NEWNMCLE

1.ZOOLOGY TIPS

.Aristotle (384-322 B.C.) known as father of Biology , Zoology and Embryology.

.Two kingdom classification was proposed by Carolous Linnaeus.

.Three kingdom classification was proposed by Earnest Haeckel.

.Four kingdom classification was developed by Copeland.

.Carolous Linnaeus father of modern taxonomy.

.R.H. Whittaker (1969), an American taxonomist, divided all the organisms into five kingdoms. As the viruses are on the border line of living and non-living, they have been left out.

.Whittaker’s five kingdom includes Monera , Protista, Plantae , Fungi and Animalia.

.The Kingdom Animalia includes sponges , corals , worms , insects ,snails, starfishes ,sharks , bonyfishes , frog , lizards , snakes, turtles , crocodiles , birds and mammals.

.Animals excel all other organisms in diversity.

.They are consumer organisms of various orders. They form links in different food chains and complex food webs.

.The earliest animals arose in the sea during the Precambrian era. Most phyla existing today appeared in the beginning of the combrian period about 570 million years ago.

.Over a million species of animals have been described till now. These species differ in structure and form.

.Inspite of these differences , there are fundamental features common to various individual with the arrangement of cells , body symmetry , nature of coelom, patterns of various organ-system etc.

.The study of general animal features reveals evolutionary trends in almost each structure and function.

.A gradual improvement is noticeable from the lower towards the higher animals.

.These features are used as the basis of animal.

ORGANIZATION OF ANIMAL BODY

.Scheme of organization

.Animals are multicellular, heterotrophic eukaryotes.

.The cells in their body are of several types, and are organized into functional units of progressively increasing complexity.

.The cells of each type are aggregated to serve specific function. Such a group of cells is called a tissue.

.There are four main type of tissues: epithelial , muscular , connective and nervous. Some or all of these types of tissues may occur in an animal.

.In more complex animals, groups of organs work together for a common goal.

BODY SYMMETRY

.Body symmetry is the similarity of parts in different regions and directions of the body.

.When the body is not divisible into equal halves by any plane it is called asymmetrical or asymmetric as found in Amoeba and some sponges.

An animal is said to be symmetrical if its body is divisible into equal halves by one or more planes.

.Three types is said to be symmetrical if its body is divisible into equal halves by one or more planes.

.Three types of symmetry are usually seen in the animals.

SPHERICAL SYMMETRY

.It is found in animal whose body has the shape of a sphere.

.All planes that pass through the centre will cut it into similar haves e.g. Volvox, some sponges and some corals.

RADIAL SYMMETRY

.In this type of symmetry , the body can be divided into equal halves by any plane passing through the centre from top to bottom.

.In the animal kingdom, radially symmetrical phyla are porifera, coelenterata, ctenophore and echinodermata.

BIRADIAL SYMMETRY

.It is a variant form of radial symmetry found in ctenophora and most anthozoa (e.g., anemones), and is best fitted for a floating life.

.Such symmetry has only two pairs of symmetry found in ctenophora and most anthozoa (e.g. anemones) and is best fitted for a floating life.

.Such symmetry has only two pairs of symmetrical sides. There are only 2 planes of symmetry , one through the longitudinal and sagital axis, and the other through the longitudinal and transverse axis, which will divide the animal into equal halves.

BILATERAL SYMMETRY

.In most higher animals, the longitudinal axis of body runs from the anterior end(head) to the posterior end (tail).

.There is a single plane, the median longitudinal or sagital plane, through which the body can be divided into two similar right and left halves. This is called bilateral symmetry.

.First phylum of Animal Kingdom to exhibit bilateral symmetry is the phylum platyhelminthes. It is also present in phyla Aschelminthes, Annelida, Mollusca, Arthropoda, Echinodermata, Hemichordata and Chordata.

GERMINAL LAYERS

.The germinal or germ layers of cells differentiate in the animal embryos at the gastrulation stage. The germinal layers give rise to all the tissues/organs of the fully formed individual.

.The embryo of poriferans and coelenterates have two germinal layers, the ectoderm and endoderm. These animals are called diploblastic.

.An undifferentiated layer, mesogloea , is present in between the ectoderm and endoderm.

.The embryos of all other animals (from phylum platyhelminthes to phylum chordata) have three germinal layers – the ectoderm, mesoderm and endoderm. These animals are called triploblastic animals.

SEGMENTATION

.Segmentation is division of differentiation of the body into distinct portions called segments. It is of two types: metameric segmentation and pseudometamerism.

METAMERIC SEGMENTATION (TRUE SEGMENTATION)

.Metameric segmentation is a type of segmentation where external divisions correspond to internal divisions.

.It occurs in three highly organized phyla-annelida, arthropoda and chordates.

.The occurs in three highly organized phyla-annelida, arthropoda and chordates.

.The body is often divided both externally and internally into a number of segments (metameres) e.g., annelids.

.Segmentation is mostly external in arthropods and mainly internal in man and other chordates.

.It is of two types, complete and incomplete metamerism.

COMPLETE METAMERISM

.Affects practically all the systems and all the metameres are essentially alike or homonomous. This condition is also called homonomous metamerism and is seen in annelid worms.

INCOMPLETE METAMERISM

.The segments or metameres of different regions of the body become greatly dissimilar due to division of labour. This is seen in higher organisms like arthropods and vertebrates. This condition is also called as heteronomous metamerism.

PSEUDOMETAMERISM ( FALSE SEGMENTATION)

.It is found in tapeworm. The proglottids ( segments of tapeworms) are budded off from the neck and are not of embryonic origin hence, this segmentation is called pseudometamerism ( pseudosegmentation).

.Pseudosegmentation as found in tapeworms is external only. The body is not internally divided.

BODY CAVITY OR COELOM

.A body cavity can mean any internal space, or a series of spaces present inside body. Whereas coelom or true body cavity generally refers to a large fluid-filled space (cavity) lying between the outer body wall and the inner digestive tube.

.The animals which do not have coelom are called acoelomates e.g. , sponges, cnidarians , ctenophores and flat worms.

.The animals which have body cavity, called pseudocoel, derived from blastocoels of the embryo are called pseudocoelomates. Round worms are pseudocoelomates.

.The animals which possess true coelom are called eucoelomates of coelomates.

.The true coelom is a body cavity which arises as a cavity in embryonic mesoderm.

.In this case, the mesoderm of the embryo provides a cellular lining, called coelomic epithelium or peritoneum, to the cavity.

.The coelom is filled with coelom fluid secreted by the peritoneum.

.True coelom is found in annelids , echinoderms and chordates.

.True coelom is two types: schizocoelom (schizocoel) and enterocoelom (enterocoel).

.Schizocoelom: It is develops as a split in the mesoderm sheet. It is found in annelids, arthropods, molluscs.

.Enterocoelom: The mesoderm arises from the wall of the embryonic gut or enteron as hollow outgrowths which form this type of coelom. It occurs in echinoderms and chordates.

.The cavity filled with blood is called haemocoel. It is found in arthropods and molluscs.

CEPHALIZATION

.Differentiation of a definite head at the anterior end is termed the cephalization.

.There is a concentration of sense organs, nervous tissue (brain) and food catching organs at the anterior end.

SEXUAL DIMORPHISM

.When the male and female animals can be distinguished externally, the condition is called sexual dimorphism. The later is seen in peacocks and peahen, lion and lioness, and human being.

.Most of the animals have sex organs for sexual reproduction.

.The sexes are also separate as male and females. These animals with separate sexes are called unisexual or dioecious animals.

.In some lower animals such as flatworms and earthworms, the organs of both the sexes are found in the same individual. These are called bisexual or monoecious or hermaphrodite.

.In them, testes and ovaries do not mature simultaneously.

.In some, e.g., earthworm, testes mature earlier and the condition is called protandry and in some like sea-squirt ovaries mature earlier and the condition is known as protogyny.

FERTILIZATION

.Fertilization is the union of zygotes.

.In animals, male gametes or sperms are motile. The female gametes or ova are nonmotile.

.When fertilization occurs outside the body of the female, it is called external fertilization, e.g. star fish, frog.

.In many cases, fertilization takes place in the genital tract of the female. It is known as internal fertilization, e.g., reptiles, birds and mammals.

.When the fusion of male and female gametes of same parent takes place it is called self-fertilization, e.g. tapeworm.

.When the fusion of male and female gametes of different parents take place, it is known as cross-fertilization, e.g., all fishes, amphibians, reptiles, birds and mammals.

.The animals which have internal fertilization may give birth to young ones. They are of two types: ovoviviparous and viviparous.

.The former produce large, heavily yolky eggs that develop in the reproductive tract of the mother, without deriving nourishment from her, e.g., sharks, rattle snake.

.The viviparous animals produce minute eggs and the embryos are nourished during development in the mother’s genital tract, e.g. mammals.

.All the animals with external fertilization, as also many with internal fertilization, lay eggs. They are called oviparous.

DEVELOPMENT

.Development includes changes that an organism undergoes from its beginning to maturity.

.It is of two types, direct and indirect.

.In direct development, the young ones resemble the adults in all respects except colour , size.

.There is no intermediate stage in direct development, e.g., Hydra, earthworm and silver fish (insect).

.In indirect development, the young ones do not resemble the adults.

.The young ones usually pass through one or more intermediate stage before obtaining the shape of the adults.

.The phenomenon of passing through different juvenile stages before attaining the form of adult is known as metamorphosis, e.g., silk moth.

BODY TEMPERATURE

.In most of the animals, the body temperature is not fixed and varies with that of the environment. Such animals are called poikilothermic or ectothermic animals.

.In birds and mammals, the body temperature remains constant irrespective of the environmental temperature. They are termed homoeothermic or endothermic animals.

DIGESTIVE TRACT

.Digestive tract is the passage where food is taken, for digestion, absorption and elimination of undigested food.

.Coelenterates and flatworms have a digestive tract with a single termed mouth that takes food as well as eliminates the undigested food.

.This type of digestive tract is called incomplete.

.Digestive tract of many animals has two openings, mouth for intake of food and anus for the elimination of faecal matter.

.Such a digestive tract is termed complete. It is found from round worms to mammals.

HETEROTROPHIC MODE OF NUTRITION

.Plants synthesize their own food and hence are called autotrophs. Because animals feed upon other living forms, they are called heterotrophs.

.Heterotrophs are of following type:

i)Herbivores: eat plants.

ii)Carnivores: eat animals.

iii)Omnivores: eat both animals and plants.

.Some animals depend on other organisms for food, these are called parasites.

CIRCULATORY SYSTEM

.It is a system that takes part in continuous flow of blood in the body. Circulatory system is of two types, closed and open.

.In closed type circulatory system, the blood circulates inside the blood vessels without ever coming in direct contact with the body cells, e.g., annelids, chordates.

.In open type circulatory system, the blood flows in open space like lacunae and sinuses. It bathes the cell directly, e.g., arthropods, molluscs.

.Blood may be colorless (e.g., insects), bluish due to a respiratory pigment haemocyanin (e.g., prawn, pila) or red due to respiratory pigment, the haemoglobin (e.g., earthworm, vertebrates).

.Certain animals like Taenia, do not have circulatory system.

RESPIRATION

.Aerobic animals utilize oxygen which is obtained from air or water.

.Certain aquatic animals like Hydra take oxygen and give up carbon dioxide through body surface. This is termed body surface respiration.

.Many animals such as prawn and fish have gills for exchange of gases. This type of respiration is called branchial respiration.

.In earthworm, leech, frog, etc., exchange of gases takes place through skin, thus is termed as cutaneous respiration.

.In arachnids (e.g., spiders) exchanges of gases takes place through book like structures, the book-lungs.

.Book gills are respiratory organs in king crabs.

.Lungs are meant for exchange of gases in many animals (all amphibians, reptiles, birds and mammals). This type of respiration is termed pulmonary respiration.

.Anaerobic respiration occurs in various parasitic animals in which there is no utilization of oxygen.

EXCRETION

.Excretion is the removal of the metabolic wastes from the body.

.Sponges, coelenterates and echinoderms lose metabolic wastes by diffusion through body surface.

.Many animals have definite excretory structures. The flat worms have flame cells as excretory structure.

.Annelids have nephridia as excretory organs.

.Insects and some other arthropods have Malpighian tubules as excretory organs.

.Molluscs and vertebrates have have kidneys as excretory organs.

.Excretory organs not only remove metabolic wastes but also maintain water and salt content in the body (osmoregulation).

.Animals are classified as follows on the basis of the removal of nitrogenous wastes.

—Ammonotelic animals: They excretes ammonia. Examples: protozoans (e.g., Amoeba, Paramecium), sponges (e.g., Sycon), cnidarians or coelenterates (e.g., Hydra), liver fluke, tapeworm, Ascaris, Nereis, earthworm, leech, prawn, Pila, bony fish (e.g., Labeo), amphibian tadpoles, tailed amphibians (e.g., salamanders), crocodiles.

—Ureotelic animals: They excrete urea. Examples: cartilaginous fishes (e.g., sharks and rays), semiaquatic amphibians (e.g., frog and toads), turtles, alligators, mammals including man. Ascaris and earthworm are both ammonotelic and ureotelic.

—Uricotelic animals: They excretes uric acid. Examples: Most insects, some land crustaceans (e.g., Oniscus – commonly known as wood louse), land snails (e.g., Helix – commonly called “sand snail”), land reptiles (lizards and snakes ) and birds.

NERVOUS SYSTEM

.Nervous system is a system of neurons (nerve cells) that take part in conduction of impulse and coordination of body activities.

.Sponges do not possess nervous system.

.The coelenterates have network of nerve cells that form primitive type of “nervous system”.

.In flat worms and round worms the nervous system consists of nerve ring around the anterior part of the alimentary canal and many nerve cords.

.In annelids and arthropods it comprises a nerve ring around the anterior part of the alimentary canal and many nerve cords.

.In molluscs, the nervous system consists of ganglia, commissures and connectives.

.In echinoderms there are usually present oral and aboral nerve ring and radial nerves.

.Chordates have dorsally placed hollow nervous system.

SKELETON

.Hard external or internal structure of animal body constitute the skeleton. Many coelenterates, all flat worms, round worms and annelids lack hard support and have a soft body. Outer animals contain a skeleton.

.Exoskeleton lies outside the body of an animal and is made up of nonliving materials.

.Example of exoskeleton are chitinous cuticle of arthropods, calcareous shell of molluscs, and scales, feathers, hair, horns, hoofs, claws, nails and hair of vertebrates.

.Endoskeleton lies entirely within the body of the animal.

.In vertebrates such as sponges it is made up of calcareous and siliceous spicules.

.In some echinoderms hard plates are found under the skin.

.Skull of frog and Rabbit is dicondylic.

.Vertebral formula of Rabbit is (C7Th12-13L6.7S4cd16).

PROTOZOAN PROTISTS

.Protozoans were first studied by Leeuwenhoek (1677). The name “Protozoa” was coined by Georg August Goldfuss (1817). The branch of biology which deals with protozoa is called protozoology. There are about 15000 species of protozoans.

Occurence

.Protozoans may be aquatic (fresh water or marine), terrestrial , free-living or parasitic forms cause disease in human and animals.

Structure

.They are small, microscopic, acellular organisms with varied forms. The term acellular is used because the whole body consists of a single functional unit which performs as an organized body not as a cell. The body may be covered by a delicate membrane or firm pellicle or calcareous or siliceous shell. They show radial or bilateral symmetry. Protozoans have molecular or protoplasmic level of body organization. One to several nuclei are present in protozoans. One or more contractile vacuoles are present for osmoregulation.

Locomotion

.They move by means of pseudopodia, cilia or flagella. Major group of protozoans based on locomotary organs are:

—Zooflagellata (Flagellated protozoans) eg. Leishmania

—Sarcodina (Amoeboid protozoans) eg. Amoeba

—Ciliate (Ciliated protozoans) eg. Paramecium

—Sporozoa (no means of movement in adults ) eg. Plasmodium

Nutrition

.The mode of nutrition is mainly holozoic. Some forms are saprobic or parasitic. Their reserve food is glycogen.

Reproduction

.Asexual reproduction occurs mainly by binary fission, budding, multiple fission. some species reproduce sexually undergoing conjugation or syngamy.

Other features

.Protozoans perennate in unfavorable weather by cyst formation. Cyst has hard covering so can withstand unfavorable conditions. When conditions turn favorable individual emerges out from cyst and lives active life.

.Study of protozoans is very important for man as many of them are parasites over man and other organisms.

.Example of some very common protozoan parasites are given below.

i)Trypanosoma gambiense which causes sleeping sickness and is transmitted by tse-tse fly.

ii)Leishmania donovani which causes kala-azar and is transmitted by sand fly.

iii)Giardia intestinalis occurs in upper part of huma intestine. It causes giardiasis.

iv)Trichomonas vaginalis causes leucorrohoea in women.

v)Plasmodium vivax causes malaria. Female Anopheles mosquito acts as a transmitter.

vi)Trophozoite is adult and feeding stage of malaria parasite.

vii)Sporozoite is infective stage of malarial parasite.

viii)Entamoeba histolytica causes amoebiasis or amoebic dysentry.

SLIME MOULDS

.The slime moulds cause the decay and decomposition of the organic matter in the soil.

.They creepy over the ornamental plants and make them look ugly.

.Their attractive colour are of artistic value.

.The plasmodia of slime moulds are an excellent material for the study of structure and physiology of protoplasm.

Protozoa.

Divided into subphylums on the basis of locomotory organelles

1. Sacromastigophora : Locomotory organelles are pseudopodia or flagella or both.
   • Zooflagellata :
     • They are protozoan which possess one to several flagella for locomotion. (e.g. Euglena, Trypanosoma etc.
     • Contractile vacuole is present for osmoregulation.
     • Classes
     • Phytomastigophora; with chloroplast, plant life e.g., Euglena, Chlamydomonas etc.
     • Zoomastigophora; without chloroplast, animal life e.g. , Trypanosoma, Leishmania, Giardia etc.
   • Sarcodina:
     • Body mostly amoeboid.
     • Locomotory organ is changeable due to presence of pseudopodia which bring about the temporary outpushing of cytoplasm.
     • Types of pseudopodia are
       • Lobopodia (Amoeba)
       • Filopodia (Euglypha)
       • Reticulopodia(Globigerina)
       • Axopodia(Actinophrys sol.)
   • Opalinata
     • Locomotory organ are flagella, cilia-like.
     • Gametes are flagellated involved in sexual reproduction e.g., Opalina.
2. Sporozoa
   • • Locomotory organelles and contractile vacuole are absent.
     • All memebers of these group are endoparasites. e.g., Plasmodium, Monocystits, Gregarina, Eimeria, Toxoplasma etc.
3. Cnidospora
   • • Intracellular endoparasites, especially of insects.
     • No locomotory organelles and contractile vacuole.
     • Classes, on the basis of spore formation.
     • Spores are large. Parasites mostly in fishes.
       • Myxosporidea: spores are large Parasites mostly in fishes (e.g., Myxidium).
       • Microsporidea: spores are small (e.g., Nosema)
4. Ciliata
   • • Largest group of protozoa.
     • Locomotory organelles are cilia or ciliary organelles which are replaced by sucking tentacles in adult.
     • Dimorphic ( 2 different types of nuclei: micro and macro nuclei).
     • Class: Ciliata (e.g., Paramecium, Balantidium)

ANIMAL KINGDOM

1. Phylum Mesozoa
   • e.g., Dicyema
     • No tissues, body comprising an external layer of ciliated cells.
     • Minute body, worm like.
     • No tissues, diploblastic , cellular level of body organization.
2. Branch Parazoa
   • Tissues or organ system level of body organization.
     • PHYLUM PORIFERA
       • Members commonly called sponges, marine and asymmetrical.
       • Presence of canal system, which helps in food gathering, respiratory exchange.
       • Body supported by skeleton made up of spicules or sponging fibres.
       • Choanocytes present.
       • Hermaphrodite, reproduction both sexual and asexual, fertilization internal, development indirect having larval stage.
       • E.g., Leucosolenia, Sycon, Euspongia (Bath sponge). Spongilla (Fresh water sponge).
3. Branch Eumetazoa
   • Division Radiata
     • Body radially symmetrical, diploblastic, tissue level of body organization.
   • Division Bilateria
     • Sub division – Acoelomata
       • True coelom
       • Coelom develops from solid mesoderm.
     • Sub division – Pseudocoelomata
     • Sub division – Eucoelomata

Phylum Cnidaria (=Coelenterata)

.Aquatic, mostly marine, sessile or free swimming animals.

.Cnidoblasts or cnidocytes present, which help in anchorage and defense.

.Central gastrovascular cavity with a single opening, mouth on hypostome.

.Posses two forms: polyp (sessile) and medusa (free swimming).

.Exhibit alternation of generation (metagenesis), i.e., polyps form medusa asexually and medusa form the polyps sexually.

.E.g. Hydra, Adamsia (sea anaemone). Obelia, Aurelia (Jelly fish), Physalia (Portuguese man-of-war), Pennatula(Sea-pen), Gorgonia(Sea-fan) and Meandrina (Brain coral).

Phylum Ctenophora

.Exclusive marine, commonly called sea walnuts or comb jellies.

Possess ciliated comb plates, which help in locomotion.

.Digestion both extracellular and intracellular.

.Bioluminescence is well marked.

.Sexes not separate, reproduction only by sexual means, fertilization external with indirect development.

.E.g., Pleurobrachia, Ctenoplana.

Division Bilateria

.Body bilaterally symmetrical , triploblastic, organ system of body organization.

Subdivision Acoelomata

.No coelom

Phylum Platyhelminthes

.Flatworms; mostly endoparasites; hooks and suckers present.

.Flame cells help in osmoregulation and excretion.

.Sexes are not separate; fertilization is internal; development through many larval stages.

.Some members like Planaria possess high regeneration capacity. E.g., Taenia (Tapeworm), Fasciola (Liver fluke).

Subdivision Pseudocoelomata

.Pseudocoelom (false coelom).

Phylum Aschelminthes

.Flatworms; mostly endoparasites; hooks and suckers present.

.Flame cells help in osmoregulation and excretion.

.Sexes are not separate; fertilization in internal; development through many larval stages.

.Some members like Planaria possess high regeneration capacity. E.g., Taenia (Tapeworm), Fasciola (Liver fluke).

Subdivision Pseudocoelomata

.Pseudocoelom (false coelom).

Phylum Aschelminthes

.Roundworms; may be free living, aquatic and terrestrial or parasitic.

.Alimentary canal complete with developed muscular pharynx; excretory tube removes body wastes.

.Sexes separate (dioecious ); female longer than male, fertilization internal; development may be direct (young one resemble the adult) or indirect.

.E.g., Ascaris (Roundworm). Wuchererria (Filarial worm), Ancylostoma (Hookworm).

Enterocoelomata

.Coelom develops from enteric pouches.

Phylum Echinodermata

.Possess endoskeleton of calcareous ossicles: all marine; adults radially symmetrical but larvae bilaterally symmetrical.

.Digestive system complete.

.Presence of water vascular system which helps in locomotion, capture and transport of food and respiration; excretory system absent.

.Sexes separate: reproduction sexual; fertilization external: development indirect with free-swimming larva.

.E.g. Asterias (Star fish), Echinus (Sea urchin), Antedon (Sea lily), Cucumaria (Sea cucumber ) and Ophiura (Brittle star).

Phulum Annelida

.Aquatic (marine or freshwater) or terrestrial; metamerically segmented.

.Body surface distinctly marked or metameres; possess longitudinal and circular muscles (for locomotion).

.Possess parapodia (swimming); nephridia (excretion): neural system (ganglia); closed circulatory system.

.Both dioecious (Nereis) and monoecirous (Earthworm and leeches); reproduction sexual.

.E.g, Nereis, Pheretima (Earthworm) and Hirudinaria (Blood sucking leech)

Phylum Mollusca

.Second largest phylum; terrestrial or aquatic (marine or fresh water).

.Body covered by calcareous shell, unsegmented with distinct head, muscular foot and visceral hump.

.Posses mantle, feather like gills in mantle cavity(for respiration and excretion); sensory tentacles; radula (rasping organs).

.Usually dioecious and oviparous with indirect development.

.E.g., Pila (Apple snail), Pinctada (Pearl oyster), Sepia (Cuttle fish), Loligo (Squid). Octopus (Devil fish), Aplysia (Sea-hare), Dentalium (Tusk shell) and Chaetopleura (Chiton).

Phylum Arthropoda

.Largest phylum (insect); body covered by chitinous exoskeleton.

.Body consists of head, thorax and abdomen possess jointed appendages.

.Possess gills, books gills, book lungs or tracheal system (respiratory organs): circulatory system open; sensory organs like antennae, eyes (compound and simple). Statocysts or balance organ present; excretion through malpighian tubules.

.Mostly dioecious ; fertilization usually internal; mostly oviparous; development may be direct or indirect.

.E.g., Apis (Honey bee). Bombyx (Sik worm), Laccifer (Lac Insect). Anopheles, Culex and Aedes (Mosquitoes), Limulus – Living fossil (King crab).

Section Agnatha

.Jawless vertebrates

Class Ostracodermi

.All fossils.

.Body was fish-like: bony armour for survival.

.Remote ancestor of all vertebrates.

.E.g. Cephalaspis, Hemicyclaspis.

Class Cyclosomata

.All ectoparasites on some fishes.

.6-15 pairs of gill slits for respiration; sucking and circular mouth; body devoid of scales and paired fins.

.Marine but migrate to freshwater for spawning, larvae after metamorphosis return to ocean.

.E.g. Petromyzon (Lamprey), Myxine(Hag fish).

Section Gnathostomata

.Jawed vertebrates

Phylum Hemichordata

.Earlier considered as a subphylum under phylum chordata, but now placed as a separate phylum under non-chordata.

.Worm-like marine animals ; body cylindrical , composed of proboscis, collar and trunk.

.Open circulatory system; respiration through gills; excretion by proboscis gland.

.Sexes separate; fertilization external; development indirect.

.E.g. Balamoglossus and Saccoglossus.

Phylum Chordata

.Presence of notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits.

.Possess post and tail and a closed circulatory system.

Subphylum Urochordata

.Notochord present only in larval tail.

.Marine; body covered by test or tunic.

Retrogressive metamorphosis.

.E.g. Ascidia, Salpa, Doliolum, Herdmania.

Subphylum Cephalochordata

.Notochord extends from head to tail and is persistent throughout life.

.E.g. Branchiostoma (Amphioxus or Lancelet.)

Subphylum Vertebrata

.Notochord present during embryonic period while in adult replaced by cartilaginous or bony vertebral column.

.Vertebral muscular heart with two, three or four chamber; kidneys for excretion and osmoregulation: paired appendages which be fins or limbs.

Class Chondrichthyes

.Marine animals with streamlined body; cartilaginous endoskeleton; mouth located ventrally; notochord persistent throughout life; gill-slits without operculum.

.Skin tough with placoid scales; teeth are modified placoid scales.

.Animals predacious; air bladder absent; heart 2 chambered; poikilothermous.

.Some have electric organs (Torpedo) and some have poison sting (Trygon).

.Sexes separate, internal fertilization; many are viviparous,

.E.g. Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray).

Class Osteichthyes

.Both marine and fresh water with bony endoskeleton.

.Body streamlined; mouth terminal; gills 4 paired covered by operculum; skin covered with cycloid/ctenoid scales.

.Air bladder present; heart 2 chambered; poikilothermous.

.Sexes separate; external fertilization; mostly oviparous and development is direct.

.E.g. Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater- labeo (Rohu), Catla (Katala), Clarias (Magur): Aquarium-Betta (Fighting fish), Pterophyllum (Angel fish).

Superclass Pisces

.True fishes

Class Placodermi

.All fossils.

.Had protective body scales or plates.

.E.g. Climatius

Class Amphibia

.Can live in aquatic as well as terrestrial habitats; two pairs of limbs; cold-blooded animals. Body divided into head and trunk; skin moist without scales; eyes with eyelid; tympanum represents ear. Alimentary canal, urinary and reproductive ducts open into cloaca; respiration by gills, lungs and through skin; heart 3 chambered (2 auricles and 1 ventricles). Sexes separate; fertilization external; oviparous and development is indirect. E.g. Bufo (Toad), Rana(frog), Hyla (Tree frog), Salamandra (Salamander), Ichthyophis (Limbless amphibian).

Class Reptilia

.Mostly terrestrial; crawling and creeping animals; poikilotherms. Body covered by dry and cornified skin, epidermal scales or scutes; don’t have external ear opening; tympanum represents ear. Limbs when present, are two pairs; heart ususally 3 chambered (4-chambered in crocodiles). Sexes separate; fertilization internal, oviparous and development is direct, E.g. Chelone (Turtle), Testudo (Tortoise), Chamabeleon (Tree lizard). Calotes (Garden lizard), Crocodilus (Crocodile). Alligator (Alligator). Hemidactylus (Wall lizard). Poisonous snakes. Naja (Cobra), Bungarus (Krait), Vipere (Viper).

Class Aves

.Presence of feathers; most of them can fly except flightless birds (Ostrich). Possess beak; forelimbs modified into wings; hindlimbs (generally have scales) modified for walking, swimming or clasping. Skin dry without glands except oil glands at base of tail; fully ossified (bony) endoskeleton; pneumatic (air cavities) bone. Digestive tract possesses crop and gizzard; heart completely 4-chambered; warm-blooded (homoiothermous) animals; respiration by lungs (air sacs connected to lungs). Sexes separate: fertilization internal; oviparous and development direct E.g. Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich). Pavo (Peacock). Aptenodytes (Penguin), Neophron (Vulture).

Class Mammalia

.Found in variety of habitats (polar ice caps , deserts, mountains, forests, grasslands and dark covers; some fly and some live in water). Presence of mammary glands. Limbs 2 pairs adapted for walking, running, climbing, burrowing. Swimming or flying. Skin possess hair; external ear or pinnae present; teeth of different type; heart 4-chambered; homoiothermous animals; respiration by lungs. Sexes separate; fertilization internal, viviparous (few exception) and development direct. E.g. Oviviparous – Ornithorhynchus (Platypus) ; Viviparous. Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel)., Macaca (Monkey) , Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse) , Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Pantheral leo (Lion)