Tuesday, 20 November 2012


1>They having sexual dimorphism.
2>Male bird having a glistening metallic black all over the body.
3>The bird having meladious voice.
4>Koel having nest parasite.
5>The male is better known by its meladious voice.


1>It looks like sparrow and lives in flocks.
2>It is among the world,s best nest builders.

3>Weaver birds damage cereal crops.

Thursday, 15 November 2012


HAND-1>The carpus contain nine small carpal bones.
2>These are radiale,intermedium and ulnare in proximal rows.
3>The centrale, trapezium,trapezoid,magnum,unciform in distal row.
4>The terminal phalanx bears a horny claw.
5>There are five elongated metacarpals,and phalanges are respectively.

Monday, 12 November 2012

Zapus hudsonius preblei(preble meadow jumping mouse)

1>Commonly called as jumping mouse.
4>The mice are born without hair and lively nearly 2 years.
5>They are eat plants,insects spiders or slugs.

Saturday, 10 November 2012

Rangifer Tarandus tarandus(reindeer)

1>Know as caribow in North-America.


1>The elephant the largest living mammals found on land.
2>It lives in dense tropical and subtropical forests near water.
3>Indian elephant is different from african elephant.


1>Family is phasianidae.
2>commonly called as mor or mayur.
3>In india occur about 1650 meters in himalayas.
4>Having sexual dimorphism.
5>Male having gorgeous ocellated tail.
6>It national bird of India.


1>Belong to family Otididae.
2>Having largest flying bird in the world.
3>It is commonly called as hukna,tuqdar,or gorawan.
4>Bird having 1 meter tail.
5>Its plumage is dull brown above and white below.
6>It is no longer an endangered bird in Rajasthan.


1>It is commonly called as wallich pheasant.
2>It is a vulnerable species.
3>It is only monotypic genus.
4>family is phasianidae.
5>phylum is chordata
6>kingdom is Animalia.
7>order is galliformes.
8>Red list category isvulnerable.


1>It is commonly called as sea-pentagon.
2>The central disc is large and the five arms are short and tapering.
3>The aboral surface bears immovable tubercles,a madreporite and anus.
4>The oral surface is concave,having a central mouth.
5>The upper marginal plates are smaller than the ventral ones .


SPIUNCULUS-1>It is commonly known as PEA-NUT.
2>About 25 cm cm in length
3>The circulatory system is absent.
4>The coelom is large and undivided.
5>The fertilization is external.
6>The larva is trochophore larva.
7>The spiunculus is generally sedentary and feeds upon detritus.

Thursday, 11 October 2012


1>The cypraea are commonly called as ,cowrie,.
2>It is marine gastropod found in Indian and Pacific oceans.
3>It is univalve.
4>The body having single ospharidium and kidney because of single torsion.
e,g Cowrie shells  used in indoor games,called chowpad.

Monday, 8 October 2012


1>In the13 th segment their are pair of white digitate ovaries.
2>Each ovaries is a white compact mass .
3>The ovaries present in the posterior of the septum.
3>The ovaries present in the ovarion lobes of the septum.

Sunday, 7 October 2012


It, is commonly called as, 'feather star'. It occurs in sea waters of the Atlantic, Western Africa , the mediterranean and west of Tropical America .It is an unstalked but attached crinoid, possessing a central cup-shaped disc which is covered by leathery skin. The oral surface is directed upwards.The branch dichotomously to form 10 arms and each of them bears a row of small and slender branches , called pinnules.The mouth radiate five ambulacral grooves which divide to form 10 grooves . The sides of each ambulacral groove are rows of finger like podia without suckers.The aboral surface bears numerous long, cylindrical appendages the cirri meant for gripping the substratum.

Monday, 10 September 2012


Cestodiasis is caused by tapeworm.
TAENIASIS-This disease is caused by the species belonging to the genus Taenia, which include T.SOLIUM and T.SAGINATA. In the intestine the cysticerci develop into adult tapeworm.The presence of tapeworm in intestine causes gastro-intestinal disorder. Some patients complain of hunger pain. Preventation is eating of throughly cooked pork,or beef.
HYDATID-The disease is caused by the hydatid worm,ECHINOCOCCUS GRANULOSUS .The primary hosts is dog in which they used eggs which are set free. These are pass out in faeces and develop into onchospheres .In man the hydatid cysts develop in the liver, lungs and tissues and represent the end of the parasitic life-line. The cysts causes inflammation of the tissues. The presence of cysts in the brain and kidney may prove fatal.

Friday, 7 September 2012


The  dorsal lip bears two minute double papillae  where as single papillae are called amphid. The amphidas are probably chemoreceptors , while the other sensory papillae are perhaps tangoreceptors. The posterior end of the male bears ventral 50 pairs of per-anal papillae in front of the cloacal aperture and 5 pairs  of postanal  anal papillae . The first two pairs of post-anal papillae are double. These papillae of the male help in copulation.

Tuesday, 4 September 2012


The diarrhoea is a flagellate parasite,intestinalis. It is present in small intestine. The cell body is pear-shaped with dorsal side convex and ventral side flattened and deepened anteriorly to form a suction groove. The nuclei and four pairs of flagella arranged symmetrically. The parasite divide by binary fission to multiply rapidly and feeds upon aminoacids and vitamins .It causes intestinal disorders leading to epigastric pain, abdominal discomfort,loss of appetite and headache. The transmission of parasite takes place through cysts which are voided with the faces and enters the new hosts . The infection of Girdia is more in children  than in adults .

Saturday, 1 September 2012


The nyctotherus is the intestinal,endo-commensal of amphibians and some invertebrates. The n.ovalis present in the intestine of cockroaches and N.cordiformis i the rectum of frogs. The outer surfaces are oval measuring about 60-120 mew in length. The outer surface bears longtitudinal and slightly spiral rows of cilia.The cytoplasm includes of a contractile vacuoles a macronucleus and food vacuoles.The cytopyge a permanent pore for the egestion of food is located at its hinder end. The nutrition is holozoic and reproduction takes place by binary fission and conjugation.

Thursday, 30 August 2012


1.KAPPA PARTICLES-In conjugation the particles that survive is called killers and other are called sensitive. The one which survive are called killers and other self-replacting the cytoplasmic bodies are called kappa particles.These are associated with the production of a killing substances ,paramecin. The kappa particles diffuses out into the surrounding water and causes the death  of kappa particles it was found that a dominant gene in nucleus is necessary for kappa to exist,multiply and produce paramecium.
2.Pi particles-These are mutant forms of kappa particles. They do not release any toxic substances meant for killing those which are without such particles.
3.Mu PARTICLES-These particles are also killers and kill the mate without such particles, during conjugation.
4.LAMBDA PARTICLES-These are borne by killer paramecia and causes the sensitive paramecia to lyse or disintegrate.

Tuesday, 28 August 2012


The medusa is carnivorous.The food includes minute worms.These are capture by nematocysts-bearing tentacles and ingested by the highly contractile mouth.The prey is digested exclusively in the stomach.The digestion is both extracelluiar and intracellular like that of the hydranth. The digested food is diatributed to the entire medusa through the system of the radial and circular canals.


The elimination of soluble metabolic wastes from the protozoan body usually occurs by diffusion. The excreation by diffusion through the whole surface of the body takes place in marine and endoparasitic protozoans. In fresh water forms where the contractile vacuoles perform the function of osmoregulation some soluable wastes are also expelled with the outgoing water.

Sunday, 26 August 2012


The cytoplasm is commonly divided into two areas-the peripheral ectoplasm and the central endoplasm. The endoplasm contains the organelles found in metazoan cells,including mitochondria,golgi bodies,. The structures like trichocysts contractile vacuoles ,stigmas,which are exclusive of protozoa are seen in certain individuals.

Friday, 24 August 2012


Fungia are commonly called as 'Mushroom coral'. It is large and solitary coral. The skeleton or the corallite is discoid and convex on the upper and concave on the lower side.The numerous septa are small calcareous rods,the synapticulae. The ypung polyp,called anthocyathus, is attached by an anthocaulus,but the adult is free, large and lies at the bottom. It bears short tentacles and is without siphonoglyph.

Tuesday, 21 August 2012


The skin serves as protective covering ,the skin act as respiratory function.The capillaries containing the haemocoelomic fluid extends in between the cells of the epidermis .The carbon -di-oxide of the haemocoelomic fluid passes out and the oxygen dissolved in water .The skin is always kept wet by the surroundings water.The mucus secreated by the epidermal slime glands also prevents it from drying on exposure.

Sunday, 5 August 2012


Balantidium is a trichostomatid ciliated parasite,inhabiting the intestine of man,pigs,sheep etc. They are present in large numbers in the rectal contents of frog.The organism is large and ovoid and measures about 60-70mew. The entire outer surface is covered by longitudinal,slightly spiral rows of cilia. At the anterior end is a vestibule leading to the cell mouth or cytostome. it is lined by longer cilia. The cytoplasm includes two contractile vacuoles a macronucleus and food vacuoles. Nutrition is holozoic and the undigested residue is left by cytopyge.Reproduction takes place by asexual binary fission .Infection takes place through cysts in contaminated food and water


Friday, 3 August 2012


CHOANODERM-The gastrodermis consists of a single layer of flagellated cells,the choanocytes. The choanocyte is an ovoid cell with free end bearing a transparent contractile collar. The collar surrounds a single long flagellum which arises from a basal granule. The nucleus lies at the centre of its cell body . The choanocytes are used in feeding and for ensuring the flow of water within the animal,s body.

Wednesday, 1 August 2012


Chalina is a deep-water form and orange,yellowish brown or red in colour.The sponge is popularly known as the mermaid,s gloves" or "dead-man,s finger,s perforated with oscula. The skeleton consists of spongin with siliceous spicules embedded in it.When it is broken from its stalk and washed ashore it does not occur in shallow waters.

Sunday, 29 July 2012


Astraea or star-coral is a colonial coral with closely-placed polygonal cups bearing polyps. The thecae are so close together as to have common walls.The colony is compact and massive and produced by budding,the buds  growing more or less parallel with one another.The coenchyme is formed by calcifications of the coenosarc and gives origin to individual corallites. The polyps in cups are elevated rounded widely separated and spirally arranged.

Thursday, 26 July 2012


Teredo is commonly called as shipworm.It is a highly specialized marine bivalve which is very destructive to wood in sea water.The body is long and slender with a small anterior shell. The shell is used  for burrowing in the wood of ships.The foot is extremely reduced and acts as an adhesive organ for attachement to the wall of its hole-habitat. The mantle cavity bears paired and elongated gills and gonads. The inhalent and exhalent siphons are also elongated.

Wednesday, 25 July 2012


The pearl oysters are sedentary marine bivalves found in all seas except in colder .The indian pearl oyster is PINCTADA VULGARIS that is known  for yielding precious pearls. The two shells are unequals, with the left one comparatively larger than the right one and remain attached to a rock. The adductor muscles is single and large. The foot is lacking in the adult. Pearl is formed as a result of nacreous secretion from the mantle around a small particle.

Sunday, 22 July 2012

D D T(Dichloro-diphenyl trichloroethane),B H C

It is a white amorphous powder practically insoluble in water but dissolves in most organic solvents .D D T is used extensively safe.
B H C(Benzene hexachloride or gammexene)-It is white or chocolate-coloured power which is insoluable in water but soluable in organic solvents.It is used like D D T as spray for killing mainly the aphids on fruit and nut crops.

Thursday, 19 July 2012


It is commonly called as mussel shrimp.It is a small ostracodan crustacean.It bears in large numbers in stagnant ponds.The segmented body is completely enclosed in a protective bivalved carapace which makes it appear like a miniature clam.The anterior end of the body bears a large median eye.The antennules and the antennae are large and also help in swimming.The only appendages are two pairs of thoracic legs. It swims with the first pair of legs .The abdomen lacks appendages but ends in a pair of small caudal ramii. It is omnivorous, feeding on small organisms and detritus. The females are common and their eggs usually develop parthenogenetically as males are not known in certain genera.


Lepas commonly known as ship or goose barbacle.It is a stalked crustacean.It is found as in seas attached by a peduncle to wooden ships.The peduncle is highly movable and the oral end of the body contains the vestiges of the antennules.The proper or capitulum is protected by a bivalved mantle or carapace which is further strengthened by five large calcareous plates-two proximal scuta,two distal terga and a single dorsal carina.The larva is cypris which after a free swimming period settles to the bottom and growth into the stalked adult.The ventral mantle opening are protruded six pairs of delicate filament like or cirriform thoracic appendages .They feed upon minute organisms gathered from the water by the thread like feet and kicked into mouth.The lepas is hermaphrodite.

Wednesday, 18 July 2012


Hippa,commonly called as mole crab.It is found in the sand near the coasts. The body is oval with a large more or less cylindrical cephalothorax with carapace.The head bears a pairs of stalked compound eyes, a pair of short antennules and a pair of long antennae bearing hairs on the hinder surface.The rostrum is very much reduced .The five pairs of walking legs are thoracic and adapted for digging,being curved and flattened.The first legs are chelate.

Monday, 16 July 2012


It is commonly called rock barnacle.It is marine crustacean found attached to rocks, shell of hermit crabs.The mantle surrounding the body is covered by six calcareous plates an unpaired carina unpaired rostrum and two pairs of lateral plates.The opening of the mantle is provided with the fourfold lid,consisting of two  scuta and two terga.There is six pairs of delicate ,fringed legs. In water this legs propel food to mouth .When the tide is out the mantle plates close for protections. Rock barnacles are serious pests on the bottom of ships.


The sting of apis is modified ovipositor and is used for injecting poison.It is composed of two straight grooved stylets or lancets.The muscles associated with the sting help in the operations of the lancets and a set of three chitinous plates on either side acts as levers to move the barbs.The poison glands secreats the acidic materials that is stored in a sac like poison sac located at the base of the sting.There is associated alkaline gland that secreats alkaline materials. The two materials mix to form the poison or bee venom that flows down the sting into the wound of the victim .After performing there duties the workers bee leaves the sting apparatus and dies.

Sunday, 15 July 2012


Amoebiasis,also known as amoebic dysentery,is caused by Entamoeba histolytica. Its trophozites, that penetrate the wall of the intestine secrete histolytic enzymes and feed upon its cells causing the formation of ulcers. The trophozoites under certain cirumstances reach the liver and brain also causes abscess formations.Transmissions of the parasites from man to man takes place through tetranucleate cysts.The trophozoites changes into a smaller minuta cyst.Amoebic dysenteries is endemic in warm countries.These cysts are foivoided with the faecal matter and contaminate food and water and spread into new hosts.

Saturday, 14 July 2012


Three kinds of individuals or castes 1>WORKERS-Which are strile females.
2>drones-Which are fertile males.
3>Queen-Which are fertilefemales.
The workers have job of producing the royal jelly, building the bee hives, caring the larvae and disposing of the debris and dead bees. The drone and queen are used for reproductive purposes.The average sized colony conists of one queen, about 100 drones and 60,000 workers.

Friday, 13 July 2012


The mouthparts of honey bee are of chewing and lapping type.The labrum lies below the clypeus and the mandibles are situated on either side of the labrum. The labrum are used for moulding the wax and manipulating the pollen.The glossae of the second maxillae or labium form a tongue-like process or ligula with a spoon like depressions at its tip called the labellum or honey spoon. It constitutes a tube or proboscis for sucking up the nectar.The labial palps are well developed and they help to make the ligula. The apparatus is protected by the long galeae of the first maxillae.


VORTICELLA is a type of ciliate almost bell-shaped or campanulate with free anterior end surrounded by cilia.It is solitary and stalked ciliate often found in freshwater ponds,lakes rivers .There are 200 species all of which solitary.They occur in large groups but are never colonial. They can live only in uncontaminated waters where bacterial growth does not become too great.Some species are marine,or epizoic and are few parasitic.V.microstoma is the one which is more frequently seen in laboratory infusions.
SHAPE AND SIZE-It is bell-shaped asymmetrical body.The long contractile stalk. Both the body and the stalk are capable of great individual variations in size and form. The body of smaller V.microstoma measures 55 mew to 35mew. The largest species V.campanula in size with the lenght of 53 to 4150 mew.

Thursday, 12 July 2012


Respiration takes place by the diffusion of gases through the body surface.The gaseous exchance i,e intake of oxygen and giving out of carbondioxide takes place between the blood capillaries of the outer epidermis and the surface film of moistures contributed by secreated mucus excreated wastes and coelomic fluid.Haemoglobin dissolved in the plasma of blood acts as a respiratory pigments transporting oxygen to the body tissues.

Saturday, 7 July 2012


Two type of respirations-AEROBIC AND ANAEROBIC.
ANAEROBIC RESPIRATIONS-It works in the absent of oxygen.e.g tapeworm living inside the human intestines.It occur inside our own body i the fast-working skeletal muscles temporarily. During physical exercise like running,walking for long distance ,wrestling,weight-lifting,etc our muscles work too fast but not getting enough oxygen. In this situations the muscles are working in the absence of oxygen to provide extra energy. The product of anaerobic respirations in such  muscles is lactic acid. The lactic acid gives the feeling of fatigue.This conditions is called oxygen-debt.When you rest for some time this lactic acid slowly get oxidised by the oxygen and so debt is cleared.
AEROBIC RESPIRATIONS-It works in the presence of oxygen.
SHIVERING and CLATTERING of teeth-In winter when we feel cool this is emergency activity of the muscles cells to produce extra heat.

Friday, 6 July 2012


Respiration is vital process in all living organisms.It gones non-stop through out life.It is process in which the raw materials used ,the end-product used and the amount of energy liberated.So it is process in which the raw material used or the chemical process of releasing energy by breaking down giucose for carrying the life process.There is five points to be rembeber this part of respiration yielding energy occurs inside the living cells and hence it is better known as cellular or tissue respiration.
2>The breakdown of glucose to carbon dioxide and water does not occur in a single steps but in a series of chemical steps.some of the steps occur in cytoplasm and inside the mitochondria.
3>The breakdown of process is envolve the enzyme citrase kinase.
4>ATP release from the adenosine triphosphates first discovered by KARL LOHAMM IN 1929.We get energy in the form heat  in which adp first converted into ATP .It is also called as currency of energy in side the cell. One mole of glucose on complete oxidations yields 28 molecules of ATP.
5>The essensials steps of cellular respirations are same in plants and animals.
WHY WE NEED ENERGY-We need energy for a vast variety of activities in them.Some of these are:
1>Synthesis of protein from aminoacids.
2>productions of enzymes.
3>contractions of muscles for movements.
4>conductions of electricals impulse in a nerve cell.
5>By cell divisions formations of new cells.
6>For keeping the body warm i,e warm-bloded animals e,g birds and mammals.

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 .

Wednesday, 30 May 2012


The outer most cells on the skin surface are thin,dead and fully keratinised. They form a horny or cornified layer called stratum corneum. It is especially thick on soles and palms.The outer portion of this layer is constantly being worn away,the dandruff is a familiar .News cells are constantly added from when the granular cells become horny and die. This dead layer is tough ,prevents mechanical injuries and fungal and bacterial attacka,and reduces water loss from the body. The outer surface of epidermis contains minute openings of sweat glands and hair follicles.

Tuesday, 29 May 2012


Family tetrodontidae,order tetraodontiformes.commonly called globe fish or puffer.shape round or globose when taken out the water,it inflates suddenly with air like a balloon and a sound is emitted by forceful expulsion of air fromoesophagus. scales modified into small spines,especially on ventral side. mouth narrow,teeth fused to form beak.eyes large and protruding pelvic fins lacking.it contain alkaloid poisoncalled tetrodotoxin which is used in lung infection in japan.
DIODON-Family diodontidae,order tetraodontiformes. commonly called porcupine fish. occurs from red sea through indian seas to pacific ocean.Body uniformly covered by large movable spines for defence.
OSTRACION-FAMILYostraciontidae,order tetraodontiformes.Body roughly triangular and encased in a carapace or armour of hexagonal bony plates.commonly called trunk fish or coffer fish.due to presence of two horn like suptaorbitalspines called as cow fish.


The skin of rabbit is also built of two main parts -an outer epidermis and an inner dermis.
EPIDERMIS-It is the outer thin stratified epithelium developed from the embryonic ectoderm.The epidermis consist of malpighian layer and the superficial cornified layer.
(a)MALPIGHIAN LAYER-The malpighian layer,or stratum malpighii is divided into (1)SRRATUM GERMINATIVUM-The germinal layer is the innermost layer in contact with the basement membrane secreatedby the underlying dermis.Its cells are columnar,arranged in a single row one cell thick,and continually divide mitotically adding new cells to the epidermis

STRATUM SPINOSUM-Its lies above the germinal layer and is also called the transitional layer. It is several layer thick and made of polyhedral cells.these cells are gradually pushed outwards,they become flattened and keratinized due to deposition of a horny scleroprotein known as keratin.
STRARUM GRANULOSUM-The cells in the upper part of stratum spinosum form the granular layer containing keratohyalin granules. It is developed in parts of the body having thick epidermis such nas the palms and the soles.
STRATUM LUCIDUM-Above granular layer in palms ther is non-stainable layer of shiny and refracitle cells.

Monday, 28 May 2012


Family hemirhamphidae, order beloniformes. found in river and ponds of w.bengal and orissa. called as haif-beaked fish.lower dentaries projected beyond the upper jaw,both having pointed teeth.
ANABAS-family Anabantidae ,order perciformes.accessory respiratory organs of thin laminae in supra-branchial chambers,for breathing atmospheric air.travel on land by fins and opercular spines.
REMORA-Family echeneidae, order echeneiformes.size up to 50 cm.scales minute,head depressed and its upper surface bears a large,flat,oval adhesive discor sucker made by two rows of transverse lamillae.scales modified anterior fin. fish usually carried from place to place attached to body of largefish.naive captures sea turtles and fishes with a remora tied with a cord.remora eats smaller fishes.

Saturday, 26 May 2012


Belongs to family syngnathidae, order syngnathiformes.Size 5 to 20 cm. Found in tropical and temperate seas including Indian ocean commonly called sea-horse.
BODY- Head large at right angle,tubular snout,mouth toothless and suctorial. Tailed long ,prehensil and coiled around sea-weeds, gills lophobranchs made of several small rounded lobes.On the belly of male is a brood pouch for incubating eggs. On the belly of female is a small anal fin.
SYNGNATHUS- family syngnathidae,order syngnathiformes.45 cm long.structures and habits similar to those of Hippocampus,except that is non-prehensile and carries a small caudal fin,COMMONLY CALLED PIPE FISH.
FISTULARIA-. COMMONLY CALLED FLUTE FISH because of slender elongated eel -like body and long tubular snout.skin naked. mouth small,narrow with minute teeth.caudal fin present with middle caudal ray much elongated and supported by horny rays.


The single species of bowfin, amiacalva, is another large,powerful,predatory freaswater fish of north america. The head skeleton and scales are simplifedAND TAIL IS ALMOST HOMOCERCAL. It moves by undulation of body and the long dorsal fin.

Friday, 25 May 2012


Paddle fishes or spoonbills are large bizarre fishes with an intriguing. The great elongation of snout into a flat oar-like rostrum. It is used to strir food from muddy river bottom,paddle fishes are planktivores.

Thursday, 24 May 2012


There are 20,000 living species of bony fish.The teleostei comprising about 17,000 species.
LATIMERIA-They were dominant in devonian times about 280 million years.Dr.j.l.b smith of rhodes university named this "living fossil" Latimeria chalumnae. Latimer is blue-grey with irregular white spots and highly reflective golden eyes. size range 0.75 to slightly over 2 m.In the absence of claspers male latimeria achieve copulation is not know.It discovered in 1938 coast of south africa,crossopterygians are all extinct .
The skeletal elements of paired fins lobes resembled the priximal skeletal elements of tetrapod limbs.
skull was similar to that of earliest amphibians.
Fresh waters forms migrated from one body of water to another because they could use their air bladders like lungs.

Wednesday, 23 May 2012


Enlarged heads and pectoral fins.
Projecting spines from gill covering.
e.g pterois(scorpion fish)
Bottom dwellers.
Body flat, lying one side.
Head asymmetrical ,both eyes present on upper or dorsal side.
Dorsal and anal fins fringing body.e.g
Scales cycloid.
No air bladder.
Dorsal fins form a flat oval adhesive disc.
e,g echeneis or remora(sucker fish)
Strong jaws with a sharp beak.
Scales often spiny.
e.g diodon(porcupine fish),tetrodon(globe fish),ostracion(trunk fish)
Bulb like tip over head to lure prey into wide mouth.
luminescent organ present.
e,g antennarius(angler fishes)

Monday, 21 May 2012


Scales cycloid.
Pectoral fins large.
exocoetus ,cypselurus(flying fish)belone(garfish),hemirhamphus(half beak),belone(garfish).
Protective scales on body.
snout tubular with suctorial mouth.
swim bladder closed.
e.g hippocampus(sea horse),syngnathus(pipe fish),fistularia(flute fish)
Head depressed with plate-like scales.
Air bladder long and without duct.
Accessory respiratory organs present.
e.g ophiocephalus or channa.
Body elongated,e,g eel.
Gill slits join to form ventral slit.
Paired fins,air bladder lacking.
e.g amphipnous,symbranchus(eels).
Body eel-like.
nostrils on tubular tentacles at end of snout. e,g mastacembelus,macrognathus.
Fin spines present.
Dorsal fins weberian apparatus absent.
Air bladder with out duct.e,g lates(bhetki)


Mouth opening terminal,small.
Scales cycloid,ctenoid or absent.
Tail fin homocercal.
 A hydrostatic swim bladder usually present.
Advanced or modern ray-finned fishes.
Scales cycloid.
Head and operculum not scaled.
Fins without spines.
Tail fin homocercal.
Pelvic finsabdominal.
Air bladder withopen duct to pharynx.
No auditory vesicles.
e.g clupea,salmo sardinops esox notopterus.
Deep sea forms with phosphorescent organs.
Mouth wide with minute teeth.Swim bladder absent. Dorsal and anal fins with claspers.
Air bladder with duct to pharynx. ossicles present between airbladderand internalear.
e.g labeorohita clarius wallago electrophorus.
Body long and slender,snake-like .
Scales absent.
Dorsal and anal fins long .
Pelvic fins present.
Air bladder .
e.g anguilla muraena(moray)

Sunday, 20 May 2012


Mouth opening small.
Ganoid or cycloid scales.
Tail fin heterocercal.
Ray-finned fish, transitinal between CHONDROSTEI AND TELEOSTEI.
Thin, overlapping cycloid scales.
Snout normal ,rounded.
Long dorsal fin.
Scales rhomboidal ganoid in oblique rows.
Snout and body elongated. e.g Lepidosteus or lepisosteus(garpike)

Friday, 18 May 2012


Paired fins thin,broad, without fleshy basal lobes, and supported by dermal finrays.
One dorsal fin, may be divided.
Caudal fin without epichordal lobe.
Olfactory sacs not connected to mouth cavity.
Popularly called ray- finned fishes. divided into three infraclasses or super orders CHONDROSTEL HOLOSTEI AND TELEOSTEI.
Mouth opening large.
Scales ganoid.
Tail heterocercal.
e.g ray-finned fish or cartilaginous ganoid.
Rhomboid ganoid scales and pectrol fins.
Dorsal fin of eight finlets.
Ossified skeleton.
e.g polypterus(bichir)
Scales less .
Skleton cartilaginous.
e.g acipenser(sturgeon), polyodon(paddlefish)


Paired fins leg-like with a fleshy,bony central axis covered by scales.
Dorsal fins.
Caudal fin hreterocercal with an epichordal lobe.
Olfactory sacs usually connected to mouth cavity by internal nostrils or choanae.
Fleshy or lobe-finned or air breathing fish.
Divided into two superorders .ORDER 1. CROSSOPTERYGII
Paired fins lobate.
Caudal fin three lobed.
Premaxillae and maxillae present.
Internal nares present or absent.
Spiracles present.
Air bladder vestigial.
Primitive fleshy-finned extinct fishes. Latimeria. ORDER 2. DIPNOI
Median fins continuous to form diphycercal tail.
Premaxillae and maxillae absent.
Internal nares present and spiracles absent.
Air bladder single or paired,lung like e.gEPICERATODUS,PROTOPTERUS LEPIDOSIREN.

Thursday, 17 May 2012


It includes true bony fishes.There include 20,000 living species,both freshwater and marine. Some of the freshwater forms are the carp,perch,bass, trout,catfish,sucker. Where as marine fishes are the tarpon,meckerel,tuna,sailfish,barracula,flyingfish. The classification of class osteichthyes by A.S.ROMER(1966) . The two subclass include sarcopterygii and Actionpterygii.The subclass Teleostei include 17,000 species the singke largest group of living vertebrates.

Wednesday, 16 May 2012


Cloaca lacking.
Anus absent.
Respiration by four pair of gill on bony gill arches, covered by a common operculum on either side.
Ventral heart
Sinus venosus and conus arteriosus present.
Adult kidneys mesonephric.
Excretion ureotelic.
Brain with very small olfactory lobes, small cerebrum and well developed optic lobes and cerebellum.
Cranial nerves 10 pairs.
Well developed lateral line system.
Internal ear with three semicircular canals.
Sexes seperate.
Gonads paired.
 Fertilization usually external.
Mostly oviparous,rarely ovoviviparous or viviparous.
Eggs minute to 12 mm.
Cleavage meroblastic.
Development direct, rarely with metamorphosis.
Claspers absent.

Tuesday, 15 May 2012


Inhabit all sorts of water-fresh,brackish or salt warm or cold water.
Body spindle-shaped and streamlined.
Fins both median and paired ,supported by fin rays of cartilage or bone.
Tail usually homocercal.
Skin with mucous gland,usually with embedded dermal scales of 3 types ganoid,cycloid or ctenoid.
Placoid abescent.
Endoskeleton chiefly of bone.
Claspers absent.
Mouth terminal or subterminal.

Monday, 14 May 2012


Mature ovaries or testes can be identified only in sections because of the different structure of spermatozoa and ova they contain. The testes present a streaky appearance due to presence of spermatozoa. The mature sperm of branchiostoma one of the smallest among chordates in length. It consist of the nucleated head with acrosome a middle piece and a long tail. The ovary contain ova which are large and some what rounded cells each 0.i mm in diameter and having a large nucleus. They are microlecithal or poor in yolk content. Gonoducts are abesenr. Mature gametes are discharged into the atrium by rupture or dehiscence of gonadial wall along certain waeker spots called cicatrices which after wards close. The gametes so liberated escape through atriopore with the outgoing water current.

Sunday, 13 May 2012


In amphioxus the two sexes are separate but there is no sexual dimorphism as male and female individuals look identical.
GONADS-The adult has 26 to27 pair of similar gonads arranged metamerically in two rows,one pair in each segment from 25 to 51. The gonads are situated ventro-laterally from middle of pharyngeal region up to the atriopore. They are visible through the transparent bodywall arranged in a linear series . Gonads are simple hollow sacs mesodermal in origin and bulginginto atrial cavity. They are covered on the outer side by the bodywall and on the inner side by the atrial epithelium. Gonads contain an outer secondary gonadial cavity around an inner primary gonadial cavity surrounding a group of germ cells which arises from its wall.
DEVELOPMENT-Fertilization and development take place externally in sea water .

Friday, 11 May 2012


These are sensitive to internal stimuli such as contractions of muscles.The exteroreceptors there are also present some enteroreceptorsin the form of free nerve ending in muscles.


Sensory cells scattered all over the epidermis,especially on the dorsal side. Groups of sensory cells or papillae are present on oral cirri and velar tentacles. These are chaemoreceptors and tactile organs.

Thursday, 10 May 2012


It is located at the floor of cerebral ventricle . It consists of a patch of tall ,columnar and strongly ciliated epitheliar cells. The exact function of infundibular orgain is uncertain. The various function assigned are detection of pressure in the cerebro-spinal fluid perceiving the shadow cast by cephalic pigment spot or neurosecretion.

Wednesday, 9 May 2012


It is a depression of ciliated ectodermal cells on the roof in the anterior region of cerebral vesicle. The area where larval neuropore closes when the adult neural tube is formed. It lacks sensory cells but it is considered anolfacrory chaemoreceptor due to its position corresponding with the single nostril of cyclostomes.

Monday, 7 May 2012


The pit and groove of  Hatschek present in the roof of oral hood are considered sensory organs of unknown function.


It is large pigmented spot on the anterior wall of cerebral vesicle. It is act as cerebral eye. but it lacks a lens and is also not photosensitive. It is supposed to shield the ocelli from any frontal stimulation by light and probably acts as a thermoreceptor.

Sunday, 6 May 2012


The  Peripheral nervous system includes paired nerves from nerve cord.The two pair arising from cephalic vesicle are called cerebral nerves. They lack ventral roots. They are sensory in nature and convey impulses from receptors of snout, oral hood and buccal cirri to the nerve cord.The nerves arising from nerve cord behind the cerebral vesicle are called spinal nerves. Each pair of spinal nerves actually includes separate dorsal and ventral nerve roots .Dorsal nerve root is both sensory and motor and passes out to skin between myotomes. The ventral nerve root is motor and opposite to the myotome .The dorsal and ventral roots of a pair do not originate at the same level and the dorsal root of one side lies opposite the ventral root. The dorsal root is single the ventral root is made of several branches. Nerves of amphioxusare primitive and non-myelinated is not covered by a sheath of myelin in the vertebrates.
OCELLI-These are photoreceptors or light-sensitive organs on the ventro-lateral sides of nerve cord. They are originated in different directions and help the animal in burrowing in sand or in swimming spirally to perceive light from all directions. The eye spot or ocelli is made up of two cells an outer pigment cell or melanocyte and inner photosensitive cell with a striated apicalborder which serves as a lens. The photosensitive cell sends a fine nerve fibre to the nerve cord.

Friday, 4 May 2012


The central nervous system of Branchiostoma includes a hollow dorsal neural tube or nerve cord lying mid-dorsally . It has no ganglia. Its anterior end terminates in the rostrum. It has slight enlargement brain called cerebral vesicle. The posterior part called the spinal cord. The narrow canal called neurocoel. It dilates within the cerebral vesicle forming its ventricle.At the roof arise pouch -like blind dorsal diverticulum that extends behind the central canal. The cerebral vesicle contains two receptor organ a pigment spot infundibular organs on its floor. It consists of inner grey matter of nerve cells surroundings the central canal and outer white matter of nerve fibres. These enables the animal to contract suddenely and violently in case of danger.


It consist of two nerve plexes in the gut wall connected to nerve cord plexes in the gut wall connected to nerve cord by visceral .The autonomous system control the involuntary muscles of the gut wall. Sympathetic ganglia are lacking.

Thursday, 3 May 2012


The nervous system is very simple. The well developed brain, as found in higher chordates is absent.

Wednesday, 2 May 2012


The two sac like brown funnel are situateddorsally upon the posteroor end of pharynx. The narrow anterior end of each funnel opens into the epibranchial or dorsal coelomic canal of its side.. Most the funnel where the excretory while of to be receptor organs.    

Thursday, 19 April 2012


The cells are present on the floor of atrial cavity form renal papillae which are probably also excretory in function.

Wednesday, 18 April 2012


They closely resemble the protonephridia of flatworm providing good example ofparallei evolution. Some other organs and cells are also shows excretory systems.

Tuesday, 17 April 2012


Lymph as such is lacking.The so-called lymphatic spaces or sinuses present inside fins and metapleural folds, are called filled with colourless blood lacking in leucocytes. It is the oxygen required by the animal is obtained by the gaseous exchange between outside water and blood inside these superficial sinuses.

Monday, 16 April 2012


Blood flows anteriorly inside parietal ,subintestinal and posterior cardinal veins and ventral aorta. It flows posteriorly inside lateral and median dorsal aortae and anterior cordinal vein. The course of circulation can be graphically represented .

Sunday, 15 April 2012


Bloodfrom dorsal body wall is collected by a pair of parietal veins one on either side. They run above the intestine for some distance and the turn ventrally to join the sinus venous.

Saturday, 14 April 2012


The blood from ventrolateral region is collected on either side by an anterior and a posterior cardinal vein. The two unite just behind the pharynx to form a common cardinal vein or ductus cuvieri. The two ductus curieri then run down through the atrium to join the sinus venosus.

Friday, 13 April 2012


The subintestinal vein continue anteriorly as the hepatic portal vein running ventrally along up in the midgut diverticulum into which it breaks up in a capillary network. Blood is collected by a hepatic vein running along its dorsal border and bending downwards to join the sinus venosus. Hepatic portal system occuring for the first time in Branchiostoma is a precursor of that of higher chordates.

Tuesday, 10 April 2012


The blood from tail region is collected by a mid-ventral caudal vein and from intestine by lateral intestinal veins. These join a small median longitudinal subintestinal vein lying below the intestine in the form of a plexus. Blood flows in it anteriorly.


It is a large median longitudinal artery extending forward from sinus venosus. It is mid-ventrally in the wall of pharynx below the endostyle in the subendostylar coelom, also called as subendostylar aorta. Blood flows in it anteriorlydue to rhythmic contractions of its muscular walls. The ventral aorta gives off a series of a paired lateral afferent branchial arteries . The afferent vessels leave the pharynx the pharynx dorsally as in the form of efferent branchial vessels which opens into a lateral dorsal aorta of that sac. The vessels splits into a small capillary network the nephric glomerular sinus or glomus in relation with a nephridium.

Sunday, 8 April 2012


It is small, thin-walled sac present below the posterior end of pharynx . Blood from different parts of the body is collected by sinus venosus through a number of veins and pumped forward into the ventral aorta.

Saturday, 7 April 2012


Branchiostoma is closed type blood vascular system. Blood is colourless due to lack of any respiratorypigment and corpuscles. Blood vessels in some lymph spaces such as in metapleural folds and the dorsal and ventral fins. Its main tobe the transportation of food and excretory products rather than oxygen and carbon-di-oxide for gaseous exchance.There is no structural differences between arteries and veins due to their homologies with blood vessels of higher chordates.


The pharyngeal wall of branchiostoma is richly vascular and the warer current entering the pharyngeal cavity brings fresh oxygen. The blood flows so close to the surface that some exchange between carbon-di-oxideof blood and oxygen of water can easily occur. There is no capillary network in gill bars. The blood lacks a respiratory pigment. Many workers questions about the respiratiory role of pharynx. It is probable that most gaseous exchange occurs through superficial areas such as fins, metapleural folds and atrial wall containing lymph spaces.

Friday, 6 April 2012


.Digestive enzymes are secreated from two source ,midgut diverticulum and the midgut epithelium. The food cord from pharynx passes through oesophagus into midgut. Digestion starts in the midgut by ciliary action. In the ilio-colic ring, the food cord undergoes rotation due to ciliary activity. This breaks up the food material into still smaller particles, throughly mixes up enzymes with food and delays the backwards passage of food to allow more time for action of enzymes.Digestion is mainly extracellular but intracellular digestion also takes placewhich is unique as it isunknown in other vertevrates. Intracellular digestion takes place mainly in thephagocytic cells of midgut diverticulum. Some food particles may pass into atrial cavityand eventually engulfed by the phagocytic cells present in renal papillae on the floor of atrial cavity.

Thursday, 5 April 2012


Branchiostoma is a ciliary or filter feeder, like an ascidian. The animal leads a sedentary life buried in sand .Food particles are filtered from the current of water entering pharynx through mouth and finally going out through atriopore.The atriopore closes and the transverses muscles oc the floor undergo sudden contraction. This sets up a reversal of water current or rejection current ejecting out forcefully through through the enterostome and mouth. Pharynx plays the most important part in food collection. In side pharynx the food particles get entrapped in mucus secreted by the glandular tracts of endostyle and by pharyngeal epithelium. The endostylar cilia and the frontal cilia of gill bars beat upwards so that mucous sheets laden with food particles move dorsally to the epipharyngeal groove. The cilia of epipharyngeal grrove beat backwards moving the food-laden mucus into the oesophagus in the form of a narrow food cord.

Tuesday, 3 April 2012

branchiostoma-physiology of digestive system

FOOD-Branchiostoma is a microphagus animal feeding on diatoms,desmids,protozoans and pelagic microscopic organisms, in sea water.


The midgut diverticulum reffered to as''liver''s the main digestive gland.It  arises as  a blind pouch from the ventral oesophagus and midgut. It is surrounded by a narrow coelomic cavity. Its inner lining has a strong ciliated groove for movements of food. Its zymogen cells secrete a number of digestive engymes. The epithelial lining of intestine also contains glands cells that secrete digestive enzymes.

Monday, 2 April 2012


It is a small circular aperture controlined by a sphinter.It opens at the base of caudal fin a little on the left side of the mid-ventral line.

Saturday, 31 March 2012


The gut is long as the pharynx .It is suspended from the dorsal bodywall by a dorsal mesentery into the atrial cavity. It is covered by a thin layer of smooth muscles and its internal epithelial lining has several ciliated tracts. The intestine can differentiated into three parts midgut. The large blind pouch or diverticulum arises from the juctions of oesophagus and midgut. The lining of midgut on the right lateral side bears a crescentic lateral ciliary tract. Its cilia beat downwards directing food into the midgut diverticulum. Midgut is followed by a densely ciliated ilio-colic ring .The hind gut is narrower.The terminal part or rectum is heavily ciliated and opens to outside by anus.

Friday, 30 March 2012


The pharynx opens into a short narrow and tubular oesophagus having ciliated internal lining and leading into the gut.

Wednesday, 28 March 2012


These are a pair of narrow ciliated tracts from the anterior end of endostyle. They are upward and one along the lateral wall of pharynx to unite dorsally with the anterior end of epipharyngeal groove. These bands are a small ,antero-dorsal prebranchial region of pharynx devoid of gill-slits.


The hyperpharyngeal is aprominent ciliated groove present mid-dorsally along the roofof pharynx. It runs upto the oesophageal opening.

Monday, 26 March 2012


The hypobranchial tract extends mid ventrally the entire floor of pharynx. It forms a shallow groove with four longitudinal tracts of mucus-secreating gland cells with five tracts of ciliated cells. The cilia of the median tract are the longest. The endostyle is supported below by two gelatinous skeletal plates under which is present the sub-endostylar coelomic canal contaning the ventral aorta.


The pharyngeal gill bars are of two type primary and secondary- The skeletal rod pf a primary gill bar is called primary gill rod . Its lower end is forked and it encloses a blood vessel and a coelomic canal through out its length. The secondary gill bar develops a small tongue bar which grows downwards from the dorsalwall of a primary gill slits. The skeletal rod  of a secondary gill bar is called secondary gill rod.The primary gill bars are interconnected by a system of transdverse  bars or synapticula which impart a basket like appearance to the pharynx similar to the branchial sac of tunicates. A synapticulum also contains a blood vessel and a skeletal rod.

Friday, 23 March 2012


The lateral walls of pharynx are perforated by 150-200 pairs of closely and obliquely set narrow and vertical opening called branchial apertures gill-slits or gill-clefts. The gill-slits bear no gill and their number increages with the age of the animal on the posterior .The portion of pharyngeal wall between two gill slits is called a branchial lamella or gill bar. Gill bar consists of a ciliated epithelial covering both ectodermal, enclosing a mesodermal core containing fibrous connective skeletal rod.


Pharynx is a very large, spacious and compressed chamber forming the largest part of alimentary canal. It occupies nearly one-half anterior part of body and suspended in the atrial or peribranchial cavity which surrounds it on all sides except the dorsal.

Thursday, 22 March 2012


The vestibule is closed by a circular ring-like vertical membrane the velum. It is perforated by a central circular aperture the enterostome. The enterostome is erroneously called mouth .The true mouth opens intostomodaeum lined with ectoderm. The velum is provided with a sphincter to open or close the enterostome. The posterior border of velum is prouced into 10 to 12 slender , ciliated and sensory velar tentacles.They also serve to strain the water current entering through the enterostome.

Wednesday, 21 March 2012


The epithelial lining of oral hood forms 6 to 8 pairs of finger -like folds each formed by a ciliated groove bounded by a ciliated  ridge. Collectivelty these are called as wheel organs or muller's organs. In rotifers the cilia of wheel organ set up a vortex or whirling water current to sweep food organisms into mouth. The mid-dorsal groove is the largest which ends in a small depression on the roof of buccal cavity. These are called Hatschek's groove and Hatschek's pit. Both are ciliated ,glandular and secreate mucus while the pit is considered a sensory organs .

Monday, 19 March 2012


The oral hood encloses a large funnel-shaped cavity or vestibule into which opens the mouth. The cavity is lined with ectoderm, and is regarded as stomodaeum and its external opening the true mouth.


In branchiostoma 10 to 15 pairs of stiff slender and ciliated oral or buccal cirri are present which bears sensory papillae. Their number increase with age. The buccal cirri and the edge of oral hood supported by stiff, gelantinous skeletal rods. The buccal cirri form a sieve to filter entry of large particles with food current.

Sunday, 18 March 2012


The oral hood is formed by the dorsal and lateral projections of the anterior end of trunk.

Friday, 16 March 2012


Mouth is large oval median aperture situated below the rostrum tip of the trunk. It is bordered by a frill-like membrane , the oral hood.

Thursday, 15 March 2012


The alimentary canal is a straight and complete tube from mouth to anus.It is lined by ciliated epithelium and diameter varies in different parts.

Wednesday, 14 March 2012


The digestive system consists of an alimentary canal and digestive glands.

Tuesday, 13 March 2012


The atrial is large body space other than coelom. It is formed by a pair of metapleural folds,on either side above the gill-slits of embryo,growing downwards and united ventrally by a transverse folds. In branchiostoma the gill-slits open intothe atrium and not directly to the exterior as in other chordates.The atrium projects into each dorsal coelomic canal on either side of pharynx forming the brown funnel or atriocoelomic canal whose function is unknown. The atrium projects the delicate pharyngeal region.

Sunday, 11 March 2012


The body cavity in branchiostoma is true coelom lined with somatic and splanchnic layers of mesoderm and filled with a lymph like coelomic fluid. It is enterocoelic in origin. The pair of dorsal longitudinal coelomic canals are present. A mid ventral longitudinal subendostylar coelomic canals running through the primary gill bars.Besides small coelomic spaces are also present within the gonads and around the midgut or liver diverticulum.


These include
a) fin-ray boxes
b) oral ring
c) gill-rods
d) endostylar plates
e) tough fibrous connective tissue.

Friday, 9 March 2012


The axial endoskeleton notochord are called chorda dorsalis. It is elongated ,narrow ,cylindrical rod-like structures from tip to tail. It lies mid-dorsally at gut and nerve cord. The notochord  is surrounded by a laminated fibrous connective tissue notochordal sheath covered by a thin elastic membrane. The elasticity of notochord bending body movement but its rigidly prevents shortening of body when longitudinal muscles contract locomotion.

Thursday, 8 March 2012


has no skeleton. A number of endoskeletal structures are present. They are neither bony nor cartilagnious.

Wednesday, 7 March 2012


The muscles lying beneath the skin form the part of body wall. They are thick in dorso-lateral regions.They length of body present ina series of v-shaped myotomes or myomeres. The pointed apex of the vis anteriorly. In B.lanceolatum 60-62 myotomes are present. Myotomes are enveloped in a thin connective tissue layer . Due to their peculiar arragement several myotomes and myocommata . The myotomes help in lateral undulating movements of body as they can be twisted .Their contractions help in driving water of atrival cavity out of the atriopore.

Tuesday, 6 March 2012


The muscle layer is lined internally by a thin layer of parietal paritoneum. It is not continuous in the pharyngeal region .

Monday, 5 March 2012


The lateral side of body a series of muscle bands,called myotomes or myomeres. Between mouth and atriopore present on either side below the myotomes gonads.

Sunday, 4 March 2012


The body wall includes from outside- A thin delicate and transparent skin .
A well-developed musculature.
A parietal peritoneum.