BIOLOGY CLASS NOTES FOR CBSE Chapter 04. Animal Kingdom 01. Basis of Classification Level of body organization : Protoplasmic level ↓
→ In protozoans, acellular body performs all biological activities.
Cellular level
→
In sponges, cells are arranged as loose call aggregates and division of labour occurs among cells (Tissues absent).
→
In coelenterates and ctenophores, cells performing the same function are arranged into tissues.
→
In platyhelminthes and other higher phyla tissues are grouped together to form organs.
↓ Tissue level ↓ Organ level ↓ Organ system level
In higher animals, organs further organise to form organ systems → e.g. Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Chordata.
Symmetry: 1) Asymmetry :- When any plane that passes through the centre does not divide the body of animals into two equal halves. e.g. : most of sponges are asymmetric. 2) Radial symmetry : When any plane passing through the central axis of the body divide the animal into two identical halves. e.g. : Coelenterates, ctenophores and echinoderms (adult) 3) Billateral symmetry : When the body can be divided into identical left & right halves in only one plane. e.g. : Platyhelminthes to chordates.
Germinal layers :(a) Diploblastic : Animals in which the cells are arranged in two embryonic layers ectoderm and endo-derm with an interveining undifferentiated mesoglea e.g. Sponges, Coelenterates and Ctenophores. (b) Triploblastic : Those animals in which the developing embryo has a third germinal layers Mesoderm in between the ectoderm and endoderm e.g. Platyhelminthes to chordates.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
Body Cavity or Coelom : Presence or absence of a cavity between the body wall and gut wall is very important in classification. (a) Acoelomates : Animals in which the body cavity is absent e.g. Platyhelminthes (b) Pseudocoelomates : Animals in which body cavity is not lined by mesoderm, instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom. e.g. Aschelminthes. (c) Coelomates : Animals possessing coelom i.e. the body cavity which is lined by mesoderm on all sides On the basis of embyonic development, the coelom is of two types. (i) Schizocoel : Coelom formed by splitting of a mesodermal mass e.g. Annelida, Arthropoda, Mollusca. (ii) Enterocoel : Coelom formed by fusion of gut pouches during embryonic stage e.g. Echinodermata, Hemichordata and Chordata.
Body plan : (a) Cell-aggregate type : e.g. Sponges (b) Bling Sac type : Animals in which digestive system in incomplete, it has only single opening to the outside of the body that serves as both mouth and anus. e.g. Coelenterates to Platyhelminthes (c) Tube-within-tube type : Found in those animals having complete digestive tract i.e. with separate openings mouth and anus. e.g. Nemathelminthes to chordates
Segmentation : (a) Pseudometameric : e.g. Tapeworms (b) Metameric : In Annelids, arthropods and chordates. In these animals, the body is externally and internally divided into segments with a serial repetition of atleast some organs, this is called metameric segmentation and the phenomenon is known as Metamerism.
Notochord : It is a mesodermally derived rod-like structure formed on the dorsal side during embryonic development in some animals. (a) Non-chordates : Animals without notochord e.g. Porifera to hemichordata (b) Chordates : Animals with notochord.
Circulatory system : (a) Open type : In which the blood remain filled in tissue spaces due to absence of blood capillaries. e.g. Arthropods, Molluscs, Echinoderms, Hemichordates and some lower chordates like tunicates. (b) Closed type : In which the blood is circulated through a series of vessels of verying diamters i.e. arteries, veins and blood capillaries e.g.Annelids, Cephalopod molluscs, Vertabrates etc.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
Embryonic development : On the basis of fate of blastopore, animals can be divided into two categories : (a) Protostomiates : Animals in which mouths is formed first (Blastopore → Mouth) e.g. Platyhelminthes to Mollusca (b) Deuterostomiate : Animals in which anus is formed earlier than mouth (Blastopore → Anus) e.g. Echinoderms, Hemichordates and Chordates. Animals (level of organization)
Protozoa
Matazoa
(Protoplasmic level)
(Cellular / tissue / organ level)
Parazoa
Eumetazoa/Enterozoa Tissue and organ system Division (Symmetry)
Bilateria
Radiata Diploblastic Tissue level
Triploblastic Organ system level
(i) Coelenterata-Hydra (ii) Ctenophora
Sub Division
Deuterostomous
Protostomous
Eucoelomata Acoelomata
e.g. Platyhelminthes
Pseudocoelomata
Nemathelminthes (Nematoda)
Schizocoel
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Eucoelomata
Enterocoel
Annelida Mollusca Arthropoda
Echinodermata Hemichordata Chordata
Haemocoel
CLASS NOTES FOR CBSE – 04. Animal Kingdom
02. Phylum – Protozoa Ÿ Ÿ Ÿ
Ÿ Ÿ
Ÿ
Ÿ Ÿ
Ÿ
Ÿ
Ÿ
It is 3rd largest phylum. One called performance all the biological activities like multicellular animals. So They are termed as “Acellular” organism, proposed by Dobell. Protozoans were first studied by Leeuwenhoeck. And the name Protozoa was coined by Goldfoss Study of protozons is the know as Protozoology. They are world wide, Cosmopolitan and mostly Microscopic, Aquatic, Terrestrial, free living (Amoeba) or parasitic (Plasmodium). Solitary or colonial (Proterospongia). Many causes serious diseases or pathogenic. Protozoans are small microscopic, Eukaryotic Unicellular, Colourless, Spherical, Oval, Bell shaped, Spindle shaped slipper like having irregular symmetry. Level of body organization of Protozoans is Protoplasmic level. Consists of uninucleate or multinucleate protoplasm mostly nacked or have body bounded by delicate membrane or a firm Pellicle/Test/Lorica/shell. In few groups of protozoa & Silica shell (in some marine amoebic form) as exoskeleton is found. e.g. Radiolarian group & Foraminiferan group. Number of nuclei vary from one to many. Few show nuclear dimorphism. e.g. Paramoecium. Body perforce all necessary biological activity so in them subcellular – Physiological division of labour is found. Locomotion by means of (i) Finger-like Pseudopodia e.g. Amoeba(Class – Sarcodina) (ii) Whip like Flagella e.g. Eulena(Class – Flagellata) (iii) Hair cillia e.g. Paramoecium (Class – Ciliata) (iv) No locomotory organelles e.g. Plasmodium (class _ Sporozoa) Nutrition of Protozons are mainly holozoic (Amoeba), Mixotrophic. (Euglena), Parasitic, Saprozoic (Plasmodium) and Digestion is intercellular take place in food vacuole. Respiration and Extraction takes place by the exchange of gases through body surface. Some excretion may occur through contractile vacuole. Nitrogenous waste is Ammonia. Some fresh water Protozoans get rid of excess water through contractile vacuole and phenomenon know as Osmoregulation. Amoeba has one and Paramoecium has two vacuoles. Reproduction takes place by Asexual Sexual (i) Binary Fission (Amoeba) (i) Syngamy (Plasmodium) (ii) Transverse Fission (Paramoecium) (iii) Conjunction (Paramoecium) (iv) Longitudinal fission (Trypansoma, Euglena) (v) Multiple fission (plasmodium) (vi) Budding Some also form cyst which help in unfavorable condition for production of organism. They do not have natural – death because in unicellular animals there is no division of somatoplasm & germplasm. So these are considered as immortal.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
03. Phylum – Porifera Ÿ Ÿ Ÿ Ÿ
Robert Grant gave the name Porifera. Study of sponges is known as Parazoology. Phylogenetically evolved from choano flagillates (Proterospongia). Mostly marine but few are found in fresh water also. They are sessile, solitary or colonial. Entire body with pores i.e. numerous mouthlets Ostia and one opening for exit Osculum. Ÿ Sponge have various body form and shapes i.e. Vase shape, cylindrical with radial symmetry (Leucosolenia), mostly irregular shape (asymmetrical). Ÿ Sponge have cellular level of organization with two germ layer i.e. Diploblastic and do not posses head and appendages Ÿ Body wall consists of (i) Outer Dermal Layer Or Pinacoderm (a) Pinococytes (Flat cell) (b) Porocytes (oval) In case of Sycon pinacoderm is divided into exopinacoderm and endopinacoderm. Endopinacoderm lines the incurrent canal. (ii) Inner Choanocytic layer or Choanoderm / Gastral Layer Collar cell or Choanocytes (Flagellated) − Characteristic of Porifera − Choanocytes discovered by – H.J. Clark (iii) Between these two layer gelation material Mesenchyme (Mesophyl) is present which is non-cellular. It Consist of Amoebacytes = gives rise to different types of cells both pinacoderm and Choanoderm.
Amoebocytes
Scleroblast Spongioblast Thesocytes Phagocytes Trophocytes
− − − − −
Archaeocytes
−
Collenocytes Chromocytes Myocytes Gland cells
− − − −
Germ cells (sex cells)
−
Ÿ
For skeleton For skeleton For food storage (Glycogen) To engulf by phagocytosis For Distribution of food Formation Ova & Spermatozoa (Totipotant cells) Connective tissue cell Pigmented Highly shiny substance Secrete shiny substance Form sperm & ova during breeding season.
Body Well enclose a large cavity the spongocoel or paragastric cavity. Chanocytes with flagella is lined in Spongocoel and radial canal. Ceaseless beating of flagella cause current of water which enter through ostia perforating porocytes and various canals and enters in spongocoel and finally leave through large aperature osculum. Ÿ Canal system: Canal system of porifera helps in nutrition, respiration, excretion and reproduction Canal are developed due to folding of inner wall. there are four types of canal systems.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
(i)
Asconoid (Simplest canal) Ingressing water Canal Ex. Leucosolenia, Olynthus
(ii)
Spongocoel
Osulum
Syconoid Ingressing water
dermal ostia
incurrent canals
prosopyles
radial canals apopyles
to outside
osculum
spongocoel
Ex. Scypha (iii) Leuconoid
(complex and most efficient canal system) Ingressing water
dermal ostia
incurrent canals
prosopyles
flagellated chambers apopyles
to outside
Ÿ
Ÿ Ÿ Ÿ
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excurrent canals
Ex. Euspongia, Spongilla (In Spongilla the leuconoid condition is derived from a larval stage called the rhagon) Skeleton is internal, consist of tiny calcarious Spicules (calcoblast) or siliceous spicules (silicoblast) or fine spongin fibre (Spongioblast), or of both located in mesenchyme. There are four types of spicules in sponges (i) (ii)
Ÿ
osculum
Monaxon (Usually at osculum) Triaxon
(iii) Tetraxon (iv) Polhyaxon [Hexa – radiated]
Scleroblast secrets spicules and Spongioblast secrets spongin fibre Digestive cavity and mouth is absent. Nutrition is holozoic. Digestion is intracellular and occurs in food vacuoles of choanocytes. Food particles is taken by collar cell and pass them to amoebocyte. Food is stored in thesocytes. Distribution of food from ingestive cell to other is brought about by the movable amoebid cell. Trophocytes. Respiration and Excretion takes place by diffusion of gases through body surface. Excretory matter is Ammonia. Sponges do not have nervous system. (Parazoan character) Reproduction takes place by the means of (i) Asexual By Fragemetation, Regeneration in sponges was demonstrated by Wilson. It is brought about by archacocytes. By Budding – Special cell mass Gemmules containing Archaeocytes. Also called as Endogenous budding and the process is the know as Gemmulation.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
(ii)
Sexual Sponges are Hermaphrodite, fertilization internal and cross fertilization, Protogynous condition is found.
Formation of ova & spermatozoa (From Archaeocytes)
Fertilization – Internal, takes place in another sponge through water current
Zygote
Cleavage – Equal and Holoblastic Segmentation
Sponge ⇒ ⇒ ⇒ ⇒
Free living larva escapes from osculum
Larva (1) Amphiblastula hollow larva (scypha) Parenchymula Solid larva (Leucosolenia) (2) Stereogastrula (Euplectella)
Proterospongia = connective link between Protozoa-Porifera Largest Sponge – Spheciospongia Hypothetical simple sponge & between larva & sponge – Olynthus Shrimps – (also called as Spongicola fish) A crustacean, shows commensalisms with Euplectella
04. Phylum – Coelenterate (Cnidaria) Phylum cnidaria includes about 9,000 species. General characteristic features of animals of Phylum – Cnidaria (i) Habitat: The animals of this phylum are called coelenterates or cnidarians. They posses aquatic habitat as they inhabits the water bodies. Like sponges, they are also (e.g. Hydra) (ii) Habit: on the basis weather the animal live singly or in association of other, the coelenterates can be
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
(iii)
(iv)
(v)
(vi)
(vii)
(i) Solitary or (ii) Colonial. Those animals which live singly and are independent, without association of other individuals os the same type are called solitary animals e.g., Hydra. Those animals which live in the association of other individuals of the same type are called colonial animals. These animals which live in colony become dependent upon each other for fulfilling their needs like nutrition and for protection. e.g., Physalia, Gorgonia, Obelia On the basis of weather the animals remains attached to some solid support or substratum in the water or not, the coelenterates can be either (i) Sessile or (ii) Free-swimming or free-floating. Sessile animals remain attached to the under water substratum and free-floating animals freely swim along with the flow of water and do not remain permanently attached with any support. For example, Physalia, Aurelia are the free-swimming coelenterates. Body symmetry: The coelenterates are the radially symmetrical animals as any plane passing through the central body axis divides these animals into two identical halves. Level of organization: First time in the animal kingdom, cells associated to form the tissue in coelenterates. Hence they exhibit the tissue level of organization. The tissues are arranged variously to perform the basic functions in their body. Germ layers: These are the diploblastic animals as cells in their embryonic stages are arranged in two layers, outer ectoderm, inner endoderm with an intervening gelatinous layer mesoglea. This mesoglea provides the jelly-like form to some coelenterates. Body wall in coelenterates: (with reference to hydra): They are diploblastic animals i.e., they are derived from two layers-ectoderm and endoderm. These germ layers form the epidermis and gastrodermis. (i) Epidermis : The various epidermal cells are : (a) Epidermis-muscular cells : Each cell has two functional parts, the outer epithelial part, extending to the body surface and the basal muscular part drawn out into two processes along the longitudinal axis of the body. The muscle processes contain a contractile fibril myoneme. (b) Glandulo-muscular cells : The epithelio-muscle cells, chiefly in the region of the pedal disc, are especially modified to secrete sticky material for attachment of animal to substratum. (c) Interstitial cells : They are totipotent cells which give rise to all the different cells of the body. (d) Sensory cells : They are scattered throughout the epidermis. They are most numerous on the tentacles, hypostome and basel disc. They receive and transmit impulses. (e) Nerve cells : They occur for the first time in coelenterates. They are present at the base of epithelio-muscle cells. They conduct impulses in all the directions.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
(f) Germ cells : They reman in restricted regions. They proliferate to form gonads. They are ectodermal in hydrozoa and endodermal in Scyphozoa and Anthozoa. (g) Cnidoblasts : Many of the interstitial cells of the epidermis become specialized to form the stinging cells, called the cnidoblasts. They migrate to the tenbtacles through the mesoglea by means of amoeboid movements. Projecting cnidoblasts act as organs for offence and defence. (ii) Gastrodermis : It is the inner layer of the body. The cells are of following types : (a) Endothelio-muscle or nutritive muscle cells : They help in contraction of the body and nutrition. (b) Endothelio-gland cells : They secrete digestive enzymes in coelenteron. In the region of hypostome and mouth are found mucous gland cells. Gland cells are absent in the tentacles and basal disc. (c) It also contains interstitial cells, sensory cells and nerve cells but no cnidoblasts. (viii) Alternation of generation means polyps alternate with medusae asexually and medusae form the polyps sexually. This is also termed as metagenesis. Polyps undergo budding (asexual reproduction) to give rise to medusae and medusae produce gametes, sperm and ova (sexual reproduction) to give rise to new polyps. Hydra : Some important characters of Hydra are : (i) Hydra flourishes well in cool, clean and stagnant water. (ii) Number of tentacles surrounding mouth in Hydra is 6-10. Tentacles of Hydra are hollow while that of obelia are solid. (iii) Food of Hydra is water fleas (Daphnia and Cyclops). Thus, it is carnivorous. It No free larval stage in development of Hydra. Hence, development is direct. (iv) Most species of Hydra are dioecious/unisexual.cannot digest starch. (v) Male Hydra bears 1-8 conical testes towards distal and whereas female Hydra bears 1-2 rounded ovaries towards proximal end of the body. (vi) Locomotion in Hydra occurs by looping, somersaulting, gliding, walking and floating etc. (vii) The body of coelenterates bear a central gastro-vascular cavity which opens to the outside through a single opening called mouth. Mouth is an aperture present on the hypostome. Hypostome is a conical elevation present on the free (non-attached) end of the body. Entry of food and exit of waste material takes place through this single opening mouth. The central cavity of the body is called gastro-vascular cavity because it helps in the digestion of food (referring gastro) as well as in the circulation of materials. Externally the body bears flexible structures called tentacles which are able to contract (or shorten) as well as elongate. The tentacles help in feeding, deeling and grasping of prey. (viii) Cnidoblasts or Cnidocytes : The name cnidaria is derived from one of the most characteristic cell of all coelenterates, the stinging cells called cnidoblasts or chidocytes. Cnidiblasts are used for anchorage, defence and for the capture of prey. (ix) Skeleton : Some of the cnidarians, e.g., corals have a hard skeleton composed of calcium carbonate (CaCO3).
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
05. Phylum – Ctenophora : F Ctenophora name was given by Eschescboltz. Commonly called “Sea-gooseberries” or “Comb-jellies” or “Sea-walnuts“. F Nematoblasts are absent, so they are also called “acnidaria” (Exception = Euchlora) F Exclusively marine and pelagic (float on sea surface) and show Bioluminescence. F Body is soft transparent jelly like having Biradial symmetry with tissue grade body organization. F Triploblastic, Mesoglea contains amoeboid mesodermal cells called Colloblast, Amoeboid cells and smooth muscle cell. F Locomotion takes place by the presence of 8 ciliary comb plates on the body surface. F Special sensory structure statocyst at the opposite end (absoral end) of the mouth is present. F Tentacles may be present or absent. When present, the number of tentacles are 2. They are solid and possess adhesive cells called as colloblasts (lasso cells) F Digestion is both extracellular and intracellular. These are carnivorous animals. F Resp. system, skeletal, circulatory & excretory system are absent. F All animal are Bisexual. Complex type of sexual reproduction is found. Metagensis is absent. F Development is of indirect type. Life cycle involves a free living Cydippid larval stage. F Asexual reproduction is absent. F Regeneration & paedogenesis is normally found. Ctenophora is divided into two classes on the basis of presence or absence of tentacles. (i) Tentaculata (Tentacles present) (ii) Nuda (Tentacles absent) Eg. *Pleurobrachia Beroe – Swimming eye of cat. Velamen Cestum - “Venus’s girdle” *Ctenoplane – Commensal with Alcyonium. Hormiphora Euchlora rubra – with cnidoblast (Exception)
06. Phylum – Platyhelminthes Introduction The animals of this phylum have a dorso-ventrally flattened body. Their upper (dorsal) and lower (ventral) body surfaces are flat and that’s why they are commonly called flatworms. General Characteristic Features of Platyhelminthes : (a) Habit and Habitat : These are mostly endoparasites as they live inside the body of other animals (called hosts); including human beings and thrive nutrition as well as shetter from them, Some flatworms are free living. Dugesia (Panaria) is a fresh water flatworm. (b) Body symmetry : These are bilaterally symmetrical animals.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
(c) Level of organization : They are the first animals to have reached the organ level of organization (d) Germ layers : Platyhelminthes are the triploblastic animals. (e) Coelom : Although they are the triploblastic animals bearing mesoderm but coelom (i.e., mesoderm-lined body cavity) is lacking din them. Hence flatworms are the acoelomate animals. (f) Exoskeleton and Endoskeleton are completely absent. However hooks, spines, suckers (in parasitic form), teeth or thorns may be present which act as adhesive organs. (g) Respiratory and circulatory systems are absent. (h) Digestive tract : Digestive system in platyhelminthes has only a single opening to the outside of the body, that serves both as mouth and anus and hence it is incomplete. Parasitic adaptations : Ÿ Hooks : Hooks are the adhesive structures which help the worm to attach to the internal body layers of host. Ÿ Suckers : These help in the adhesion as well as ingestion (of food). Ÿ Direct absorption of food through body surface : As they have a flat body so some of them are able to absorb the nutrients directly through body surface. Ÿ Thick tegument : The body is externally covered with a thick tegument, a protective layer that protects the parasitic worms from the digestive juices of host. (i) Excretion and osmoregulation : The removal of waste products of metabolism like ammonia and other non-useful materials is called excretion and the regulation of amount of fluid (water) in the body is called osmoregulation. Flame cells are the specialised cells of platyhelminthes which help in the excretion as well as osmoregulation. (ii) Nervous system is primitive : The main nervous system consists of a pair of cerebral ganglia or brain and one to three pairs of longitudinal nerve cords connected to each other by transverse commissures. This type of nervous system is called ladder like nervous system e.g., Planaria (Dugesia) (iii) Reproduction : The flatworms are hermaphrodite (monoecious) except Schistosoma. They mainly reproduce sexually by producing sperms and ova. However some forms reproduce asexually also. (iv) Fertilisation : The fertilisation is internal in flatworms. (v) Development : It is usually indirect. (vi) Regeneration : The ability of an organism to replace its lost or damaged or the ability to develop a complete and normal individual from a part of the body is called regeneration. Some flatworms possess a tremendous power of regeneration. Planaria. Iy shows a high regeneration power. Example
Taenia (Tapeworm), Fasciola (liver fluke)
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
07. Phylum Aschelminthes/Nemathelminthes Introduction The Aschelminthes are commonly called roundworms, because the body appears circular in the transverse cross-section. General characteristic features of Aschelminthes : (i) Habit and Habitat : They may be free-living or parasitic. They may be aquatic or terrestrial. Parasitic roundworms live in plants and animals (endoparasites). Ascaris, Wuchereria, etc. are common animal endoparasites. (ii) Body symmetry : Roundworms are bilaterally symmetrical. (iii) Level of organization : Aschelminthes have the organ-system level of organization. (iv) Germ layers : Roundworms are the triploblastic animals. (v) Coelom : Aschelminthes possess the pseudocoelom and hence called pseudocoelomates. The body cavity is present but is not lined by the mesoderm, instead the mesoderm is present as scattered pouches in between the ectoderm and endoderm. (vi) Digestive system : The digestive system is complete having two separate openings. The alimentary canal is a straight tube extending from mouth at one end to anus on other end of body. The roundworms have a well-developed muscular pharynx. (vii) Excretory system : An excretory tube is present in the body of roundworms, which removes the body waste through an excretory pore. This excretory tube collects the body waste form body cavity and removes it out through the pore. (viii) Reproductive system : Sexes are separate, i.e., aschelminthes are dioeccious (unisexual). Males and females are distinct externally. (ix) Fertilisation : Fertilisation is internal. (x) Development : Some develop through an intermediate larval stage and some directly (where young ones resemble the adult) without any larval stage. Hence both direct and indirect development are seen in roundworms. Example
Ascaris (Roundworm), Wuchereria (Filaria worm), Ancylostoma (Hookworm), Enterobius (Oxyuris), Dracunculus medinensis (Guinea worm), Rhabditis (Free living).
08. Phylum – Annelida The phylum annelida includes over 9,000 species of metamerically segmented animals with true coelom. General characteristic features of Annelida : F Habits and Habitats : The annelids may be aquatic (marine and fresh water) or terrestrial For e.g. Nereis is marine, Earthworm is terrestrial and Hirudinaria is a fresh water annelid. Most of the annelids are free-living and some are parasitic in nature e.g. Hirudinaria, the blood sucking leech is a common ectoparasite. F Common name : The annelids are commonly called the segmental worms. They are called so because of the presence of distinct segments in their body. F Body symmetry : The members of phylum Annelida exhibit the bilateral symmetry. F Level of organization : They exhibiy the organ-system level of organization.
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CLASS NOTES FOR CBSE – 04. Animal Kingdom
F Germ layers : These are the triploblastic animals. F Segmentation : The body of annelids is metamerically segmented and the external segmentations the body correspond to the internal segmentations. F Locomotion : The annelids have the capability to locomote, whether they are terrestrial or aquatic. Some aquatic annelids also possess locomotory appendages. They bear fleshly, flattened, laterally projected structures (see Nereis) in their body, called parapodia (sing : parapodium). F Digestive system : Digestive system is complete and contains distinct mouth and anus at opposite ends of body. The digestion of food is entirely extracellular. F Circulatory system : Blood vascular system is usually closed. Respiratory pigments, either haemoglobin or erythrocruorin, are dissolved in blood plasma. Free amoeboid blood corpuscles are present, but there are no RBCs. In leech, there is open blood vascular system. F Excretory system : Coiled tubes are present in the body, called nephridia (singular : nephridium) which help in removing out the metabolic waste from body. These open out through the pores that excrete out the nitrogenous waste (urea and ammonia). Nephridia also halp in maintaining the body fluid (water) and salt concentration. Hence, nephridia help in excretion as well as osmoregulation. F Nervous system : Body control is provided by the nervous system consisting of paired ganglia (sing : ganglion) which are connected to the double ventral nerve cord by lateral nerves. These paired ganglia act like the brain of annelids. F Reproductive system : Earthworms and leeches are monoecious (hermaphrodites) as male and female sexes are not separate in them. Each individual of them produces sperms as well as ove. While Nereis is dioecious. In Nereis, male and female sexes are separate, sperms and ova are produced by different individuals. There is indirect development in Nereis. Larva when present is trochophore. Only sexual reproduction is seen in annelids (no asexual reproduction). Example
Nereis (Sandworm), Pheretima (Earthworm) and Hirudinaria (Blood sucking leech).
09. Phylum – Arthropoda : F It is the largest phylum in the animal kingdom including 900,000 species. The largest class is insecta with 750,000 species. General characters areF They are triploblastic coelomate and bilaterally symmetrical animals. F The body cavity is full of haemolymph (blood) and it’s known as haemocoel. The ture coelom is restricted to gonals. F The body is covered by chitinous cuticle, which forms the exoskeleton. Strengthen by deposition of minerals (Cal. Phosphate & Carbonate). F They have a segmented body, some segment bearing a pair of jointed appendages covered by a jointed exoskeleton. F Exoskeleton is made of chitinous cuticle that is shed at intervals. (Moulting/Ecdysis) F The process of casting off of sking or integument is known as ecdysis or moulting. Chitnnous exoskeleton is secreted by the underlying epidermis.
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F The body is divided into head, thorax and abdomen. In some cases the head and thorax is fused to form cephalothorax. In insects the thoracic segments have legs and wings, the abdomen has no legs in insects. F Muscles are striated. (1st time developed in Arthropoda). Respiratory organs are gills, book gills, book lungs or tracheal system. F Excretion takes place through green glands, malpighan tubules and coxal gland. (Nephridia in Peripatus). Excretory matter = Ammonia (Aquatic) ; Uric Acid (Terrestrial) F Sensory structures in arthropods are antennae for perceiving odour, eyes, statocysts or balance organs and sound receptors (in chirping crickets and cicadas). Eyes are compound. F The heart is dorsal pulsatile, many chambered and the circulatory system is open (Haemocoel). Blood haemolymph colourless.The central nervous system consists of a circumoesophageal nerve ring formed by paired pre-oral ganglia connected by commissures to a solid, dorsal ganglionated, ventral nerve chord. F In land arthropods, the fertilization is always internal. Few aquatic has external fertilization. F Arthropods are oviparous. In some like the scorpion, the eggs hatch within the female body. They bring forth the young ones alive. They are viviparous.
10. Phylum – Mollusca Introduction : Mollusca is the second largest phylum of animal kingdom. This phylum, includes the soft-bodies animals.
General characteristic features of Mollusca : (i)
Habitat : Mulluscs are found in all habitats : oceans, coral reefs, deserts, forests, rivers, lakes and even underground. Hence they are terrestrial as well as aquatic (marine or fresh water). (ii) Body symmetry : These are the bilaterally symmetrical animals. (iii) Level of organization : Molluscs have an organ-system level of organization. (iv) Germ layers : They are the triploblastic animals. (v) Segmentation : Segmentation is not found in body of molluscs hence they have an unsegmented body. (vi) Coelom : They possess a true body cavity or coelom lined by the mesoderm. So they are also the coelomates. (vii) Body form : Body is covered by a calcareous shell and is unsegmented with distinct head, visceral hump and muscular foot. Head is the anterior part of body which bears mouth and other structures like tentacles, eyes, etc. in some molluscs. (viii) Mantle (Pallium) : A soft and spongy layer of skin forms a thin and delicate covering over the visceral hump or pallial complex and is called mantle. Mantle is a characteristic feature of mollusc. It serves many functions like
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(a) It provides protection to the head anteriorly by acting as a protective hood over the head. (b) It secretes a calcareous shell over the body which protects it and acts like an exoskeleton absent in Octopus. This mantle cavity encloses the feather-like gills which help in the respiration as well as excretion. (ix) Digestive system : The digestive system is complete and bears separate openings for entry of food and exit of waste. The digestive glands are also present. The digestion is extracellular. The food of molluscs consists of microorganisms, vegetation (in snails) and dead plants and animal tissues. The mouth of molluscs contains a file-like rasping (feeding) organ called radula which is armed with the transverse rows of chitinous teeth. It is a curved, ribbon-like structure present in the mouth. (x) Respiratory system : In aquatic molluscs, gills are the respiratory organs present in mantle cavity while in terrestrial forms, lungs are the respiratory structures. The gills are called ctenidia (singular : ctenidium). They are the comb-like or feather-like gills. (xi) Circulatory system : Open circulatory system is present in molluscs in which blood pumped by the heart passes through large vessels into open spaces or body cavities called as sinuses. Respiratory pigment is haemocyanin. Amongst molluscs cephalopods have closed circulatory system. (xii) Excretory system : The gills also perform the excretion along with respiration, Gills separate fthe nitrogenous waste products from blood as they are richly supplied with blood. Excretion by paired Organ of Bojanus. Another excretory organ called Keber’s organ (Pericardial gland) is present. (xiii) Sensory system : The anterior head region may have sensory tentacles which are sensitive to touch. Along with tentacles, other sense organ like eyes (for light detection), statocysts (for balance) and receptors for smell, taste etc. are also present in their body which make these animals aware of their surroundings to get food, shelter and protection. Osphradium is a sensory structure which tests the chemical nature of water. (xiv) Nervous system : The nervous system consists of paired ganglia and several nerves to provide nervous supply to the body. (xv) Reproductive system : Molluscs are usually dioecious as sexes are separate in them e.g., Pila, Sepia, Loligo, Octopus, etc. Examples of monoecious forms are Aplysia, Doris, etc. Molluscs are usually oviparous (egg-laying). (xvi) Fertilization : Both external and internal fertilization are seen in molluscs. Usually internal fertilization in more common. (xvii)Development : Both direct and indirect development are seen in molluscs but usually indirect development occurs which is mediated by a free-swimming larval stage, like trochophore. Example
Neopilina, Chiton, Dentalium, Pila and Aplysia
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11. Phylum – Echinodermata : F Name Echinodermata was given by Jacob Klein. All are Marine except Synapta similis. Generally live at bottom and slow moving. F Body shape is star like, cylindrical like, melon-like, disc-like, flower like. F Body unsegmented with bilateral symmetry in larva and radial (arranged in five or multiple) in adult. Echinoderms are triploblastic with organ-system level of organization. F Echinoderms do not have head. F Tube feet (podia) which comes out through radial area i.e. Ambulacral used for locomotion. They are extended and retracted by variation in hydraulic pressure of fluid in them and by contraction of their muscle. F Body wall of echinoderms consists of (i) Epidermis – Single layered & ciliated. (ii) Dermis – Below the epidermis thick dermis having mesodermal endoskeleton of calcareous plate (Ossicles). It has spines. (iii) Muscles – Smooth and lie below dermis. Minute pincerlike structure pedicellariae comes out through skin. They keep body surface clear of debris by opening & closing. These are made up of three calcareous plates. F Echinoderms have true Coelom lined by ciliated mesothelium. Enterocoelous contain fluids with free amoeboid cells called coelomocytes. F Coelom is divided into many tubes and sinuses, which together form 3 systems (i) A unique water filled ambulacral or water vascular system with tube feet to help in food perforated plate madreporite permits entry of water into ambulacral system which also help in food and gas transport system. Structures like Pollian vesicle, tiedmann body or recemose, stone canal are also found in water vascular system. (ii) Haemal system. (iii) Perihaemal system F Respiration takes place by gills called dermal branchiae or papulae in most of Echinoderms like Starfish, genital bursae in Brittle star, cloacal respiratory trees Sea Cucumber, Peristomial gills – Sea urchin. tube-feets also helps in respiration in all Echinoderms. F Digestive tract is complete, mouth is ventral & anus dorsal (incomplete-brittle star). Circulation system is reduced and open type called haemal system / Perihaemal system. No heart or pumping vessel. F There is no specialized excretory organ system. Nitrogenous waste (ammonia) diffuses out via gills, bursae, respiratory tree and tube feet. Amoeboid cells in coelomic fluid also perform excretory function by absorbing excretory matter. F Nervous system is simple and primitive type includes a Nerve ring and radial nerve cord with simple sense organ. (No brain) F Echinoderms resemble chordates in early embryonic development. F Echinoderms have separate sexes.
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F Fertilization is external (no copulation). Life history includes ciliated, bilaterally symmetrical larva that undergoes metamorphosis and change into a radially symmetrical adult (Deuterostome). Larva of different forms of echinoderms : Star fish → Bipinnaria, Brittle star → Ophiopluteus, Sea urchin → Echinopluteus, Sea cucumber → Auricularia, Feather star → Doliolaria, F Few echinoderms (star fish) have great power of regeneration. They break off their arms for defence purpose. This phenomenon is known as Autotomy. F Echinoderms in angry or frightened state vomits out viscera (internal organ). This phenomenon is known as Evisceration. Examples : Asterias (star fish), Ophiothrix (the brittle star) Echinus (sea urchin), Clypeaster (cake urchin).
12. Phylum – Hemichordata / Stomochordata Introduction : Hemichordata was earlier considered as a sub-phylum under phylum chordata. But now it is placed as a separate phylum under non-chordata. Name Hemichordata (Greek, hemi-half, Chorde-Cord) literally means they are half chordates, a fact that is undisputed. This name was derived on the basis of a structure present in their body which was considered to be their ‘notochord’. But this fact is no more supported. General characteristic features of Hemichordata : (i) Habitat : It includes exclusively marine animals (like Echinodermata). (ii) Body symmetry : Hemichordates are bilaterally symmetrical animals. (iii) Level lof organization : They possess the organ-system level of organization. (iv) Germ layers : These are the triploblastic animals. (v) Coelom : These are the coelomate animals possessing mesoderm lined body cavity. (vi) Body form : These animals are very soft, fragile and worm-like appearance. The body is cylindrical in shape and is divisible into three distinct regions or parts. (a) An anterior proboscis : It is short and conical in shape. (b) Middle collar : It is a short and cylindrical part. (c) A long posterior trunk : It is flat and further differentiated into parts. (vii) Digestive system : Digestive tract is complete. (viii) Circulatory system : The circulatory system is of open type. (ix) Respiratory system : These are the aquatic animals and respiration takes place through the gills. (x) Excretory system : The excretion of nitrogenous waste takes place through proboscis gland. The gland collects the waste from blood and pass on it into the coelom of proboscis from where it is finally excreted through the proboscis pore, Proboscis pore is present at anterior region of proboscis.
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(xi) Reproductive system : Hemichordates are dioecious (sexes are separate). Reproduction is mainly sexual. Fertilization : Fertilization is external, i.e., in the sea water. Development : The development is mainly indirect with a free-swimming larve (Tornaria larve). Example
Balanoglossus (Tongue worm), Saccoglossus (Tongue worm),
13. Phylum – Chordata Phylum ehordata has four fundamental features. (i) Notochord (elastic, solid, ensheathed rod-like structure of vacuolated turgid cells which is present throughout the life or only during early embryonic development, located between nerve cord and digestive tube (alimentary canal). In vertebrates, notochord is replaced by a cartilaginous or bony vertebral column in adults. (ii) Dorsal hollow nerve cord : It differentiates into brain and spinal cord. It is present above the notochord. (iii) Paired pharyngeal gill slits : v Take part in circulation of water for respiration. v In higher chordates, they occur only in embryonic stage. (iv) Post anal tail : It is present for balancing. Along with these features chordates are bilaterally symmetrical, triploblastic, coelomate with organ system level of organization and close circulatory system. Table : Comparison of Chordates and Non-choedates Chordates (i) Notochord present. (ii) Central nervous system is dorsal, hollow and single. (iii) Pharynx perforated by gill slits. (iv) Heart is ventral. (v) A post-anal tail is present. (vi) Gut is ventral to nerve cord.
Non-chordates (i) Notochord absent. (ii) Central nervous system is ventral, solid and double. (iii) Gill slits are absent. (iv) Heart is dorsal (if present). (v) Post-anal tail is absent. (vi) Gut is dorsal to nerve cord.
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Classification of Protochordata or Acraniates Sub-Phylum – 1. Urochordata (i)
The adult body is enclosed within a leathery test or tunic formed of a cellulose-like organic substance termed tunicin, therefore, this phylum is called tunicata. (ii) Notochord is only present in the tail of the larva (hence named Urochordata) and disappears in the adult. (iii) Circulatory system is open in tunicates. (iv) Development is indirect. (v) Retrogressive metamorphosis shown by the larva i.e. change from better developed larva to less developed adult. (vi) Excretion by neural gland.
Example
Ascidia, Salpa, Doliolum, Herdmania (sea squirt), Pyrosoma (colonial bioluminiscent form)
Sub-phylum – 2. Cephalochordata (i) (ii)
Notochord extends from head to tail region. Notochord persists throughout the life.
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(iii) Digestive tract is complete. Pharynx large, perforated by numerous persistent gill-slits. (iv) NCirculatory system well-developed, closed and without heart. (v) NDevelopment indirect, including free swimming larva. (vi) NRespiration through general body surface. (vii) NExcretion by protonephridia with solenocytes. (viii) NPaired appendages absent. Median fins (dorsal, ventral and caudal) are present. Example
Branchiostoma (Amphioxus or Lancelet) Amphioxus has both ends pointed like lance, hence it its commonly called lancelet.
Sub-phylum – 3. Vertebrata/Craniata General characteristics of sub-phylum vertebrata : (i) Brain is enclosed within a cranium. (ii) Possess notochord during the embryonic period only. (iii) Notochord is replaced by a cartilaginous or bony vertebral column is the adult, thus all vertebrates are chordates but all chordates are not vertebrates. (iv) Vertebrates have ventral muscular heart with two, three or four chambers. (v) Kidneys are present for excretion and osmoregulation. (vi) For locomotion, they have paired appendages which may be fins or limbs. (vii) They are unisexual. (viii) They have single pair of gonads.
Division-1 : Agnatha (The Jawless Vertebrates) (i) (ii) (iii) (iv) (v)
They are the most primitive of all craniates. Mouth does not possess jaws hence named Agnatha. Notochord persists throughout life. They do not have exoskeleton and paired appendages. They have single nostril. (vi) They are cole-blooded.
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Class 1. Cyclostomata General characteristics of Cyclostomata (i) All living members of this class are ectoparasites on some fishes. (ii) They have an elongated body bearing usually 6-15 pairs of gill slits for respiration. (iii) Cyclostomes have a sucking circular mouth. (iv) Mouth is without jaws hence they are also called as jawless fishes. (v) Their body is devoid of scales and paired fins. (vi) Cranium and vertebral column are cartilaginous. (vii) Circulation is of closed type. (viii) Stomach is absent. (ix) Cyclostomes are marine but migrate for spawning to fresh water. After spawning, within a few days, they die. Their larvae, after metamorphosis, return to the ocean. Example
Petromyzon (Lamprey) and Myxine (Hagfish).
Division-2 : Gnathostomata (The Jawed Vertebrates) Gnathostomata : F F F F F F F F F
F F F F F F F F F
F
Mouth is surrounded by true jaws. Vertebral column well developed. Movement by paired fins or legs. Gonads are paired, genital ducts are present. 3 Semi circular canals are found in internal ear. Pineal eye is absent. Animals are unisexual. Gills or lungs are meant for respiration. Gnathostomata is classified into two super classes on the basis of locomotory organs, respiratory organs, heart and blood vascular system. Super Class : (i) Pisces (ii) Tetrapoda Body is covered by dermal scales. But Cat fish, Torpedo & Wallago are scaleless. Colour in fish produced by iridocytes present in the dermis. Paired fins are present for swimming. e.g. Pectoral and pelvic fins are paired. Unpaired fins are also found on the body e.g. mid dorsal fin and caudal fin. External nares are one pair. [Dirhynous condition]. External and middle ears are absent, only internal ear is present in which three semi – circular canals are present. Eyes are without lids. Respiration by gills, gills are 4 to 7 pairs. Naked or covered by operculum. “Air bladder” is present in bony fishes only which helps in swimming as well as in respiration. Heart two chambered, known as “Venous heart”, because it contains only impure blood, which from heart goes to gills for purification, pure blood is then distributed to all parts of body directly from gills, i.e. circulation of blood is unicircuit. RBC are nucleated. Sinus venosus, renal and hepatic portal systems are found in circulatory system.
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F F F F F
Endoskeleton is made up of cartilage or bones. Vertebrae in fishes are amphicoelous. (centrum is concave at both the surfaces) Only one occipital condyle is present, so that skull in monocondylic type. Cranial nerves are 10-pairs, Lateral line system is present in the body of fishes, which can detect vibrations (Rheoreceptor) and Electric field. F Kidney in fishes are mesonephric type.
Difference between Chondrichthyes and Osteichthyes Chondrichthyes (Cartilaginous fishes) Mostly marine Wholly cartilaginous
Osteichthyes (Bony fishes) Both marine and freshwater mostly bony
Placoid
Cycloid, ctenoid and ganoid
Caudal fin
Heterocercal (asymmetrical)
Mouth
Ventral on head
External nares Gill clefts Gills Air bladder (swim bladder)
Ventral Exposed 5-7 pairs
Homocercal (symmetrical) Usually terminal or subterminal on head Dorsal Covered by operculum 4 pairs
Absent
Present
Characters Habitat Endoskeleton Exoskeleton (scales)
Operculum Claspers N2 waste Cloaca Spiral valves Development
Absent (except) Chimaera) In males Urea Present Present in intestine Direct without metamorphosis
Present Absent Ammonia Absent Usually absent in intestine Indirect with metamorphosis
14. Superclass-2 : Tetrapoda (i) These possess two pairs of limbs. (ii) Skin is adapted to withstand exposure to air. (i) They have lungs for aerial respiration. (ii) Their sensory organs are adapted for reception in air, such as vision, hearing, smelling, etc. Tetrapoda is divided into four classed : Amphibia, Reptilia, Aves and Mammalia.
Class-1 Amphibia (Gr. Amphi : dual, bios-life) General characteristics of Amphibia : (i) They are poikilothermal animals. They are amphibious in nature, viz, they can live on land as well as in water. They are mostly found in warm countries. They are ectothermic (cold blooded).
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(i)
The skin is smooth or rough having cutaneous glands which keep it moist. They are usually without scales, but if present they are hidden beneath the skin (e.g. Caecilians). (ii) Two pairs of limbs are used for locomotion. (iii) ThesThe gills are present at least in the larval stage : Some adult forms also carry them in addition to lungs (e.g. Necturus). (iv) ThesThe respiratory organs are lungs, buccopharyngeal cavity, skin and gills. (v) ThesSkull is dicondylic, i.e. with two occipital condyles for articulation with vertebral column. (vi) ThesThe heart is three chambered, having two auricles and one ventricle. In the heart, there are present sinus venosus and truncus arteriosus. Both hepatic portal and renal portal systems are well developed. (vii) ThesKidneys are mesonephric. Urinary bladder is present in frog. Larvae and tailed amphibians (e.g. Salamanders) are ammonotelic. Frogs and toads are ureotelic. (viii) ThesEar consists of internal and middle ear. Tympanum (outer membrane) covers the middle ear. The middle ear has a single ear ossicle called Columella Auris. (ix) ThesTen pairs of cranial nerves are present. (x) ThesThey return to water for breeding. Male lacks copulatory organs. The metamorphosis is usually present. A fish like stage, the tadpole is present.
Class-2 : Reptilia (Latin – Repere or reptum, to creep or crawl) General characteristics of Reptilia : (i) The class name refers to their creeping or crawling mode of locomotion. (ii) These are the first true land vertebrates. (iii) Their body is covered by dry and cornified skin, epidermal scales or scutes. (iv) External ear openings may be present or absent. (v) Tympanum represents ear. (vi) Limbs, when present, are two pairs. (vii) Heart is usually three-chambered, but fore-chambered in crocodiles. (viii) Mouth is terminal with conical teeth which are pleurodont in lizards and snakes and the codont in crocodiles. Teeth are absent and replaced by horny beaks in turtles. (ix) Endoskeleton is bony, skull is monocondylic (with one occipital condyle). (x) Kidneys are metanephric. Excretion is uricotelic, Urinary bladder is absent in snakes and crocodiles. (xi) Cranial nerves are 12 pairs, Jacobson’s organ (vomeronasal organ) present in the roof of buccal cavity concerned with smell, is well developed in snakes and lizards. They do not have external ear openings. Tympanum represent ears. (xii) Reptiles are cold-blooded or poikilotherms. (xiii) Snakes and lizards shed their scales as skin cast. (xiv) Sexes are separate. (xv) Fertilization is internal. (xvi) They are oviparous, Eggs are covered by a shell. (xvii)Development is direct.
Class-3 AVES (Birds) General characteristics of aves : (i) Birds are feathered dipeds, truly flying vertebrate.
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(ii) (iii) (iv) (v)
Most of them can fly except flightless birds (e.g. Ostrich). They possess beak and have streamlined body. Forelimbs are modified into wings. The hindlimbs generally have scales and are modified for walking, swimming or clasping the tree branches. (vi) Skin is dry without glands except the oil gland or preen gland or uropygeal gland at the base of the tail for lubrication of features. (vii) Endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities. Such bones known as pneumatic bones and lack bone marrow. (viii) The digestive tract of birds has additional chambers, the crop and gizzard. (ix) Heart is completely four-chambered. (x) Only right aortic (systemic) arch persists in the adults. Renal portal system is vestigial. Erythrocytes are minute, oval and nucleated. The blood of the birds may be called the richest blood in the animal kingdom. It has more RBCs per cubic mm of blood than in any other animal. (xi) Kidneys metanephric ant three-lobed. Ureters open into cloaca. Urinary bladder is absent. Excretion is uricotelic. (xii) Cranial nerves are 12 pairs. (xiii) Olfactory organs are poor. Middle ear contains a single ossicle. Eyes possess nictitating membrane, Pecten is a comb-like structure found in the eyes near blindspot. Pecten helps in providing nutrition to the eyeball. Pecten is found in all birds except Kiwi. (xiv) They are warm-blooded (homeothermous animals) i.e. they are able to maintain a constant body temperature. (xv) Respiration is by lungs. (xvi) Air sacs connected to lungs supplement respiration. (xvii)Syrinx is present for producing voice, lies near the junction of trachea and bronchi. (xviii)Sexes are separate. (xix) Fertilization is internal. (xx) They are oviparous and development is direct.
Types of Feathers (i)
Quills : (a) They are large feathers found in wings and tail. (b) It has a central axis called shaft. (c) Small proximal part of the shaft is hollow, translucent and cylindrical and is termed as calamus. (d) The long-distal, solid and opaque part of the stem is known as rachis. (e) An umbilical groove extends all along the ventral side of rachis. (f) Small hole on the proximal end of calamus is known as inferior umbilicus, the hole on the distal end of calamus is known as superior umbilicus. (g) Each vane is composed of parallel filaments, the barbs. Each bears barbules. (h) The distal barbules of each barb bear small hooklets. (i) Emu bird have an after shaft as long as the main shaft.
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Class-4 : Mammalia (L. Mamma = breast) General characteristics of Mammalia : (i) The most unique mammalian characteristic is the presence of milk producing glands (mammary glands) by which the young ones are nourished. (ii) The They are found in variety of habitats – polar ice caps, deserts, mountains, forests, grasslands and dark caves. (iii) The They have two pairs of limbs, adapted for walking, running, climbing, burrowing, swimming or flying. (iv) The The skin of mammals is unique in possessing hair. (v) The External ears or pinnae are present. (vi) The Different types of teeth are present in the jaw. (vii) The Heart is four-chambered. (viii) The They are homeothermous. (ix) The Respiration is by lungs. (x) The Sexes are separate and fertilization is internal. (xi) The They are viviparous with few exceptions. For example, Ornithorhynchus (Platypus), which is oviparous. (xii) The Development is direct. (xiii) The In males, testes have come to lie outside the body cavity in scrotal sacs (except in elephants and aquatic mammals and prototherian mammals). (xiv) The Cerebral hemispheres and cerebellum are large-sized and highly developed with great increase in the cortex. The two cerebral hemispheres are joined by a transverse band of nerve fibres called corpus callosum. There are four solid optic lobes called corpora quadrigemina in the mid-brain. 12 pairs if cranial nerves. (xv) The middle ear has three ear ossicles called malleus, incus and stapes; the internal ear has a spirally coiled cochlea as an efficient organ of hearing. (xvi) The neck generally has seven cervical vertebrae.
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CBSE Pattern Exercise (1) (Q 1 to 3) One Mark 1. Why are corals important? 2. What is the difference between class Amphibian and class Reptilia in respect of their skin? 3. Which organ helps in excretion ii (i) Arthropods, (ii) Hemichordates? (Q 4 to 6) Two Marks 4. Distinguish between diploblastic & triploblastic animals. 5. Mention the unique features of phylum mollusca. 6. Distinguish between bony fish & cartilaginous fish. (Q 7 to 8) Three Marks 7. "All vertebrates are chordates but all chordates are not vertebrates" justify the statement. 8. Enlist the main characteristics & examples of plylum porifera. (Q 9 to 10) Five Marks 9. How are non chordates different from chordates. Write the major phyla of non-chordate & give examples. 10. Enlist the main features of Aschelminthes & give examples.
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ANSWER Q1 Have skeleton composed of calcium carbonate which gets deposited and can lead to formation of land forms. E.&. Lakshadweep (a coral island). Q2 Ambhibia (i)
skin is mois and slimy
(ii) lay eggs inside the water (iii) Their larvae have gills.
Reptilia (i) skin is sry and covered by scales of scute plates (ii) lay eggs outside the water. (iii) no larva is produced
Q3 (i) (ii)
Malpighina tubules, proboseis gland.
Q4 Diploblastic animals Diploblastic animals have two germ layers outer ectoderm & inner endoderm in their embryo gastrula stage
Triploblastic animals Triploblastic animals have three germ layer outer ectoderm middle mesoderm & inner endoderm in their embryo gastrula Eg. all animals except porefera & coelentrata
Eg. Hydra, Obelia, Porpcta Q5 (i) (ii) (iii) (iv)
Body soft as well as unsegmented The body is covered by calcareous shell & mantle. Body is divided into-head, visceral mass &foot. Buccal mass possesses radula.
Examples of Mollusca: (a) Pila (b) Octopus
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Q6 Bony fishes (i) They are called osteichthyes (ii)
Their endoskeleton is bony.
(iii) They are found in sea & fresh water both. (iv) They have swim bladder. (v) Gills are covered by opercula. (vi) Eg. Salmon, catla Rohu.
Cartilaginous fishes (i) They are called chondrichthyes. (ii) Their endoskeleton is cartilaginous. (iii) All are marine forms. (iv) They have five pairs of gills (v) operaculum absent (vi) Rays, scoliodon, electric ray.
Q7 All vertebrates are chordates because they possess three basic chordate features as:(i) All chordates posses a notochord (ii) All chordates have a dorsal hollow nerve cord. (iii) All chordates have pharyngeal gill cleft in some stages of lift cycle All chordates are not vertebrates. Vertebrates have vertebral column but protochordates & agnatha have notochord that is not replaced by vertebral column. Q8 (i) (ii) (iii) (iv) (v)
They are commonly called as sponges They are generally marine. diploblastic, bilerally symmetrical They have water transport mechanism They are very primitive multi-cellular animals with cellular level of organization. Water can enter by pores Ostia in body wall directly or throught canal into spongocoel. From it goes out by means of osculum. It is called canal system (vi) The digestion is intracellular (vii) Body is supported by a skeleton which consists of spicules (viii) Sexes are not separate (ix) They reproduce asexually by fragmentation or sexually by formation of gametes (x) Fertilization is internal example-euplectella, Sycon, Spongilla, Euspongia Q9 Non-Chordates (i) Notochord is present (ii) Central Nervous system dorsal, hollow & single. (iii) Pharynx is perforated by slits (iv) Heart Ventral (v) A post anal metamerically segmented tail present Q10 (i)
Chordates (i) Notochord is absent (ii) Central nervous system is ventral solid & double (iii) Gill slits absent (iv) Heart dorsal (v) Terminal part uunsegmented
They are called Round worm as they appear circular in C.S.
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(ii) Free living, aquatic, terrestrial or parasitic (iii) Organization of body is organ level (iv) Bilaterally symmetrical animals (v) They are triploblastic & pseudocoelomate (vi) Alimentatin complete with muscular or pharynx (vii) Sexes are Separate (viii) Body is covered by cuticle (ix) Fertilization is internal (x) Examples are filarial worm (wuchereia), Ascaris, Pinworm (Enterobuis) Hookworm (Ancyclostoma)
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