm. Pheretima- Earth worm. Hirudinaria- Blood sucking leech.  Parapodia- Locomotory organ of Nereis and parapodia are fleshy with setae. PHYLUM – ARTHROPODA Arthros = Jointed Podas = Legs or Appendages Largest phylum of kingdom Animalia because 80% (two third) animal species belongs to phylum – Arthropoda. (1) Habit and Habitat: Found in land, water, air and from snowy tops of the high mountain to the depth of the ocean. Free living and parasite (ecto-parasite) both with great economic importance also. (2) External morphology: Body segmented and divided in to head, thorox, Abdomen or cephalothorax and abdomen with jointed appendages. (3) Symmetry: Bilateral (4) Body wall: Triploblastic, outer layer is chitinous cuticle as exoskeleton. (5) Coelome: Eucoelomate but in adult form of some arthropod it reduced and replaced by haemocoel and restricted around gonads. 99 (6) Level of Body organization: Organ-system (7) Alimentary canal and Digestion: Complete alimentary canal with well developed muscular pharynx. Extra-cellular digestion (8) Excretion and osmoregulation: Malpighian tubules and green or coxal glands while excretory substance  Uric acid – Terrestrial arthropods  Ammonia – Aquatic Arthropods (9) Respiration: Aerobic and Respiratory organs are – Gills, Trachea, Book lungs (10) Body fluid and their circulation: Open circulatory System. (11) Sensory organs:  Compound and simple eyes – Photoreceptor  Antennae – Olfactory and tangoreceptor  Statocyst – For balancing (12) Sexuality: Unisexual with clear sexual dimorphism. (13) Reproduction and fertilization: Sexual and internal fertilization but embryonic developmentis outsidethe body.  Oviparous – most of the insects  Viviparous – Scorpion (14) Development: Direct and indirect both  Larva: Nymph – Cockroach Maggot – House fly Caterpillar – Butterfly and Moth Animal Kingdom Eg. Economically important arthropod Apis – Honey bee Bombyx – Silk worm Laccifer – Lac insect Palaemon – Prawn – Cholera and diorrhea  Vector– Musca (Bacteria + Protozoa) Anopheles – Malaria (Plasmodium) Culex – Filariasis (Nematod)  Poisonous – Scorpion, wasps, Bees, Scolopendra (centipede) PHYLUM MOLLUSCA Mollis = Soft Soft body that is covered by calcarious shell. Second Largest phylum. (1) Habit and Habitat: Mostly aquatic (Marine and fresh water both) but some are terrestrial (helixland snail). Mostly mollusc are predator (Squid and octopus) (2) External morphology:  Body unsegmented with distinct – (i) Head (ii) Muscular foot (iii) Visceral hump (covered by soft mantle)  Body covered by hard calcarious shell  Mantle – It is skin fold that coveres visceral hump and secretes calcareous shell. Note: Body is internally segmented in Neopelina. (3) Symmetry: Bilateral symmetrical but may become asymmetrical due to torson. Example of Arthopoda :(a) Locust (b) Butterfly (c) Scorpion (d) Prawn (4) Locomotory organ: Muscular foot as locomotary organ which helps in creeping, swimming and burrowing. (5) Body wall: Triploblastic 100 Animal Kingdom (6) Coelome: Eucoelome (true coelome) but reduced at the adult stage and restricted to pericardial cavity, exeretory and reproductive organs. (7) Level of body organization: Organ-System. (8) Alimentary canal and digestion: Well developed and Mouth contain file-like rasping organ, called radulla. (9) Respiration: Aerobic respiration. A space between shell and mantle called mantle cavity and this cavity contains feather like gills for respiration (Gills called ctenidia). (10) Body fluid and their circulation: Open circulatory system and Haemocyanin as blue coloured respiratory pigment. (11) Excretion and Osmoregulation: Basic excretory organ are metanephridia but gills also perform it. Excretory product – NH3 (12) Sensory organs: (i) Eyes-Photoreceptor and in octopus analogous to vertebrate eyes. (ii)Tentacle – Tangoreceptor present in anterior body part or head. (b) Examples of Mollusca : (a) Pila (b) Octopus Pila – Apple snail Pinctada Sepia – – Pearl oyster Cuttle fish Loligo – Squid PHYLUM – ECHINODERMATA (1) These animals have an endoskeleton of calcareous ossicles and, hence, the name Echinodermata (Spiny bodied). (2) All are marine with organ-system level of organisation. (3) The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical. (4) They are triploblastic and coelomate animals. (5) Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side. (6) The most distinctive feature of echinoderms is the presence of water vascular system which helps in locomotion, capture and transport of food and respiration. Octopus – Devil fish (7) An excretory system is absent. Aplysia – Sea hare Dentalium – Elephant tusk shell (iii) Ospharadium-Chemoreceptor for water taste and determine purity of water also. (13) Sexuality: Most of the molluscans are unisexual (Dioecious) and oviparous. (14) Reproduction and fertilization: sexual, External and internal fertilization, all are oviparous. (15) Development: Direct but usually indirect Eg. Neopilina – Connective link b/w Annelida and Mollusca. Chaetopleura – Chiton 101 Animal Kingdom  Notochord as such is not present, while buccal diverticulum with glomerulus is called stomochord. (8) Sexes are separate. Reproduction is sexual. Fertilisation is usually external. Development is indirect with free-swimming larva. Eg. Asterias - Star fish Echinus - Sea urchin  Resemble the chordates in having all the three primary chordate structures, namely gill slits, notochord and dorsal hollow nerve cord. Antedon - Sea lily  Respiration takes place through gills. Cucumaria - Sea cucumber  Excretory organ is proboscis gland. Ophiura - Brittle star  Differ from the chordates in (i) Lacking cephalization, metamerism, paired appendages, tail, exoskeleton, cloaca, living endoskeleton, haemoglobin and RBC. (ii) Containing dorsal heart (iii) Having open neurocoel (iv) Bearing numerous gonads (v) Gill slits are dorsal in position instead of lateral as in chordates (vi) Resemble the echinoderms in nervous system, coelom and larval form. They also have common habits, ecological niche and possess remarkable power of regeneration. PHYLUM : HEMICHORDATA (Connective links between Non-Chordates and Chordates)  Body is soft and unsegmented divided into proboscis, collar and trunk.  Bilaterally symmetrical; triploblastic; coelomate.  Digestive tract complete; respiration occurs through gills.  Blood colourless without corpuscles. A circulatory system is open type.  Sexes separate, development direct or indirect, larva tornaria, external fertilization  Restriction of `notochord' to the anterior part of the body draws the name Hemichordata.  Important from evolutionary point of view as they link the chordates with non chordates. E.g. Balanoglossus (tongue worm or acorn worm), Saccoglossus. 102 Animal Kingdom VERTEBRATA OR CHORDATES B. Craniata (Euchordata) : It includes single subphyla Vertebrata which is divided into two subdivisions Chordata is the most advanced animal phylum and a. Agnatha (Jawless vertebrates) : It has two includes about 45,000 living species. All the classes - Ostracodermi and Cyclostomata. chordates have certain diagnostic features. These b. Gnathostomata : It is further divided into two are present at least in some stages of development superclasses : and may be retained even in the adult as notochord; (i) Pisces : It is divided into three classes central nervous system; gill slits; tail etc. This Placodermi, Chondrichthyes and Osteichthyes. subkingdom of vertebrates from the stand-point of (ii)Tetrapoda : It is divided into four classes efficiency in the higher chordates includes the largest Amphibia, Reptilia, Aves and Mammalia. and best known groups of animals. All the vertebrates are chordates, but then all the chordates are not SUBPHYLUM : UROCHORDATA vertebrates. INTRODUCTION PHYLUM – CHORDATA All the chordates possess three unique characteristics at some stage in their life history. These diagnostic features are :  The dorsal hollow or tubular nerve cord  A longitudnal supporting notochord  A series of pharyngeal gill slits present at a stage of life cycle.  These are bilaterally symmetrical, triploblastic, coelomate with organ-system level of organisation. Largest of the deuterostome phyla.  Body is unsegmented and usually lacks tail, covered by a test or tunic composed largely of tunicin, allied to cellulose. Appendages absent.  The notochord is only present in the tail of larva and disappears in the adult.  Coelom absent; digestive tract complete  Respiratory system has two to numerous gill slits in the pharyngeal wall  Circulatory system open type; simple tubular ventral heart.  Nervous system is represented in the adult by a single dorsal ganglion.  Urochordata often referred to as protochordatas.  Phylum chordata is divided into two groups : A. Acrania (Protochordata) B. Craniata (Euchordata) A. Acrania (Protochordata) : All marine small, primitive chordates, lack a head, skull or cranium, verte bral column, jaws and brain. It is divided into two subphyla- Urochordata and Cephalochordata, chiefly on the basis of notochord present (Recent opinion removes Hemichordata as a separate phylum of invertebrates).  Larva has a hollow nerve cord. 103 Animal Kingdom  Excretion is carried out by nephrocytes, pyloric gland SUBPHYLUM : CEPHALOCHORDATA or neural gland.  Body fish-like adapted for burrowing and swimming. It lacks head, but possesses a tail.  Sexes united, always cross and external fertilization; asexual reproduction by budding; some forms exhibit  Paired appendages absent, median fins (dorsal, alternation of generations. ventral and caudal) are present.  Larva undergoes retrogressive metamorphosis.  The larva is known as Ascidian tadpole. Eg. Herdmania (Sea squirt), Salpa, Doliolum, Ascidia.  Brain is indistinct; no paired sense organs - eyes, ears, nares.  Excretory system includes paired protonephridia with solenocytes.  Notochord extends the entire length from head to tail of the body and passes ahead of the nerve cord in front. Notochord persistent throughout life.  A true enterocoelous coelom is present. It is however reduced in the pharyngeal region of atrium. EUCHORDATA/ CRANIATA SUBPHYLUM - VERTEBRATA  Body divided into head, neck, trunk and tail. Some  Sexes separate; fertilization external; Holoblastic notable exceptions are there : Fishes lack the neck, segmentation. amphibians lack both the neck and tail (exceptions  Larva undergoes progressive metamorphosis. e.g. are there), apes and man have vestigial tail. Branchiostoma (Amphioxus or Lancelet).  Have two pairs of appendages, which are in the form of fins in the fish and limbs in other vertebrates. Key Concepts Certain forms have secondarily lost one pair or both (1) Herdmania Larva (tadpole) is free swimming while the pairs of appendages. adult is fixed.  Have integument basically of two parts : an outer epidermis of stratified epithelium derived from the ectoderm and an inner dermis of connective tissue (3) Blood of tunicates is unique as it has respiratory developed from the mesoderm. pigment. It is rich in both sulphuric acid and vanadium. Vanadium is green coloured pigment.  Endoskeleton is formed of cartilage or of cartilage (2) Tunicates reverses the direction of its heart beat periodically. (4) Pyrosoma, an example of tunicates is brightly and bone. luminous at night.  Have a large coelom that contains viscera suspended (5) Tadpole larva of Herdmania is more complex than by mesentries. It is divided into a pericardial sac adult. 104 and a general body cavity. Mammals possess a separate thoracic cavity also. Animal Kingdom  All living members of this class are ectoparasites on some fishes.  The complete digestive tract of vertebrates is ventral  Skin soft and scale less. to the nerve cord, and gives rise to digestive glands  Mouth without jaws and remains permanently open. pancreas and liver.  Mouth circular and suctorial  In lower vertebrates respiratory organs are paired gills, whereas in land forms lungs are present.  Median fins with cartilaginous rays, but no paired appendages. Tail diphycercal  Besides the basic chordate characters, vertebrates  Cartilaginous endoskeleton. Cranium and vertebral column are carlilaginous. have a ventral muscular heart, Closed circulatory system; heart 2, 3 or 4 chambered; lymphatic system  Digestive system lacks stomach. Intestine with a fold, present; erythrocytes and haemoglob in are present. typhlosole  Notochord is only present in the embryonic stage, it  They are marine animals for spawning they migrate to fresh water after spawning within a few days they is replaced by vertebral column in adult forms. die. After metamorphosis their larvae return to the  Kidneys for excretion and osmoregulation and paired ocean. appendages which may be fins or limbs.  Gill slits 5 to 16 pairs  A pair of kidneys are present for excretion, and  Heart 2 chambered; poikilothermous. osmoregulation.  Two mesonephric kidneys  Endocrine glands are well developed.  Dorsal nerve cord; 8 to 10 pairs of cranial nerves  Unisexual and have single pair of gonads.  Single median olfactory sac and nostril.  Thus all vertebrates are chordates but all chordates  Auditory organ with 1 or 2 semicircular canals. are not vertebrates.  Sexes separate or united; fertilization external; development direct or with prolonged larval stage (larva is ammocoete e.g. lamprey). e.g., Lamprey (Petromyzon), Hag fish (Myxine). Fig : A jawless vertebrate - Petromyzon (B) DIVISION - GNATHOSTOMATA (A) DIVISION - AGNATHA (JAWLESS VERTEBRATES)  Jawless primitive fish like vertebrates without true Jaws and paired limbs. Class : Cyclostomata  Jawed vertebrates having true jaws and paired limbs.  All the fish and fish-like aquatic gnathostomes are placed in the superclass Pisces, whereas all the four footed terrestrial gnathostomes in the superclass Tetrapoda 105 Animal Kingdom 1. 2. 3. 4. 5. 6. Difference between Pisces and Tetrapoda Pisces Tetrapoda Exclusively aquatic 1. Aquatic or terrestrial. Some arboreal and aerial. Paired limbs, if present, as fins. 2. Paired pentadactyl limbs present. Median fins present. 3. Median fins absent. Skin usually moist and scaly. 4. Skin usually dry and cornified. Respiration aquatic, by gills. 5. Respiration aerial, by lungs. Sense organs functional in water 6. Sense organs functional in air. SUPER CLASS-I : PISCES It is divided into two classes :  Teeth are modified placoid scales which are backwoardly directed. CLASS I : Chondrichthyes  Respiratory system includes 5-7 pairs of lamelliform (Cartilaginous fishes) (plate-like) gills. Gill slits are without gill covers (opercula) except Chimaera (connecting link  Body may be laterally compressed or dorsoventrally between chondrichthyes & osteichthyes) flattened. It consists of head, trunk and tail.  Fins are supported by horny fin-rays.  The pelvic fins bear claspers in the male which are posterior in location.  Swim bladder, which regulates buoyancy, is absent due to the absence of air bladder, they have to swim contantly to avoid sinking.  There are generally two dorsal fins. The caudal fin is  Heart is two-chambered, having one auricle and one ventricle. Sinus venosus and conus arteriosus are asymmetrical (heterocercal). present. Renal portal system is well developed. Red  Skin has unicellularal epidermal mucous glands and blood corpuscles are oval. biconves and nucleated. dermal scale (placoid scales) They are poikilothermal animals. They lack the  Endoskeleton is entirely cartilaginous. Notochord is cpacity to regulate their body temperature. persistent throughout life.  There are 10 pairs of cranial nerves.  Mouth is ventral. Jaws well developed. The alimentary canal opens into the cloaca. Intestine has  Nitrogenous waste matter is urea. a scroll valve.  Sexes are separate. The reproductive ducts discharge into the cloaca. Male usually has claspers which are used for copulation. Fertilization is internal. Most forms are ovoviviparous or oviparous. Some areviviparous. Life history is simple.  Most chondrichthyes are marine. All are predaceous. Fig : Example of Cartilaginous fishes : (a) Scoliodon (b) Pristis  Some of fishes have electric orgons (Torpedo). Examples : Scoliodon Dog fish Torpedo Electric ray Trygon Sting ray Chimaera Rat or Rabbit Fish or king of herrings. 106 Animal Kingdom CLASS II : Osteichthyes (Bony fishes)  Including both marine and fresh water fishes with bony endoskeleton.  Body is often spindle-shaped and stream lined. It facilitates movement through water.  Fins are supported by cartilaginous or bony fin-rays. Pectoral and pelvic fins act as balancers and brakes during swimming. The fins lack claspers in both the sexes. There is generally a single dorsal fin. Caudal fin is homocercal. The tail helps to propel the fisn by its lateral movements.  Skin has unicellular mucous glands and dermal scales and skin is covered with cycloid/clenoid scales.  Endoskeleton is partly or wholly bony, replaced by distinct vertebrae.  Mouth is terminal or subterminal. Alimentary canal opens out by anus. Intestine generally lacks a scroll valve.  Respiratory system includes 4 pairs of gills. Gill slits covered by gill covers (opercula).  Air bladder is present which regulates buoyancy.  As-filled swin bladder is often present which acts as a buoyancy regulator. In some bony fishs, the swim bladder is used as a lung for breathing air.  Heart is 2-chambered, having one auricle and one ventricle. Sinus venosus and Conus arteriosus are present.They are poikilothermal animals, they are cold-blooded animals.  There are 10 pairs of cranial nerves.  Nitrogenous waste matter is mostly ammonia.  Sexes are generally indistinguishable externally. Fertilization is generally external. Most forms are ovipa rous. Some are ovoviviparous or even viviparous. Some fishes show parental care of eggs.  The bony fishes occur in fresh, brackish, salt, warm and cold water. Many deep sea fishes are lumines cent. Some fishes can change colours, and some can leave water and crawl on land. Most fish used as food are bony fishes. The common food fishes of India are : (a) Freshwater Species (b) Marine Species (i) Labeo rohita (Rohu) (i) Harpodon (Bombay Duck) (ii) Catla catla (Catla) (ii) Hilsa (Hilsa) Examples : Solea - flat fish, Exocoetus (Flying fish), Catla (Katla), Clarias (Magur), Aquarium - Betta (fighting fish), Pterophyllum (Angel Fish) (a) (b) Fig : Examples of Bony fishes : (a) Hippocampus (b) Catla SUPER CLASS-II : TETRAPODA CLASS : AMPHIBIA The name indicates (Gr., Amphi : dual, bios : life), amphibians can live in aquatic as well as terrestrial habitats, without scales on the skin.  First cold blooded vertebrates from evolution point of view which came to the land. They can live on land as well as in water.  Body varies in form. It may be divisible into head, neck, trunk and tail or only into head and trunk.  There are two pairs of pentadactyl limbs, each with 4-5 or fewer digits. The digits are without claws, nails or hoofs, and often have webs.  Skin is smooth moist, rich in mucous and poison glands. It is vascular and respiratory in most species. Scales are generally absent.  Endoskeleton is mostly bony. Skull is dicondylic, means has two occipital condyles. Most vertebrae are procoelous. 107 Animal Kingdom  Mouth is large and armed with teeth in the upper or lower or both the jaws. The teeth are acrodont. Vomerine teeth may also occur. Amphibians are the first vertebrates to have a true tongue. (A true tongue has muscles and is protrusible). Alimentary canal with urinary and reproductive tract leads into the cloaca.  Respiration takes place by gills, lungs, lining of buccopharygeal cavity and skin, either separately or in combination. Some forms have vocal cords and vocal sacs.  The heart is 3-chambered (Two auricles and one ventricle): Hepatic Portal system and Renal portal system is well developed. RBC are oval, biconvex and nucleated.  There are 10 pairs of cranial nerves.  The olfactory sacs are paired and dorsal. They communicate with anterior part of the bucco pahryngeal cavity by internal nares. Eyes often have movable eye lids. Middle ear with a single auditory oscicle (Collumela). There is no external ear represents by tympanum. Lateral-line sense organs present in the larvae. Fig :Examples of Amphibia : Rana CLASS- REPTILIA (Repere or Reptum = Creep or Crawl)  Reptiles represent the first class of vertebrates fully adapted for the life in dry places on land.  Predominantly terrestrial, creeping or burrowing, mostly carnivorous, air-breathing, cold-blooded, oviparous and tetrapodal vertebrates.  Limbs 2 pairs, pentadactyl. Digits provided with horny claws. Limbs absent in all snakes.  Waste material is removed mostly as urea. Urinary bladder is present. Kidney is mesonephric but the  Exoskeleton of horny epidermal scales, shields, larva has pronephric kidney. plates and scutes.  Alimentary canal, urinary and reproductive tracts  Skin dry, cornified and devoid of glands. open into a common chamber called cloaca which  Mouth terminal. Jaws bear simple conical teeth. In opens to the exterior. turtles teeth are replaced by horny beaks.  Sexes are separate.  Alimentary canal terminates into a cloacal aperture.  Male usually lacks copulatory organ. Fertilization is external. Most forms are oviparous and development  Endoskeleton bony. Skull with one occipetal condyle (Monocondylic). is indirect  Some frogs live on trees, e.g. Hyla. Many amphibians  Respiration occurs by lungs. Only ribs help to expand and contract the trunk, making lung respiration more show parental care. Male midwife toad (Alytes) efficient than in amphibians. carries eggs round the thighs, female Surinam toad (Pipa) carries eggs in special pits on its back till  The heart usually 3 chambered and is incompletely four-chambered. Sinus venosus is present, but tadpoles become small frogs. truncus arteriosus is absent. Crocodiles have a Eg. Bufo (Toad), Rana (frog), Hyla (Tree frog), completely four-chambered heart like the birds Salamandra (Salamander), Ichthyophis (Limbless and mammals. Renal portal system is reduced. amphibia). RBC are oval, biconvex and nucleated. 108 Animal Kingdom  There are 12 pairs of cranial nerves. CLASS – AVES  Waste material is removed chiefly as uric acid in land  Feather-clad, air-breathing, warm-blooded forms and as urea in aquatic forms. Urinary bladder (homoiothermous), oviparous, bipedal flying vertebrates. may be present.  They do not have external ear, tympanum represents  Body divisible into four distince regions : head, neck, trunk and tail. Jawed bones prolonged into a ear toothless beak or bill. Neck is long and flexible. Tail  exes separate. Male usually with a muscular is short and stumpy. copulatory organ.  Limbs are two pairs. Forelimbs are modified as wings  ertilization internal. Mostly oviparous. for flying. Hindlimbs or legs are large, and variously  Large yolky eggs covered with leathery shell's adapted for walking, running, scratching, perching, embryonic membranes (amnion, chorion, yolk sac food capturing, swimming or clasping the tree and allantois) appear during development. branches.  Snakes and lizard shed their scales as skin cast.  Exoskeleton is epidermal; feathers form a nonconducting body covering for warmth, scales on the  Direct development. legs, similar to those of reptiles; claws on the toes,  Parental care usually absent. and sheaths on the beaks. Eg. : Chelone (Turtle), Testudo (Tortoise),  Endoskeleton fully ossified. Long bones are hollow Chameleon (Tree lizard), Calotes (Garden lizard), with air cavities so that called as pneumatic. Crocodilus (Crocodile), Alligator (Alligator).  Skin is dry and devoid of glands except the oil Poisonous snakes - Naja (Cobra), Bungarus (Krait), or preen gland at the root of tail. Vipera(Viper)  Pectoral muscles of flight are well developed.  Vertebral column short. Centrum of vertebrae heterocoelous (saddle-shaped).  Sternum large, usually with a vertical, mid-ventral keel for attachment of large flight muscles.  Both clavicles and single interclavicle fused to form a V-shaped bone, called furcula or wishbone.  Pelvic girdle large, strong and fused with synsaccrum throughout its length.  Skull is monocondylic.  Oesophagus frequently dilated into a crop for quick feeding and storage.  Heart completely 4-chambered. There is neither sinus venosus nor truncus arteriosus. Only right aortic (systemic) arch persists in adult. Renal portal system vestigeal.  Birds are the first vertebrates to have warm (c) (d) blood. Fig : Reptiles : (a) Chameleon (b) Crocodilus  Respiration by compact, spongy, non(c) Chelone (d) Naja distensible lungs continuous with thin-walled air sacs. 109 Animal Kingdom  Larynx without vocal cords. A sound box or syrinx, CLASS – MAMMALIA produces voice. (Mammae = Mammary gland)  Kidneys metanephric. Urinary bladder absent.  They are found in a variety of habitats polar ice caps, Birds are uricotelic i.e.excrete uric acid. deserts, mountains, forests, grasslands and dark  Cerebrum, cerebellum and optic lobes greatly caves. Body distinctly divisible into head, neck, trunk developed. Cranial nerves 12 pairs. and tail.  Olfactory organs poor. Middle ear contains a single  Limbs 2 pairs, pentadactyle, and variously adapted ossicle. Eyes large and possess nictitating membranes, for walking, running, climbing, burrowing, swimming and a vascular pecten. or flying. Hindlimbs absent in cetaceans and  Male has a pair of abdominal testes. A copulatory sirenians. organ absent except in ratitae, ducks, geese,  Hair-clad, mostly terrestrial, air-breathing, warmetc. Female has a single functional left ovary and blooded, viviparous, tetrapod vertebrates. oviduct. Exoskeleton includes horny, epidermal hair, spines,  Fertilization internal. Females oviparous. Eggs large scales, claws, nails, hoofs, horns, bony dermal plates, with much yolk and hard calcareous shell. etc. Skin richly glandular containing sweat,  Extra-embryonic membranes present. sebaceous (oil) and sometimes scent glands in both the sexes. Females have mammary glands with teats  Parental care is well marked. skin of mammals is unique in possessing hair.  The digestive tract of birds has additional chambers  A muscular partition, called diaphragm, separates the thoracic cavity from the abdominal cavity. Eg. Couous (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo(Peacock),  Endoskeleton of bone. Skull dicondylic. A single zygomatic arch present. Each half of lower jaw made Aptenodytes (Penguin), Neophron (Vulture.) of a single bone,the dentary. Alimentary canal terminates by anus, there being no cloaca except monotremes. Teeth are of several types (heterodont), borne in sockets (thecodont) and represented by two sets (diphyo dont). the crop and gizzard.  The most unique mammalian characteristics is the presence of milk producing gland (mammary g lands) by which the young one are nourished. Respiration always by lungs (pulmonary). Glottis pro tected by a epiglottis. Larynx contains vocal cords.  Heart 4-chambered with double circulation. Only the left aortic arch present. Renal portal system absent, R.B.C. small, circular and non-nucleated.  Homiothermous animals.  Kidneys metanephric. Excretion is ureotelic. Fig : Some birds : (a) Neophron (b) Struthio (c) Psittacula (d) Pavo  Brain highly evolved. Both cerebrum and cerebellum large and convoluted. Corpora quadrigemina and Corpus callosum present. Cranial nerves 12 pairs. 110 Animal Kingdom  Sense organs well developed. Eyes protected by  Fertilization internal. Except egg-laying monotremes, lids, the upper of which is movable. External ear mammals are viviparous, giving birth to living young opening protected by a large fleshy and cartilaginous ones. Parental care well developed. Mammals show flap called pinna. Middle ear cavity with 3 ear greatest intelligence among animals. ossicles-malleus, incus and stapes. Cochlea of Eg. Oviparous - Ornithorhynchus (Platypus) ; internal ear spirally coiled. Viviparous-Macropus (Kangaroo), Pteropus  Sexual dimorphism generally well marked. Male has (Flying fox), Camelus (Camel), Macaca an erectile, copulatory organ or penis. Testes com (Monkey), Rattus (Rat), Canis (Dog), Felis monly placed in a bag or scrotum outside abdomen. (Cat), Elephas (Elephant), Equus (Horse), They are viviparous with few exceptions and Delphinus (Common dolphin), Balaenoptera development is direct. (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion). Fig : Some mammals : (a) Ornithorhynchus (b) Macropus (c) Pteropus (d) Balaenoptera Salient Features of Different Phyla in the Animal Kingdom 111 Animal Kingdom 112