Sunday, 24 June 2012


FOOD VACUOLE-The numerous non-contractile food vacuole or gastrioles can be seen moving with the streaming endoplasm.They differ in shape and size accourding to the nature of the ingested food particles but mostly they are rounded in form.
ORAL APPARATUS-In paramecium the oral groove leads ventrally and posteriorly as a tubular structures called the vestibule. It leads directly into a narrow passage the buccal cavity. In its turn it opens into a narrow gullet or cytopharynx through a narrow aperture the cytostome.The  cytopharynx at its proximal end formsa food vacuole.The buccal cavity at the right is bordered by a row of cilia forming the endoral membrane.These are the ventral peniculus ,dorsal peniculus and quadrulus.These ciliary rows constitute the membranelles.Rows of normal somatic cilia linethe wall of vestibule.

Thursday, 21 June 2012


ABSORPTION-The digested food gets diffused into the endoplasm, where it is assimilated into the protoplasm.The exess food may be stored as glycogen,paramylon ,lipids chromatoid bodies.
EGESTION-The indigestible residue of the food  is expelled from the hinder part of the body in the case of moving amoeba at any point.ciliated often possesses a special opening the cytopyge or ectoproct .


TRUNK-It comprises the entire body only the head and the last body  segment the pygidium.It consists of 80-200 similar segments the pygidium.each broader than long and characterized by the presence of a parapodium on each lateral side.
PARAPODIA-The parapodia are antero-posteriorly flattened vertical flap like outgrowth of the body wall on the lateral sides of the trunk segments.The parapopodia are hollow structures enclosing coelom which is continuous with that of the trunk segments.The parapodium is typically biramous it consists of a proximal basal region bearing distally two parts a dorsal notopodium and a ventral neuropodium The parapodium part is further subdivided into two leaf like lobes or lingulae a dorsal superior lingula and a ventral inferior lingula.The each part of parapodia bears a base slender ,tentacular process known as cirrus ,the dorsal cirrus borne dorsally by the notopodium is slightly larger than the ventral cirrus.The each part of parapodia is supported internally by a deeply -embedded long stout and black chitinous rod known as aciculum.The aciculum also serves for the attachment of setal muscles thus serving as a sort of endoskeleton.Each part bears a bundle of long fine stiff chitinous bristles the setae or chaetae which project beyond the setae or chaetae which project beyond its margin. Each seta is lodged in a setal or setigerous sac,formed by the inpushing of the epidermis and base of the sac.The setae can be protruded ,retracted or turned in various directions with the heip of the setal muscles. Each seta is a two-jointed structures with a proximal shaft and a distal blade.The long bladed has a small shaft and a long slender straight and pointed blade with one edge serrated.The typical has a large stout shaft and a short ,stout blade with an incurved notched tip.The oar-shaped of seta occurs in the sexual phase or the heteroneresis in which the blade becomes oar-like.The sharp setae are used for protection and for obtaining a hold on the smooth inner walls of the burrows.

Wednesday, 20 June 2012


BODY DIVISION-The body of nereis is metamerically divided into a number of metameres or segments arranged in a linear series.The number of segments is fairly constant for a species about 80 in N.cultrifera and N.dumerilli and about 200 in N.virens.The distinct regions can be identified in the body .
HEAD-Nereis possess well developed head corresponding to its active life and predaceous habit.It lies at the anterior and consists of two parts.
PERISTOMIUM-It is large,segment like part of the head surroundings the anteroventrally situated and transversely elongated,slit like mouth.It is formed by the fusion of first two embryonic segments during cephalization.It differ from a trunk segments in being longer, in lacking parapodia and in the presence of two  pairs of thread like peristomial cirri on each side.These are homologous with the notopodial cirri and neuropodial cirri of the parapodia of trunk segments.The dorsal cirri are longer than the ventral ones.
PROSTOMIUM-It is a roughly triangular ,dorso-ventrally flattened fleshy lobe lying above and in front of the mouth.It bears two pairs of simple pigmented eyes on the dorsal surface a pair of short cylindrical sensory prostomial tentacles.The palps are contractile and their small distal joints can be retracted into their large proximal joints.

Monday, 18 June 2012


LARVAE OF CRUSTACEA-Crustacea developed both direct and indirect development.The adult is attained by a progressive growth and differentiation where as in the latter there is a larval stage which differs from the adult in many features and acquires adulthood through metamorphosis.
NAUPLIUS-It is simplest and commonest type of larva found in most marine crustaceans and a few malacostracans.The nauplius is the earliest and the basic larva.The body is minute with three indistinct of appendages -the uniramous antennules, biramous antenne and mandibles.In other crustaceans it may give rise to other intermediate larval forms such as metanauplius,protozoaea,zoaea,mysis.

Sunday, 17 June 2012


SEPTA-The body cavity of earthworm is a true coelom which lies between the body wall and the alimentary canal.It is lined by the coelomic epithelium derived from the mesoderm.The coelom is partitioned into a series of coelomic chambers by transverse intersegmental septa. The septa are absent in the first four segments.The first septum lying between segment 4and 5 is thin and membranous.The next five septa are thick and muscular.Septum between 8/9 or9/10 is lacking. The first nine septa up to septum 13/14 are without perforations.The remaining septa begining from septum 14/15 are perforated by numerous sphinctered apertures,through which adjacent coelomic chambers maintain continuity.


The coelom filled with an alkaline ,colourless or milky coelomic fluid containing water,salts some proteins and at least four type of coelomic corpuscles areas follow
1>PHAGOCYTES-The largest and more numerous nucleated amoeboid corpuscles or phagocytes ingested granules such as bacteria.
2>MUCOCYTES-These are elongated cells each having a broad fan-like process attached to narrow nucleated body.
3>CIRCULAR NUCLEATED CELLS-The coelomic corpuscles are rounded nucleated and blood corpuscles like cells having protoplasm .
4>CHLORAGOGEN CELLS-These are called yellow cells or star shaped small sized cells. They become deep yellow when stained with iodine solution.

Saturday, 16 June 2012


SETAE-The middle of each segment there is a ring curved bristles called setae or chaetae,formed of a horny nitrogenous organic substances,known as chitin. Each seta is embeded in a small pit in the bodywall, called the setal sac. It is yellow in colour and is shaped like an elongated 's' with a swollen middle part ,called nodulus.The arrangement of numerous setae in a ring in each segment is known as perichaetina arrangement as, in pheretima.
GENITAL PAPILLAE-The genital papillae one pair in the 17 and 19 pair segment on the ventral surface.The each papilla bears a shallow cup-like depressions at its top which acts a sucker during copulation.
SEGMENTATION-The soft and naked body of earth worm is divided into 100 to 120 segments called metameres or somites.The external segmentation corresponds with the internal segmentation of the body.

Friday, 15 June 2012


PERISTOMIUM-The first segment at the anterior end of the body is called the buccal segment or peristomium having crescentic mouth.It is prolonged into a fleshy lobe the prostomium.
CLITELLUM-The clitellum is completely surrounds the 14 to 16. Due to its presence the body is distinguised into per-clitellar ,clitellar and post-clitellar regions.The clitellum is a glandular organ which secreates mucus,albumen and an egg or cocoon for the eggs.It is girdle-like thick bad of glandular tissue.

Thursday, 14 June 2012


The body wall ' which encloses the spongocoel , is relatively simple.It consists of two cellular layers,the pinacoderm and choanoderm with a non-cellular mesenchyme in between.
PINACODERM- It consist of thin and flat polygonal cells, the pinacocytes .It help in the protection to the body.The pinacocytes are hexagonal in surface with thin margin and a bulging central part  containing a nucleus. The margin contractility so that the sponge can increage or decrease slightly in size.In the body wall are special large and tubular cells called the porocytes. They are supused to be a modified  tubular pinacocytes. Each porocyte contains a central like space,communicating with the outside as well as the spongoel. These spaces are called the ostia or dermal pores or incurrent pores. These help water to flow from outside into the spongoel.
CHOANODERM- The choanoderm cells are also called gastrodermis.It consist of a single layer of flagellated cells the choanocytes.The choanocyte consist of an ovoid cell with free end bearing a transparent contractile collar.The collar surrounds a single long flagellum which arises long flagellum from basal granule.The nucleus lies at the centre of its cell body.The choanocytes use for feeding and for ensuring the flow of water with the animal body.
MESENCHYMES-In between the pinacoderm and choanoderm there is secreated matrix of gelatinous protein that contain several types of freely wandering amoeba like cells or amoebocytes and the skeletal elements of calcium carbonate called as spicules or sclerites
a>AMOEBOCYTES-The larged sized amoebocytes with blunt pseudopodium and large nucleus are the archaeocytes.These contain much RNA .The archaeocytes are self-replacting and also capable of giving rise to all other types of amoebocytes.They give rise to additional pinnacocytes and choanocytesto the collencytes to the scleroblastsor sclerocytes and to the reproductive cells. The archaeocytes carry on all the functions essential for the life of the sponge.
b>SPICULES-These skeletal elements are small or large formed of crystalline calcium carbonate.The needle like spicules are monaxons.Whilesome tetraxons secondarily become triradiate due to loss of one ray.The spicules remain embedded within the mesenchyme.All spicules orient in the same direction.

Wednesday, 13 June 2012


   NERVOUS SYSTEM-The nervous system is developed and resembles the turbellarian .The brain form the a collar or ring(cerebral ring) around the pharynx and bears a pair of lateral cerebral ganglia and a ventral ganglion.Three pairs of longitudinal nerve cords extend posteriorly,giving out numerous fine peripheral branches, to the various organs,of  the three pairs of nerve one pair is dorsal, one ventral and one lateral.Between the dorsal and ventral cords, the lateral cords are well developed and connected by a few transverse commissures.              


ORAL GROOVE-The ventral surface of the body bears a prominent,shallow depresion called as oral grrove.It extends from the middle of the body and extends to the left side of the anterior end.
PELLICLE-The external envelops of the body is a living ,clear,firm and elastic cuticular membrane,called as pellicle.The pellicle to be series of polygonal depressions with their raised rims.The pellicle of paramecium includes a three membrane 1>outer cell membrane
2>outer alveolar membrane
3>inner alveolar membrane.
There is pit in the centre of the each alveole or alveolus which forms a polygon It is a pit in the center of each alveole or alveolus which form polygon. All the alveoli collectively form a continuous alveolar which is delimited by an outer alveolar and inner alveolar membranes..

Tuesday, 12 June 2012


TRICHOCYSTS-The trichocysts first seen in paramecium in by  Elis.It is rod like structure or oval organelles present through out the ectoplasm alternating with basal bodies and oriented at the right angles to the body surface.These small in size .It consist of elongated shaft and a terminal pointed tip called the spike or barb covered by a cap.The matrix of the shaft consist of a dense mass  of a fibrous protein called as 'trichinin'.The main function of trichocysts is to anchor the animal to a firm substratum when it feeds upon bacteria.It occur in a span of a few milli seconds.when fully discharged the shaft becomes a long cross-straites rod and measures about 40 mew in length.
NUCLEUS-Thereis two type of nucleus present in paramecium.It is heterokaryotic in nature.In p.caudatum there is a large macronucleus and a small micronucleus.The macronucleus is roughly kidney-shaped with inconspicuous nuclear membrane.It is polyploid and posses many nucleoli and much chromatin material.
MACRONUCLEUS-It is somatic or vegetative nucleus and controls the day to day metabolic activites of the cell.It is derived from micronucleus during reproductive processes.
MICRONUCLEUS-It is a depression like structure on the surface of the macronucleus.It is usually spherical and with a nuclear membrane and diploid number of chromosomes.It control the reproductive activities of the organisms.


The hydra live attached by their pedal discs to objects in water.Depending on the colour the brown and white hydra can fixed at one spot for some time but green hydra move about tfrom one place to another by several ingenious devices.All the movements are caused by the contraction or the expansion of the contractile muscles fibres. The gastro dermal muscles fibres are less developed in most part of the body wall,the movements are largely due to the contraction of the epidermal muscles fibres.
1>EXPANSION AND CONTRACTION-It is the process by which hydra ,when hungry ,remain attached to a substratum in water and frequently expands and contracts itself at intervals.This process is called contraction burst.This behaviour of hydra is guide by pacemaker located inhypostome. The contraction of one side and elongation of other side of the body or tentacles result in the bending and swaying movements which assist in the capture of prey.
2>LOOPING-The hydra also move from one place to another in search of food.With the help of glutinant nematocysts the tentacles attach to the substratum. The pedal disc is released and brought up closer to the circlet of tentacles and attached .The whole process which is repeated again again appear like a series of looping movements of a caterpillar or leech.
3>SOMERSAULTING-It is process of progression the animal somersaults like an acrobat.It is a slight modification of the looping locomotion.It result in hydra to assume an inverted posture.Hydra perform a series of somersaults by repeating the process.
4>GLIDING-IT can slide or glide slowly over the substratum due to creeping amoeboid movements of the cells of the pedal disc.
5>WALKING-The type of movements take place on some objects such as leaf and in leisurely hours.It can be slide or glide slowly over the substratum due to the creeping amoeboid movements of the cells of the pedal disc.
6>CLIMBING-Some hydra e.g pelmatohydra oligactis can evn climb by attaching its ling tentacles to some objects releasing the foot,and then contracting the tentacles ,so the body is lifted up.
7>FLOATING-The hydra throws its body free and floats on the water surface with the waves in water.
8>SURFACING-Hydra uses a gas bubbles secreated in mucus by the cells of the pedal disc,to rise in water and float at the surface.
9>SWIMMING-The some hydra free it self from the substratum and swims in water by the undulating wave-like movements of the tentacles and the body.

Monday, 11 June 2012


TRICHOMONIASIS-Trichomonas, is the main species which which cause this.Its body is rounded with one nucleus,an axostyle,a parabasal body 4-6 flagella and one back-wardly directed flagellum. e.g trichomonas vaginalis that inhibits the vagina of women and causes vaginitis.The disease is characterized by inflammation,burning sensation,itch and frothy vaginal discharge. The transmission is always cause by the male who act as intermediaries.
BALANTIDIAL DYSENTERY-The disease is caused by BALANTIDIUM COLI, intestinal ciliate. It is characterized by diarrhoea and ulceration of the large intestine.Through food and water the transmission of the parasite take place.

Sunday, 10 June 2012


During the time of ingestion a minute aperture called cell anus called as cytopyge or cytoproct is visible. Behind the posterior end, a little  small portion of the ectoplasm and pellicle is present.
FOOD VACUOLES-The numerous non-contractile called as gastrioles by vokovsky is present .The food vacuoles moving with streaming endoplasm.They are round in shape they differ in shape and size accourding to the nature of the ingested food particles.
ORAL GROOVE-The ventral surface of the body bears a prominent oblique and shallow depression called as oral groove. It originates from the middle of the body and extends to the left side of the anterior end.

Friday, 8 June 2012


It is caused by entamoeba histolytica also known as amoebic dysentery. Its trophozites that penetrate the wall of the intestine,secrete histolttic enzymes and feed upon its cells causing the formation of ulcers. These ulcers rupture and discharge blood and mucus into the intestine that pass with stool. The trophozoites under certain circumsrances reach the liver and brain also cause abscess formation.No intermediate host is involved in the life cycle of the parasite. Through the tetranucleate cysts  the transmission of the parasite from man to man. further the trophozoite changes into a smaller minuta form which other side form the tetranucleate cyst. The cyst are voided with the faecal matter and contaminate food and water spread into new host. e.g house flies.
Amoebic dysentery is endemic in warm countries .Medicines used for these are Emertin, fumagillin,erythromycin,aureomycin,metromidazole.


It is caused by the species of leishmania, the leishmania donovani is the causative agent of kala-azar or visceral leishmaniasis.Mostly  widespread inindia,south china and in mediterranean countries. The major cause is the enlaregement of spleen due to blockage of reticulo-endothelial system by parasite.l.tropica is the causative agent of skin leishmaniais.l.brasilliensis causes a disease called espundia.The development of uiceration in nasal cavities,mouth and pharynx is quite frequent.Leishmania species are transmitted from man to man by bites of sandflies belonging to the genus phlebotomus.


The mosquito belong to the group diptera. There are two familes of mosquitoes culicinae and anophelidae.when sitting the abdomen of anopheles is always held at an angle to the surface while that of culex is held parallel to the surface.
COPULATION AND OVIPOSITION-The two sexes copulate during flight.The male get attached to the female with the high pitched whine.Before takes a meal the female lay egg .They lay egg of about 200 to400 egg in cluster in ponds,ditches,marshes,street gutters or water barrels.with the hind leg they are cemented togher to form a small floating RAFT.
EGGS-The egg are white,elongated and cigar-shaped.The air bubbles,entangled among the upper narrower ends,assist in floating .The egg become dark grey.
IMAGO-The pupal stage last for 3 or 4 days. The completion of metamorphosis is result into adult insect called imago.The pupal skin now spilits along the back between the two respiratory trumpets.The imago emerges out with well-developed wings and after a few moments flies away.The complete life cycle takes place for ten to several days.The female lives for one month or more and the male for about a week.

Thursday, 7 June 2012


TROPIDONOTUS-This is common snake found in pond,or also called grass snake.It feeds on frogs,toads,fish. Body is stout,cylindrical and 1 meter long.Body is rough due to keeled scales. Colour is yellow or brown with black spots. e.g T.quincunciatus,two black streaks run behind from each eye. It is not harmless.
LYCODON-The maxillary fangs are not grooved but adapted for catching these slippery lizards.Colour is brown above with white cross bars all over the body.e.g wolf snake grows to 60 cm.The ridge runs along the sides of abdomen and tail.Incolouration it mimics the poisonous krait, but is non-poisonous.
DRYOPHIS-The whip snake has excessively slender body like the cord .Head is narrow,long with a tapering snout.Pupil is horizintal.posterior fang like maxillary,teeth is grooved.Having green colour.It is viviparour and feed on small birds and reptiles.The non-poisonous snake its saliva is weakly poisonous so they was able to kill small animals.

Tuesday, 5 June 2012


The poisonus snake include <1>poison gland <2>ducts <3>fangs <4>muscles.
<1>POISON GLAND-The sac like poison gland is situated  on either side of upper jaw, below the eyes .The are modified superior labial or parotid glands. The gland be small and oval ,large or tubular .The gland is sticky ,encapsulated with fibrous connective and mostly covered by a fan-shaped constrictor muscle,as temporal or masseter.Its stretching during biting squeezes poison from gland into its duct.
<2>POISON DUCTS-The poison duct leads anteriorly from poison gland to the base of a poison fang to enter its groove .
<3>FANGS-The fangs are certain specialized teeth attached to maxillary bones.Fangs are long,curved ,sharp and pointed.They use hypodermic needles for injecting poison into the body of victim.The fangs occur in poisonous snakes.
<a>SOLENOGLYPHOUS-The large functional fang occurs on the front of each maxilla.The base is covered with reserve and developing fangs.The fangs are movable and turned to lie to the roof of mouth .The hollow poison canal lined with enamel runs through the fangs opening at the tip.e.g vipers,rattle.
<2>PROTEROGLYPHOUS- The front of maxillae are permentely erect, the fangs are small. Each fang is grooved all along its anterior face.e.g cobras,kraits, coral snakes and sea-snakes.
<3>OPISTHOGLYPHOUS-The fangs are small,lie at the back of maxillae .e.g family colubridae.

Monday, 4 June 2012


It is called rough-tailed snake.It is similiar to blind snake having a short tail ends flat rough shield.Teeth are found in both jaws.It is viviparous. e.g uropeltis grandis.
TYPHLOPS-Having a size of 175-180 cm long.It looks like earthworm,hence the worm snake.Tail is blunt. Body scales are small,uniform and semicircular. Blunt scales is covered with large shield. Eyes are vestigial and hidden beneath shing scales,called as blind snakes. Teeth are abesent in lower jaw. It is harmless and feeds on insect larvae and termites.e.g T.braminus and T.thurstoni.

Sunday, 3 June 2012


Giraffe,giraffa camelopardalis,tree-studded grasslands of E.Africa.It is the tallest the living animals reaching a height of 6 m above ground.Head in both sexes carries 3 to 5 small bony horns covered by velvety skin. It is prehensile tongue can extend up to 50 cm to eat leaves of trees. Giraffe is fast enough to outrun most of its enemies. It cannot make sound.


Family hemirhamphidae,order beloniformes. found in rivers and ponds of w.bengal and orissa,called haif-beaked fish.lower jaw projected beyond the upper jaw,both having pointed teeth.
DIODON-family diodontidae,order tetraodontiformes. similar to tetradon in structures and habit aiso called as porcupine fish. occurs from red sea through out indian seas to pacific ocean.

Saturday, 2 June 2012


Cat fish clarius batrachus  has accessory respiratory organs.These are in the formof two much branched tree-like dendritic or arborescent organs developed inside suprabranchial cavities one on either side above the gill chambers. The cavities and the organs are covered by vascular mucous epithelium and functions as lungs. The fish periodically reaches watter surface to renew air.
HETEROPNEUSTES-This catfish has a pair of long tubular and dorsally situated air sacs arising posteroorly from gill chambers and extending almost up to the tail.They are highly vascular .The air is drawn in and expelled out through pharynx.


The poisonous snakes are cobras, kraits,pit less vipers  pit vipers,sea snakes and coral snakes. Their tails are cylindrical teeth modified into fangs.Their tails are cylindrical except in sea snakes.Head are covered into shields and ventral shields cover the entire width of belly .