LECTURE NOTES ON SALIENT EATURES OF PHYLUM ROTIFERA

Rotifera are, popularly known as “wheel animalcules" due to  their peculiar movement similar to the rotation of a wheel. They are actively swimming,microscopic aquatic animals, most common in freshwater habitats, such as ponds, lakes, streams, marshes .films of water, etc. Some are marine. Majority of them are benthic forms, but a few are planktonic species. They are relatively short living, and their life span ranges between a few days and a few weeks. They are well adapted to to withstand desiccation and to survive drought and hostile climatic conditions. Therefor they live in moist or partially wet terrestrial habitats, such as the cracks and crevices of rocks, fissures on land, etc. Rotifers are bilaterally symmetrical. unsegmented and pseuclocoelomate metazoans, with ciliated trochal  disc, syncytial epidermis, complete alimentary canal, specialized jaws, muscular pharynx and flame bulb type nephridia, and without circulatory  and respiratory organs. The salient features of the phylum are the following: .

(i) They have microscopic body  partially differentiated into head, trunk and tail or foot.

(ii) Anterior head region is broad with a  central disc, called apical field,which  is encircled by a ciliary zone, known as corona (rotatory organ or wheel organ. Corona may be partially subdivided into retractile, locomotor and food collecting discs called trochal discs.

(iii) Body is covered by a cuticle, formed of a glycoprotein, without-chitin or collagen. The cuticular covering sometimes becomes a hard and thick encasement, called lorica.  Organism with lorica are called loricates. and those without lorica are called illoricates.

(iv) Epidermis is mostly syncytial, except in the region of corona.

(v) Peri-visceral cavity is a spacious pseudocoel.

(vi) Pharynx is modified into a muscular mill, called mastax which  is provided with a masticatory apparatus or dental mill .Phrynx is   composed of hard and jaw-like cuticular structures called trophi or internal jaws. Mastax and trophi are characteristic of rotifers.

(vii) They  are ammonotelic. Excretory organs are protonephridia with flame bulbs.

(viii) Nervous system consists of a bilobed brain and several radiating nerves.

(ix) Sexes are separate. Sexual dimorphism is distinct .Male being smaller and almost degenerate. Eggs are of two kinds, namely syngamic eggs and parthenogenetic eggs. The former develops through fertilization, and the latter through parthenogenesis  without fertilization. In some rotifers  males are less numerous than females. In still others, males are altogether absent, and reproduction is exclusively parthenogenetic.

 (x) Many rotifers have the powers for cyclomorphosis and cryptobiosis. Cyclomorphosis is the seasonal change in the form, shape and proportion of the body. Cryptobiosis or “hidden life” is a death-like state of suspended animation which protects the animal from adverse environmental conditions.

LECTURE NOTES ON Reproduction,development and life cycle in rotifers

Rotifers reproduce by both parthenogenesis and sexual reproduction. In the former.

ova develop without fertilization, where as in the latter ova develop only after fertilization.

Thus, in parthenogenesis, only the female parent is involved, but in sexual reproduction,

male and female parents are involved. Fertilization is intemal . Development is direct and external. Early cleavage is determinate and spiral.  Male rotifers hatch out as sexually mature adults. Hence they remain small-sized through out life. On the other hand, females grow to sexual maturity only after hatching. Life cycle of rotifers is highly interesting in that there is a cyclic occurrence of syngamic and parthenogenetic generations in tune with the cyclic seasonal changes. Generally, there are two kinds of females among rotifers, namely amiotic females and mictic females. Amictic females produce larger eggs which develop only parthenogeneti cally into amictic or mictic females: they cannot develop through fertilization. On the other hand, the eggs of mictic females can develop either by parthenogenesis or by fertilization. If these eggs are not fertilized, they parthenogenetically develop to males. if they are fertilized, they develop to amictic females.

Examples: Brachionus, Polyarthra, Asplanchna,Keratella. Cellotheca.

LECTURE NOTES ON MORICULTURE

Moriculture

The cultivation of mulberry is called as moriculture. They belong to family moraceae. The important species of mulberry cultivated in India is Morus alba .Loam type soil with neutral ph is ideal for cultivation .Cultivation is through seeds or stem cuttings

Planting systems

Major systems of planting are Pit system, row system, kolar system, strip system, angular system.

1.Pit system:- It is followed under rained condition with wider spacing. Instead of ploughing, pits of standard size are made. Equal quantities of organic manure, red soil and sand are placed in each pit. Three cuttings are planted in a triangle in each pit.

2. Row system :- It is followed under irrigated conditions. Ridges and furrows are made by ploughing. Cuttings are planted at equal distance. The crop is grown as bush type.

3. Kolar system:-, Similar to row system. Space between plants is very much less. This system is followed in kolar district of karnataka. Hence known as kolar system.

4. Strip system:-  Mulberry is grown in strips of 2-3 rows. Each adjacent strips are separated by a wide distance. Distance between each plant  within the row is 15 cm. It is followed in west bengal.

5. Angular system:- Mostly followed in hill regions of nilgiris. Distance between plants is similar to pit system. Plants in adjacent rows are planted in such a way they form a triangular shape. It allows more plants per unit area.

Maintenance of mulberry garden

 Irrigation, Pruning,  Harvesting

Irrigation- Judicious use of water for maximum production is important. During dry period, irrigation should be given at 7 to 15 days interval. For loamy soils–once in 10 days.  For clayey soils – once in 15 days

Pruning:- Periodic cutting of branches for ensuring a good yield of quality leaves is known as pruning.

Objectives of pruning:- To maintain a convenient height, shape and size of the plant. To induce more vegetative growth. To synchronize leaf production with leaf requirement. To extend leaf production period. To remove dead and defunct wood. To expose plant for better sunlight and aeration.  To make cultural operations easier.

Types of pruning:-

Low cut pruning : it is widely practiced in japan. Plant is cut at a level less than 0.5m above ground level.

Medium cut pruning : plant is cut at a height of 0.5 to 1.5 m above ground level.

High cut pruning : plant is cut at a height of more than 1.5 m above ground level.

 Harvesting:-

Leaf harvested during afternoon contain less water and more of carbohydrates due to active photosynthesis and transpiration. Leaf harvesting in early morning hours is recommended

 Methods of harvesting

1.leaf picking :- Leaves are picked individually from main stem with petioles. It starts 10 weeks after bottom pruning.It requires more labour and leaves wither  quickly.   

2. Branch cutting:- The entire branch is harvested. It is used to feed worms after third moult directly. It requires less labour and leaves retain succulence for longer period.

3. Whole shoot harvest:- The branches are cut to ground level by bottom pruning. The entire shoot is fed to leaves. Shoots are harvested at 10-12 weeks interval and 5-6 harvests are made per year.

LECTURE NOTES ON MULBERRY DISEASES

Mulberry diseases:-

Fungal diseases

White root rot

Causative organism: rosellinia necatrix

 Symptoms- Shedding of leaves, Feeble growth of leaf buds, White mycelial patches on stump of the diseased plant, Root  rots

Control measures:- Diseased plants should be uprooted and burnt, Soil should be sterilized by placing calcium cyanamide in one-metre-deep holes, Use of antagonistic fungi like trichoderma and gliocladium in the soil, Disease free mulberry saplings should be used for cultivation

Mulberry trunk rot

Causative organism: Poliporus hispidus  and Gonoderma applantum

Symptoms:- Drying and rotting of the twigs and branches, Heart wood of the twig is destroyed

Control Measures:- Cuts or wounds in the plants should be covered with a fungiside. The affected branches should be cut and burnt

Wilt disease

Causative organism: sclerotium rolfsii

Black fungal patches appear on the cuttings. The sprouted shoots suddenly wilt and the cuttings die

Control measures:- Use of fungicides like bavistin , Spraying of antagonistic fungi Trichoderma harzianum

Powdery mildew disease

Causative organism: Phyllactinia  corylea.

White powdery patches appear on the ventral surface of the leaves. Affected leaves become dry, leathery and fall off.

Control measures:- Using wide spacing during initial plantation, Picking and burning of diseased leaves, Spraying morestan spray or karathane spray, Release of predator, yellow and white spotted lady beetles.

Bacterial diseases

Leaf blight disease

Causative organism: pseudomonas mori

Symptoms:- Small, water soaked irregular spots appear on the lower margins of the leaves. Affected young leaves become wrinkled and curl outwards. The lesions are dark,irregular,sunken and excrete bacterial ooze.

Control Measures:- Close spacing is to be avoided, Disease resistant varieties should be chosen for planting, Diseased plants are removed and burnt.

In vitro, the bacteria are controlled by streptocycline, streptomycin sulphate and streptopenicillin.

LECTURE NOTES ON PARASITIC ADAPTATION OF FLATWORMS

Adaptation
Adaptation is the fitness of an organism to its environment. It is the characteristic which results in suitable and convenient morphological and functional correlation between an organism and its environment.
Parasitic adaptations
The parasitic flatworms, the trematodes and cestodes, have undergone profound adaptations to suit their parasitic mode of life. These adaptations, termed parasitic adaptations in such cases, arc of morphological as well as physiological nature.
A. Morphological adaptations
1. Body covering, The thick tegument, frequently provided with scales, affords suitable protection to the parasite. It is probable that this thick protoplasmic layer is continually renewed by the cells
forming it.
2. Organs of adhesion. For a firm grip on or in the host’s body, some special organs of adhesion are necessary. The flatworm, for this purpose, are variously armed with suckers, hooks and spines.The suckers themselves may be with or without hooks and spines.
3. Organs of locomotion. Locomotion is actually an effort for procuring food. But parasites habitually inhabit such places in the host’s body, where suflicient food is available without effort. Thus, the
organs of locomotion, such as the cilia of free-living turbellarians, are absent in the parasitic forms. It is interesting to note that the locomotory organs are duly present in free-living larvae of parasitic forms; the miracidium possesses cilia and the cercaria possesses a tail for locomotion.
4. Organs of nutrition . Food of the parasite comprises the readily available digested and semi-digested food of the host. Elaborate organs for nutrition are thus not needed. Trematodes have an incomplete gut and, in most cases, a suctorial pharynx for sucking food. An eversible pharynx present in free-living turbellarians is absent in this case, asthe parasite has not to capture a large prey. In cestodes, the parasite freely bathes in the digested food of the host which is absorbed directly. There is thus total absence of alimentation in tapeworms.
5. Neuro-sensory system. Need for quick and efficient “response to stimuli” is associated with free active life and not with a quiet parasitic life in a safe environment. In parasites, therefore, there is profound reduction of nervous system and total absence of sense organs. Accordingly, the free-living miracidium possesses eye spots.
6. Reproductive system. It is the best developed system in helminth parasites, designed and perfected to meet the need for tremendous egg production. The parasitic flatworms, with a few exceptions like Schistosoma, are monoecious (hermaphrodite). Hermaphroditism is of distinct advantage to the parasite, because (i) it ensures copulation even when a few individuals are present (ii) after copulation
both the individuals lay eggs, thus doubling the rate of reproduction, and (iii) in the absence of a companion, the parasite can reproduce offspring. In cestodes, the reproductive system is much more elaborate; each mature proglottid possesses one  as in taenia solium) or two (e.g., Cotugnia, Maniezia, Dipylidium) complete sets of male and female genitalia. In a gravid proglottid all other organs of the system degenerate to make room for the uterus which becomes highly enlarged and branched to accommodate a large number of eggs.
B. Physiological adaptations
1. Protective mechanism: The alimentary canal parasites have to protect themselves from the action of digestive juices of the host. The tapeworms accom plish this (a) by stimulating the walls of the gut to secrete mucus, which then forms a protective clothing around the parasite, (b) by secreting anti- enzymes to neutralize the digestive enzymes of the host, and (c) by probably continually renewing their protective body covering i.e., the tegument.
2. Anaerobic respiration: Environment in the gut and bile ducts is devoid of freqoxygen. The flat-worms inhabiting these places, therefore, respire anaerobically by breaking down glycogen.
3. Osmoregulation: The osmotic pressure of the endoparasite’s body fluids, especially in case of trematodes, is almost the same as that of the host. This renders osmoregulation unnecessary. But in the intestinal tapeworm the osmotic pressure is a little higher. This permits ready absorption of host’s digested food by the parasite.
4. High fertility: Eggs produced by a parasitic flatworm face a very uncertain future. While passing through the complex life cycle, these potential off springs face several hazards as a result of which a very small percentage of the total eggs produced reaches adulthood. This threat to the very existence of the species is suitably met by the parasite which in its life time may produce eggs in millions. The reproductive organs of the flatworms, as already noted, are accordingly developed. Additional multiplicative phases in the life-cycle of some flatworms further increase the output of protential offspring. Several cercariae develop from a single miracidium of liver fluke and a single hexacanth of Echinococcus produces several scolices, each of which is a potential tapeworm.

Lecture notes on economic importance of corals

Decorative value:Some corals are highly priced for their decorative value.eg. fire coral, Pocillopora verrucosa and Acropora hemprichii

 Jwellery and ornaments:Precious corals like Corallium nobile or C. rubrum  are used in jewellery and ornaments.

Coral reefs and Islands:Corals are also important in building the coral reefs and islands, some of which are used as habitation by human and other animals.

Medicine:The organ pipe coral (Tubipora) is used in indigenous system of medicine in South India.

Building and road construction:Coral skeletons especially of species like porites are used in as building construction and for metalling the roads.

Preparation of lime mortar: Corals serve as raw materials for the preparation of lime mortar and cement because of their large calcium carbonate content.

Cement industry:Some older coral lime stones are rich in magnesium, hence they are of great value in cement industry.

 Barrier against sea erosion and cyclonic storm:Coral skeletons act as natural barriers against sea erosion and cyclonic storms.

Marine bird sanctuary:Old reefs have long served as sea bird sanctuaries .They  serve as  collection of huge deposits of guano( bird droppings).

Biodiversity:Coral reefs provide a unique habitat for large and diverse variety of plants animals and microbes.

Evolution:The richness and variability of the invertebrate fauna and the complex structure of the coral reefs have provided opportunities for the evolution of a number of fishes associated with coral reefs.

Tourism:In many countries Fringing reef, Barrier reef and Atolls are helping in the tourism industr

LECTURE NOTES ON FASCIOLA HEPATICA ( THE SHEEP LIVER FLUKE )

FASCIOLA HEPATICA ( THE SHEEP LIVER FLUKE )

Systematic position

PHYLUM-PLATYHELMINTHES

CLASS-TREMATODA

ORDER-DIGENEA

Distribution :It is distributed throughout the world. They cause liver rot disease in sheep.

Morphology: Its body is oval, dorsoventrally flat and looks like a leaf. Its body is soft and is 1.5 to 5 cm in length; 5 to 1.5 cm in width in the middle of the body. The body is pinkish in color. The digestive system is brownish colour because of the presence of ingested bile. At the anterior end mouth opening is present.On the ventral side above the ventral sucker a small genital openings is present. In the breeding season on the dorsal side a small opening of Laurer's canal is developed.At the posterior end a small excretory opening is present.At the anterior around the mouth an oral sucker is present. It is 1 mm. in diameter It is useful for ingestion and adhesion also.On the ventral side a ventral sucker is present 3 to 4 mm. away from anterior end. It is a large sucker. It is useul for adhesion.

T.S. of Body:

The body wall of Fasciola shows the following parts.

a) Tegument: It is an outer cytoplasmic layer. It shows microvilli. It is syncytial layer. It is thick. It contains mitochondria, endoplasmic reticulum etc. It contains sclero protein and is resistant to digestive juices. It shows backwardly directed spines.

b) Basement membrane: Below the tegument basement membrane is present.

c) Musculature: Below the basement membrane muscle layers are seen. The muscles are circular and longitudinal. Below the longitudinal muscles oblique muscles are also present.Below the muscles loose parenchymatous tissue is present. In this tissue various organs are enclosed. In this tissue, big mesenchyme cells are present. In this parenchyma all systems are included like digestive, excretory and nervous systems.

Digestive system: The digestive system is well developed.It distributes digested food to all parts of the body. At the anterior end of the body a mouth opening is present. It is surrounded by oral sucker. Mouth leads into buccal cavity, which leads into pharynx. Pharynx  is a thick chamber with glands. It leads into narrow oesophagus which  opens into intestine. This intestine is divided into branches. Each branch gives a number of irregular side branches. The two branches will end blindly near the posterior end of the animal. The intestine is lined by endoderm.These animals suck the tissue, fluid, lymph and bile from the host body. The digested food is distributed to all body parts of the branches of intestine. The tegument absorbs glucose from the host directly.

Excretory system : In liver fluke the excretion is carried on by flame cells. Liver fluke shows a big median longituidnal excretory canal with a number of branches and sub branches. The fine branches end with flame cells. These cells are hidden in the mesenchyme. The median longitudinal excretory canal opens at the posterior end through excretory opening.Each fell is irregular in shape. It is covered by thin wall. It produces branches which look like pseudopodia. The lumen of the cell is big and the nucleus is pushed to one side. In the lumen a group of flagella are present. They show movement. It looks like the flickering of a flame hence it is called flame cell.

From the mesenchyme the flame cells absorb the nitrogenous wastes and aminoacids. These wastes are pushed into the capillaries to which flame cells are connected. From there wastes enter into median longitudinal excretory canal and finally sent out through excretory pore.

Respiration:Fasciola hepatica lives in the bile duct of sheep as endoparasite. In this environment oxygen supply is very limited. Hence it takes up anaerobic respiration. The Carbon dioxide formed will be sent out through the body surface by diffusion.

Nervous system :The nervous system is well developed in Fasciola. On the dorsolateral sides of oesophagus two cerebral ganglia and a ventral ganglion are present. They are all united and a nerve ring is formed around the oesophagus.From the nerve ring 3 pairs of longitudinal nerve cords will arise. They are 1 pair on dorsal side,1 pair on ventral side and1 pair on lateral sides.The lateral longitudinal nerve cords are very long and well developed. They show transverse connectives. From the nerve ring and from all longitudinal nerve cords, fine nerves will go to all parts of the body.

Reproductive system:

Fasciola is a hermaphroditic or bisexual animal. It has both male and female reproductive organs.

a) Male reproductive system: The male reproductive system consists of a pair of a highly branched testis lying one above the other in the body. From each testis vas deferens arises. The two vas deferens or spermducts go forward and unite. The seminal vesicle is continued as an ejaculatory duct. It opens into the genital atrium which lies above the ventral sucker. The terminal part of the ejaculatory duct is highly muscular and known as the penis or cirrus. When not in use the cirrus is present in a sac called the cirrus sac.

b) Female reproductive system: The female reproductive system consists of a single highly branched ovary lying on the right side of the body. From the ovary oviduct arises which proceeds towards the centre of the body.On each side of the body two longitudinal vitelline ducts and a number of vitelline glands are present. They unite with longitudinal vitelline ducts through small ducts. The longitudinal ducts are connected by a transverse vitelline duct which is positioned a bit above the middle line of the body. From this transverse vitelline duct which is positioned a bit above the middle line of the body. From this transverse vitelline duct arises. This gives a median vitelline duct and it unites with oviduct. The combined duct opens into ootype. At the junction of the vitelline duct and oviduct a uterus arises. It is a long coiled tube. It opens into the genital atrium through female genital opening. At the junction of uterus, oviduct and vitelline duct, mehlis glands are present. The junction of the three ducts is called Ootype.During breeding season from this junction a temporary canal arises called Laurer's canal. It opens on the dorsal side of the body.