Why are infants kept on milk?

          The first kind of food a baby gets is mother’s milk. Why is this so?



          Milk is a highly nutritious food substance with which the female mammals feed their young. It contains most of the nutrients needed for growth and is, for most mammals, the main source of nutrition for several months after birth. In fact the milk of each species of mammals, including human beings, is a complete, wholesome and easily digestible food for its own young ones after their birth.



          Milk is produced in special glands called mammary glands. Most of the female mammals have teats or nipples from which their young can suck milk. These teats are connected to the mammary glands by a series of tiny ducts.



          Although the same ingredients are present in the milk of all mammals, their proportions vary. Milk is 80% to 90% water. It contains proteins, carbohydrates, fats, vitamins and minerals. These constituents are needed for growth and repair of bones and tissues and of the normal functioning of the endocrine glands which produce hormones for growth. Proteins (mostly casein and albumin) supply all the essential amino acids for growth and repair. The carbohydrates (mostly lactose or milk sugar) are a good energy source and help the body absorb calcium and phosphorus. The fats are in tiny droplets. Milk is converted into soft curd in the stomach of the young due to which digestion can proceed smoothly without the disturbance that fatty foods often cause. Milk also supplies vitamins A, B, C, D, E, K and niacin. These are needed for formation of healthy bones and tissues.



          If a mother takes diet rich in necessary nutrients, her infant will invariably receive all that he requires from her milk. This will also provide certain antibodies to help build immunity to diseases. Immediately after the birth the infant needs food every three to four hours, consuming about 600 ml of milk a day. By about 6 weeks this hunger cycle will have lengthened and the infant may pass a night without needing to be fed. 



         If human babies are not fed by their mothers, they may be bottle-fed with pasteurized cow’s milk, diluted and sweetened or mixing milk powder with water. These can be a valuable substitute for breast milk, but there are hazards involved. If not properly washed, the bottle may contain many bacteria which may cause harmful diseases to the baby.



          Some mothers believe that stronger milk helps the infant to sleep and grow better. But this is a faulty reasoning. A concentrated feed will contain too much sodium and the infant’s kidneys would have to work furiously to eliminate it. This may cause dehydrations. Although the infant may appear to be growing quickly yet instead of building stronger bones and more muscles, the baby would just accumulate excess fat, which is not a healthy sign.



         Babies have also been fed on milk of goat, buffalo, reindeer, caribou, sheep, camel, llama, and mare etc.



         During the second part of the first year, the infant is gradually weaned from milk to solid food. It is important that a balanced diet is maintained for a proper healthy growth of the baby.  


Where do penguins live?

               Penguins are a peculiar category of sea birds which can stand up straight and flat-footed like us. Do you know where these birds are found?

               Penguins are found in Southern hemisphere. They live along the Antarctic continent and islands as well as on the cool Southern hemisphere coast of Africa, Australia, New Zealand and South America.



              The wings of penguins have evolved into flippers. As a result, they can not fly but they are excellent swimmers. They walk in a strange manner. In the earlier phases of evolution they could fly like other birds. But over a period of time, their wings became very short. The reason is that penguins lived in the remote areas of Antarctica, where they had practically no enemies to attack them. So they lived safely in land and water without ever using their wings and in course of time their wings became very small. 





            



             



               Penguins live in flocks. A single rookery may contain more than a million penguins. They feed on fish, squids and crustaceans.



               Penguins withstand extremely cold conditions on account of a very dense plumage all over their bodies. These feathers are waterproof and have tiny air spaces that help them keep warm. Underneath this thick coat of feathers, there is an insulating layer of blubber. This helps to keep the body warm and store food and water. They also have a thick coat of fat to protect them from the cold.



               Female penguins lay one or two eggs, which are brooded by both parents. They do not take food during incubation. Young penguins are fed by regurgitation. There are 17 species of penguins. The species differ mainly in head pattern and in size. Their sizes vary from 40 cm (fairy penguin) to almost 120 cm (Emperor penguin). Both sexes are alike in size. Only two, the Emperor and Adelie penguins breed on the Antarctic coast. King, Macaroni, Chinstrap and Gentoo penguins breed on Sub-Antarctic islands. The remaining 11 species breed farther North.


How can dogs be dangerous to us?

          It has often been said that a dog is a man’s best friend. In fact, the dog was the first animal to be domesticated by man. But dogs can also be a source of danger under certain conditions.



         A dog can harm people by biting or transmitting several bacterial, viral, parasitic, fungal and rickettsial diseases.



          Bacterial diseases transmitted by dogs are mainly tuberculosis brucellosis, splenic fever, scarlet fever, diphtheria etc. Dogs carry Salmonella enteriditis and S. typhinurium pathogens which cause gastroenteritis and typhoid in man.



Dogs along with other animals can transmit fungal diseases such as ringworm.



          Rabies is the most dangerous viral disease caused by a dog-bite. Rabies virus is found in the saliva of rabid dogs. Sometimes even pet dogs can be the cause of this disease. Therefore it is essential that they should be vaccinated against rabies every three years.



          Dogs occasionally get measles and mumps and can cause this infection to spread to human beings.



        


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Which are the large-sized flying birds?

               The largest of all living birds is the African Ostrich which cannot fly at all. It measures upto 2.4 m in height and may weigh more than 133 kg. On account of its weight, it finds it impossible to lift its body in the air.



               The two groups of flying birds that have the largest wingspread are the albatross and the condors. Both of them weigh about 13.5 kg. 





 



 



          The wandering albatross leads among the largest flying birds with a wing-spread of 3.3 to 3.6 m. The albatross has a long, heavy beak and long, narrow wings. It is mainly found in places south of the equator. It is a sea bird. It needs some wind and a run before taking off. So it either runs along the ground or paddles with its webbed feet across the water for a long time before being able to fly.



 





 



               Next comes the condor which has a wingspread of 3 to 3.3 m. It is a carnivorous bird. There are two species of condors in the world. The Andean condor lives in the Andes Mountains in South America. The other one is the Californian condor which is found in the mountains of Southern California. They feed on carcasses of animals. While searching for food, the condor uses its broad wings to glide high in the air.



 



 



         



              The third bird in this line is the king vulture which is found in South America, Mexico and Central America. It has a wingspread of 2.7 to 3 m. The white pelican comes after the king vulture. It has a wingspread of 2.4 to 2.7 m. It is found in Canada. One of its distinguishing features is a bag-like pouch under its bill. Functioning like the radiator in a car, it helps the pelican to keep cool.



           



   The great bustard, a large goose-like bird related to the cranes comes next. It is found in parts of Europe, Asia and Africa and has a wingspread of 2.4 to 3.7 m. The American bald eagle is the next largest flying bird having a wingspread of 2.1 to 2.4 m. Then comes the sandhill crane, with a wingspread of 1.8 to 2.1 m.


Why do flies rub their legs together?

            Fly is a two-winged insect that has some 90,000 different species of it. The housefly (musca domestica) is one of tie most common of all flies. You must have seen flies rubbing their legs together. Do you know why they do so?



            The housefly has a dull gray, bristled body that is about 7 mm in length. It has large reddish compound eyes. Its mouth cannot bite but consists of a spongy pad. It has a peculiar system of feeding itself. At first it releases saliva and digestive juices over food and then sponges up the resulting solution. In this way, flies contaminate large amounts of food with germs, and cause millions of deaths every year. Hence it is widely considered as a major health hazard.



            The whole body of the housefly, including claws and padded feet, is covered with bristles. Even its tongue is coated with sticky glue. A fly rubs its legs together just to clean itself. In the process of rubbing the legs, it scraps some of the material that has gathered on the bristles and thus drops germs of dangerous diseases on the food. When we eat this food, we may get infected. Some of the most common diseases spread by the housefly are typhoid, tuberculosis and dysentery. Flies gather such germs from garbage and sewage.



            Houseflies usually live and breed in or near garbage or organic wastes. The female lays about 100 eggs at a time and as many as 1000 during her life. The eggs hatch into larvae in 12 to 30 hours. The larvae moult several times before becoming pupae. Within a few days, the pupae become adult and the cycle begins again. Most houseflies have a lifespan of about 30 days during summer and longer when the weather is cooler. Cold weather usually kills the adults; but larvae and pupae are able to survive the winter.





 

Which is the world’s deadliest animal?

          The world’s deadliest animal is the sea wasp. It is a kind of jellyfish known as chironex fleckeri. Its tentacles are loaded with hundreds of thousands of microscopic stinging cells which inject cobra-like venom with poisonous barbed threads into any unfortunate creature that happens to brush against them closely. This venom is highly toxic and kills anybody in a few minutes. Pain and burning sensation caused by its venom are insufferable.

          The sea wasp is a colourless creature and has a bell-shaped body which consists of 95% water. It is so elusive that only careful eyes can spot it drifting in shallow tropical waters of seashores and beaches. 





          The size of a sea wasp varies from 4 cm to 20 cm across and 10 cm long. It has purple or blue tentacles which can be seen coming out of the bell. These may reach up to a length of 120 cm. One wasp may have upto 50 tentacles and one such tentacle may have 750,000 individual stinging cells, capable of injecting venom. They are mainly meant for securing food, and also to serve as a defence mechanism.



          Chironex fleckeri is found in great numbers in waters of Northern Australia. They are also found in the United States, waters off the Atlantic coast from North Carolina to the south of Florida Keys. They have also been discovered in West Africa and Indian Ocean.



          Scientists have not yet been able to devise any effective remedy for its venom. So one must be very careful while swimming in tropical waters!



          There are also some very poisonous sea-snakes that live permanently in the sea and are fully adapted to an aquatic existence. They swim with a sculling action of the paddle-shaped tail. They feed on fishes after immobilizing them with potent, fast-acting venom. 


How do insects reproduce and develop?

         Scientists have studied more than 800,000 species of insects. Do you know how they reproduce and develop?



          Reproduction in insects is usually sexual, the male inserting sperm into the female’s body. The fertilized eggs are usually not tended by the insects, but they develop near or in a source of nourishment and protection. In some cases, fertilization is external. This means that the female lays the eggs and then the male fertilizes them. Some insects produce eggs which develop into adults without being fertilized. This is a type of asexual reproduction and is known as parthenogenesis.



          As an egg develops, it goes through several stages before becoming an adult. Some primitive insects develop directly from the eggs. Most of them, however, go through several stages of development called metamorphosis. In complete metamorphosis, there are four stages of development: egg, larva, pupa and adult. In incomplete metamorphosis there are three stages: egg, nymph, adult. The nymph is like a small adult. As the insect goes through its development, it moults several times. The entire process of metamorphosis may take a few days or several years depending on species and environmental conditions. Many insects lay eggs which can survive the winter or other unfavourable conditions.



        


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What are the different types of rhinoceros?


The name ‘rhinoceros’ has Greek origin. In Greek rhino means ‘nose’ and keros means ‘horned’. The animal has one or two curved horns on its long nose. The horns grow throughout its life. Rhinoceros belong to the ‘odd-toed’ group of ungulates. Rhinoceros are found in Africa and South-East Asia.



The animal carries its large body on its four stout, short legs. It has three toes on each foot, each toe ending in separate hoof. Each front foot actually has a fourth toe, too, that is no longer used.



The skin of the rhinoceros is very thick and has little hair. They look as if they are wearing heavy armour plating held together with rivets. The horns are composed entirely of hair like growths set above thickenings of the nasal bones and frontal bones. They are not attached to the skull and may even be torn off in fighting. When this happens, they quickly grow again. The horn may be upto 107 cm in length.



There are five different kinds of rhinoceros existing today — two from Africa and three from Asia. The Sumatran rhinoceros have two horns whereas the other two Asian species — Indian and Javan — have only one. They are all in danger of extinction but the most endangered is the Javan rhinoceros, which survives only in one small reserve.



The largest of all these is the white rhinoceros from Africa. It stands 1.8 m (6 ft) high at the shoulder and can weigh over 3 tons. An interesting difference between the white and the black rhinoceros lies in the shape of their lips. The white rhinoceros has a wider, square-mouth which is very suitable for cropping grass. The black rhinoceros is more of a browser and has a pointed upper lip for grazing and plucking leaves and shoots from shrubs and bushes. The other two-horned species, the Sumatran rhinoceros, is the smallest of all, standing only about 4.5 ft at the shoulder and weighing less than a ton. 





Rhinoceros feeds on grass, twigs and shrubs. They do not hunt other animals for food. During the afternoon heat, the rhinoceros usually buries itself in muddy water. And from here it emerges with a layer of mud on its skin. This dries and forms a protective coating against insect bites.



This huge animal is usually quiet and retiring. But if it is cornered, it can become very fierce and dangerous. A rhinoceros can charge at a speed of 30 miles an hour, and use its strong, pointed horns to attack its enemy. In captivity the rhinoceros may live upto fifty years.



A female bears only one young at a time. The calf is born about eighteen months after the mating season and remains with the mother for several years.



Now unfortunately the rhinoceros is a rare species. Over the centuries they have been hunted by man for their horns. This is because according to an ancient belief, its horn imparted magical properties to its owner. However, now this second largest land mammal is being protected by law to prevent it from becoming extinct.


Which is the most dangerous bird in the world?

          The cassowary is the most dangerous bird in the world. Its inner toe has a long dagger-like claw that acts as a weapon and can slash open a man’s stomach!



          The cassowary is found in New Guinea and Northern Australia. It is a secretive forest dweller and is seldom seen, but often heard croaking and bellowing. It cannot fly, but runs at a great speed on its powerful legs. On each foot it has three toes, the inner one having a long straight claw. It can often be seen giving furious kicks at the trunk of trees without any apparent reason. Because of this strange habit the cassowary is regarded as having a very bad temper. In dense forests it can even speed upto 50 km an hour. It can grow upto a height of 6 ft and weigh as much as 180 pounds. When it gets annoyed, it jumps in the air and delivers a vicious kick.



          It is a bony-headed bird. Its naked blue head is protected by a bony helmet. Its body is covered with coarse hair-like feathers. It is the only member of the family casuariidae. Unlike other birds, the male incubates eggs. At a time three to six eggs are laid. The eggs are green in colour and 13 centimetres long. They are incubated for 50 days in a leafy nest and on the ground. The adult provides parental care for the young ones.



          Cassowaries live in family groups or in pairs. They like to be near water, for they swim readily. They are also good fishers.



          According to zoologists, the cassowary’s ancestors were able to fly. But in the process of evolution, it became flightless. It has adapted itself to make the most efficient use of its environment. Emu, kiwi weka and takahe are also flightless birds. Most of the flightless birds are found in Australia and New Zealand. 




Why do woodpeckers peck the trees?

          



    A woodpecker is a bird which gets its name as it pecks the wood of trees, looking for insects to eat. The woodpecker is a great help to the trees because quite often, the insects and worms are harmful for the trees. These grubs and insects remain hidden deep in the crevices of the bark of trees. The woodpecker can find them instinctively even when they cannot be seen outside. Then he drills a deep hole and straight gets down to them. Sometimes woodpeckers make two openings, like a front and back door. This is to enable them to get away if an enemy shows up.



           The woodpecker has a chisel-like beak which can drill holes into dead or unhealthy trees. The structure of the head and neck of a woodpecker is adapted for driving its beak powerfully forward into the tree bark and absorbing the shock of the blow. It then uses its long tongue to capture and eat worms and insects. They can bore holes in the trees. Most woodpeckers nest in large holes that they dig in the branches or tree trunks. 



 





             



 



 A woodpecker is a member of the family picidae. There are 24 species of wood-peckers found in North America. These include the flickers and sapsuckers. The downy woodpecker can grow upto a length of 14 cm. The pileated woodpecker, found in the Eastern and North-Western United States and in parts of Canada, often reaches a length of 34 cm. The pileated woodpecker chisels large, deep, oblong holes into tree trunks.



               The European green woodpecker is green with red crown and yellow rump. The greater and lesser spotted woodpeckers are the British species. They have black, red and white plumage. There are about 210 species of woodpeckers worldwide except in Australia.



 



 


Which insects have the longest lifespan?

               Most insects live only for a short span of time compared to other living creatures on earth. Do you know which insects have the longest lifespan? 





The longest living insects are the Splendour Beetles (Buprestidae), some of which remain in the larva stage for more than 30 years. They pass through a complete metamorphosis. In the young larval forms they are very varied and include some of the largest and smallest of all insects. The largest is ‘Hercules Beetle’ of South Africa which is 15 cm long. The smallest is only 0.05 cm. Queen Termites (lsoptera) previously thought to live 50 years or more, are now known to have a maximum lifespan of 15 years.



Apart from these two insects, there is one insect called cicada that actually lives for 17 years. Its lifecycle is very interesting. The female cicada lays eggs on the twigs of trees. When the young one (nymph) hatches, it drops down to the ground. Then it burrows itself into the ground and attaches itself to the roots of plants and trees. Here it remains motionless for about 17 years, sucking at the sap of the roots. After this long burial, it is driven by some mysterious instinct towards light. It climbs the tree trunks and its skin splits open and the mature cicada emerges.



For about five weeks, it leads an active life in the sunlight. After this it just dies. So it takes 17 years to develop for just five weeks of active life.



The male cicada makes a shrill sound which can be heard in the countryside. It is well known for the monotonous, whining songs of males. This sound is probably a mating call. According to scientists, the noise-producing organ of the cicada is probably the most complicated musical organ to be found in nature. The male cicacta has little drum-like plates which constantly vibrate by muscles that never seem to get tired.



There are more than 800 species of cicada and 100 of these are found in North America. But the 17-year cicada is found only in the United States. Most of the other species live only for two years.


Why does a peacock display its feathers?

          A peacock displaying its feathers provides one of the most spectacular sights. Do you know the reason behind it? 





          Peacock has a beautiful train of feathers which he displays during the breeding season. It usually attracts several females by such display, but as soon as any of them approaches, it turns its back. The reason for this peculiar behaviour is not clear. But it is certain that this is done to woo the female. In Greek mythology the pattern of the peacock’s tail feathers represents the eyes of Argus – a giant with 100 eyes.



          Peacock is the national bird of India. It belongs to the family phasianidae. Strictly speaking, the male is a peacock and the female is a peahen. Both are together known as peafowl. There are two species of peafowl. One is found in India and Sri Lanka and is blue in colour. The other species is found in South-East Asia which is green in colour. In fact, peacock is a native of Asia and the East Indies, from where it has been brought to other parts of the world.



          The male of both species has a 75 cm long body and 150 cm long tail. The female is smaller than the male. The tail is made up of beautiful feathers. In display, the peacock lifts its tail, brings it forward, enveloping his body as he struts and quivers, audibly rattling the quills and uttering loud screams. Generally, a peacock has a train of upto 150 tail feathers, which are erected by it in display to form a showy fan.



          The blue peacock’s body is metallic blue green. The green peacock has a green and bronze body. The hens of both species are green and brown. They do not have the train of feathers or ‘crown’ on them.



          In the wild, they live in open lowland forests, flocking by day and roosting high in trees. The male usually has a harem of one to five hens each of which lays four to eight buffy or white eggs. Peafowls are omnivorous, i.e. they eat both plants and animals. They can eat young snakes.



 


Why do insects get attracted towards light?

          You must have seen insects buzzing around a glowing lamp or bulb in your homes. The surprising aspect is that it is only the male insects that get attracted towards light. Moreover, insects are not attracted equally to all sources of light. Do you know why this happens? 



          The attraction of insects to light has been a subject of interest to researchers since Aristotle’s time. In the late nineteenth century, this phenomenon was studied in great detail by S.W. Frost of Pennsylvania University, U.S.A. Later, from an extensive study of this subject, a French entomologist, J.H. Fabre was able to provide a proper explanation.



          Fabre put forth the theory that certain radiations coming out from the light source are responsible for the attraction of insects. This has now been confirmed by some experiments that a series of narrow bands of infrared radiations emitted by the source of light, produce the attraction for insects. This study was conducted on moths.



          There is a gland at the tip of the female’s abdomen from which it releases some acetate molecules. These are called pheromone or sex scent. This chemical emits some infrared radiations which spread through air. The male moth, flying at some distance from the female, picks up these radiations and gets attracted towards the female.



          The most acute sense of smell exhibited in nature is that of the male emperor moth (Eudia pavonia) which according to German experiments in 1961, can detect the sex attachment of the female at a distance of almost 11 km. Some moths get attracted towards light under the impression that some female moths are there. Thus the search for the female leads it to the light.



          Candle lights emit sufficient amount of such radiations, thus attracting a lot of male insects. Insects are also attracted to street lights for the same reason.



          It has been found from different studies that the pheromones of different insects are not alike. That is why all insects are not equally attracted towards light. Similar is the case with different light sources. If a light source does not produce these infra-red radiations, insects will not be attracted towards it. This process of insect communication is very complicated and needs sophisticated equipment for study.


Do insects have organs and blood?

          Insect is such a tiny creature that it is difficult to believe that it has a circulatory system and has blood in its body. But interestingly insects have a heart, blood and other organs.

          Insects are found everywhere in the world, except in the deep seas. Fossils indicate that they have existed on earth for more than 400 million years. They have been able to adapt quickly and efficiently, to environmental and climatic changes.



          The body of an insect is divided into three sections: head, thorax and abdomen. The head has one pair of antennae which serve to convey the senses of touch, taste and smell. There are usually two compound eyes which provide proper vision and two or three simple eyes (ocelli) which detect light or darkness. The mouth may have biting or chewing jaws or piercing and sucking structures. The head also contains a brain which connects with nerve cords in all parts of the body.



          The thorax or middle part of the body has three pairs of jointed legs. These legs are equipped with sticky pads or claws at the end. Insects are the only invertebrates with wings. Although most insects have two pairs of wings, some have only one pair or no wings at all.



 


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How do aquatic animals survive in frozen lakes?

            In cold countries, when the temperature falls below the freezing point, water, lakes and rivers get frozen. Under such conditions, how do aquatic plants and animals survive?

            Generally all liquids expand on heating, but water is an exception. At 0°C, if water is heated gradually, its volume decreases and this contraction continues till the temperature rises to 4°C. Above 4°C water starts expanding and keeps on expanding with further rise in temperature. This shows that at 4°C, the volume occupied by a given mass of water is minimum. In other words, the density of water at 4°C is maximum. This irregular expansion of water is known as anomalous expansion.



            This anomalous expansion of water plays an important role in nature. Due to this only the upper layers of water in the ponds and lakes in cold countries get freezed. Lower layers remain as water, and as a result aquatic animals survive.



            In cold countries, during winter when the atmospheric temperature is very low, the upper layers of water in the lakes and ponds start cooling. When the temperature of the surface layer falls to 4°C, the water acquires maximum density and sinks down. The lower layers of water then rise up. This water also gets cooled to 4°C and again sinks down. The process continues till the temperature of the whole water falls to 4°C. As the temperature falls below 4°C, the density of water decreases and as a result water at the surface becomes lighter and does not sink down. The surface water finally freezes while the lower layers remain at 4°C. As ice is a bad conductor of heat, freezing in the lower layers is a very slow process. Thus underneath the frozen layer, fish and other aquatic animals and plants survive. Had the expansion of water been uniform, the lakes or ponds would have been completely frozen, along with the aquatic plants and animals. In this situation no plant and animal would have survived.