My Science School

               Adaptation is a biological term which means the process by which all living things change or adapt to new and unfavourable conditions for their survival. Thus human beings, plants and all other living things adapt to their environment for survival. 

               In plants, take the example of the oak tree. Since it grows in a moist climate, its green leaves require much water to carry on the process of photosynthesis. On the other hand, since the desert cactus cannot afford large leaves that would lose more water, its leaves are reduced to spines that grow out of a waterproof stem. To come to some animals, the beaks of birds are again adapted to particular ways of feeding. For example, preying birds like woodpeckers and kingfishers have sharp strong beaks to tear their prey.

               There are two kinds of adaptations: individual adaptation and group adaptation. In individual adaptation an individual adapts himself to new conditions automatically in his lifetime. Group adaptation refers to adaptation by a group. It is a slow process and occurs over many generations. For instance if a man’s job is such that he has to work during night time he would have to adapt to such a routine gradually. To begin with, he may have some difficulty in sleeping during the day but when adapted to the changing requirements after sometime, he would sleep easily. 

Continue reading "How do living beings adapt to their environment? "

               There are about 2000 lizard species in the world including chameleon, iguana and skinks. Skinks are one of the two largest families of lizards. They are found in all the tropical countries but they are most abundant in Africa, East Indies and Australia. They belong to the Cincidae family. There are about 700 species of skinks. Skinks are shy and retiring, so people are mostly ignorant of them.

               Skinks have very thin, small legs. They have a smooth skin and a small pointed head. They can crawl over the uneven surface. Unlike snakes, thin jaw bones are fixed. Most of them are ground dwellers.

               A very strange characteristic of skinks is that they can see with their eyes closed. While burrowing or eating insects they close their eyes. They have a permanent, transparent eye lid cover over their eyes with which they close their eyes. As this lid is transparent, skinks can see with their eyes closed.

               Another characteristic feature of skinks is that they can squeeze their size during the squirming movement through the soil. In some skinks the feet look ridiculously small when compared to their body size and in others they get disappeared altogether.

               Some skinks lay eggs, others bear live young. These skinks include the tiny three-toed skinks of southern Europe and north Western Africa. They grow upto 40 cm long of which half is tail. Australian skink stores fat in its tail and looks the same from both ends. It feeds on fruits, insects as well as small animals.

               Now the question arises why skinks close their eyes? When skinks move in the dust, the dust can enter its eyes. So to protect against dust and sand it closes its eyes.

 

               Albatross is the largest flying sea-bird. It can have a wingspan of 3.15 m (10 ft 4 in.) at full stretch. It belongs to Diomedeidae family and is found mainly in south of the equator. It has a long, heavy beak and long narrow wings which allow it to soar on the wind seemingly without effort for hours. Its body is about 1.2 metres long.

               There are more than a dozen species of Albatross. It experiences certain difficulty in taking off. It needs some wind and must run along the ground or paddle with its feet across the water for a long time before it can soar.

                Like other oceanic birds, albatross also drinks sea water. Although it normally lives on squid, it is attracted to ship’s garbage. It comes ashore only to breed in colonies on islands. It lays a single large white egg on ground in the open, which is incubated alternatively by the male and female parent. The growth of a young albatross is very slow. It attains flight plumage in 3 to 10 months, and then spends the next 5 to 10 years at sea, learning navigation and feeding techniques. Albatrosses live long and are among the few birds that die of old age.

               However, among the sea birds which use wings for swimming and not for flying, the largest is the Emperor Penguin of Antarctica. Standing over one metre high and weighing 40 kg, the Plum Emperor lives in the most remote shores of the great ice-bound continent.

               The largest ever recorded specimen of albatross was a very old male with a wingspan of 3.63 m. (11 ft. 11 inch). This was caught by the members of the Antarctic research ship in the Tasman Sea on 18 September, 1965.

               It is established by the scientists that the most successful free living kinds of animals judged by the number of species and standing stocks of living substance, have come from marine surroundings.

               In 1964, Sir Vernon Wigglesword had suggested that, at first these animals might have lived along the shore lines and later moved in two directions. A part colonized the open sea and ocean deeps to give rise to crabs, crustacea etc and the other part moved to land areas.

               Crabs are mainly marine animals - although some live in fresh water or land. They are ten-legged alert carnivores that act as scavengers. There are many species of crabs worldwide; such as European crabs, shore crabs, edible crabs, fiddler crabs, river crabs, common hermit crabs and robber crabs.

               Among all these, robber crabs or commonly known as ‘coconut crabs’ are well adapted for living on land, although their larvae first live in the sea. But if an adult robber crab is left under water beyond 24 hours, it will be drowned ultimately. These are the crabs which can climb trees.

               The robber crab (Birgus Latro) is an extremely large land crab of South-West Pacific and Indian Ocean. Adults of robber crabs are about one metre long (40 inches) and weigh about 15-17 kilograms. A robber crab uses two large chelae or pincers to pound or chip coconuts to eat the soft white portion of the coconut. They climb coconut trees to detach coconuts from tree tops through they are quite unable to get inside a coconut on their own. They apparently eat coconut meat already broken into the ground by other means.

               The colour of a grown crab ranges from light violet to brown and deep purple with black strips on their legs. The female lays her eggs in sea. In larval state, it lives in water, feeding on small organisms. After about a month when it is grown to intermediate stage, it leaves water to live in a shell for 3-4 weeks. It then discards the shell and buries itself in moist sands, and transforms into an adult robber crab. Its meat is a local delicacy. 

               A dog, like a cow, an elephant, or a man, is a mammal. All mammals are warm blooded, or homothermic animals. In the animal world only mammals and birds are warm-blooded creatures. The rest of the animals are cold-blooded or ectothermic. A warm-blooded animal has a relatively constant body temperature, while the temperature of cold-blooded animals changes according to surroundings. 

               Heat is being constantly produced in our body. A part of it escapes through our skin. We have sweat glands under our skin and sweat comes out through small pores in it. When sweat evaporates, it absorbs heat from the body producing a cooling effect.

               Unfortunately, not all mammals can use this method to get rid of their body heat.

               For example, a dog has few sweat glands and, therefore, cannot sweat like us. Similarly, tigers, lions, cheetahs, etc. cannot sweat much. Birds and rats also cannot sweat.

               A dog has a different mechanism to control its body temperature. It does so by hanging its tongue out. When a dog pants, it takes in air through the nose and gives out air through the mouth. The saliva in its mouth evaporates. Evaporation of saliva produces a cooling effect and the dog feels comfortable. This habit of panting is simply a natural urge of a dog to control its body temperature in accordance with its surroundings.

               An elephant also maintains its body temperature in a very interesting manner. Its skin is very thick and not much heat can escape through it. However, the skin on its ears is much thinner. The elephant, therefore, tries to get rid of the body heat through its ears. Nature has given the elephant very large ears which it can flap in a bid to lose heat. The skin of our ears being quite thin, the ears feel cold on a winter day.

 

               Many animals and creatures rest during the day but become active at night. Similarly there are many plants which bloom at night only. Such plants are called night blooming plants. The flowers of Raat Ki Rani (Queen of the Night) also fall in the same category. Many night flowering plants belong to the honeysuckle and nightshade families. Do you know why do flowers of Queen of the Night bloom at night only? It is quite often in the case of night flowering plants that they resort to the use of scent, thereby attracting high-flying insects and moths.

               When these insects sit on the flower, a few pollen grains get stuck to their tiny feet and wings. When the same insects go to other flowers of the same variety, the pollen grains are deposited on the flower. This process helps pollination, without which a flower cannot mature into a fruit. Thus we can say that flowers of the Queen of the Night bloom at night to attract those insects which help the process of pollination. Flowers produce fruits and fruits produce seeds. The seeds are responsible for producing new plants.

               Most of the flowers blooming at night are those which cannot bear high temperature and light of the day time. Flowers of Raat Ki Rani also avoid extremes of temperature and daylight by blooming at night.

               There is one more fact about the night blooming flowers. Such flowers do not have attractive and pleasing colours as these colours are not visible in the darkness of night. Most of the night blooming flowers are white because this colour is easily visible in the darkness of night and quite effective in attracting the insects for pollination. In fact, all white or cream coloured flowers such as night-scented stock are pollinated by night-flying moths which are attracted by strong perfumes of the flowers.

               Thus we see that flowers of Raat Ki Rani are not capable of withstanding day temperature, usually white in colour and have a delicious fragrance with which they attract insects. 

               Tuatara or Sphenodon punctatus is a strange lizard like animal that has three eyes. It is the only animal in the reptile group which is placed in a separate sub-group rhynchocephalia. Although it resembles lizards, it is truly a precious living fossil, since this reptile order goes back to the time of the dinosaurs. Tuatara is found only on the islets of New Zealand. A full grown male weighs upto 1 kg but females weigh only half that of a mature male of similar age.

               The strange thing about this animal is that it has three eyes. The cone like third eye is called the pineal eye. This eye is situated in a hole between the head and brain. It has an eyelid over the third eye which closes horizontally. One can’t say anything about the use of the third eye of this animal but certainly it had some use for these prehistoric animals.

               This animal is active at night. Generally it lives in burrows often in company with sea birds. It is a very shy and retiring animal. It eats insects, other animals like frogs, rats and eggs of birds also.

               The average life of a Tuatara usually does not exceed 77 years, but some Tuataras may live upto 100 years. Male Tuataras are unusual in the sense that they have no copulatory organ; their matings are accomplished by cloacal apposition. Female Tuatara lays 8 to 15 eggs in the spring, at some distance from its burrow. Hatching of eggs occurs in the next summer which means that hatching takes about one year of time.

               It is a unique animal and represents a whole vanished order of reptiles. All other species except this one became extinct and only this particular type has lived unchanged till the present day. In captivity it can live upto fifty years only.

               This strange animal is now facing extinction. The government of New Zealand has been making great efforts to prevent the extinction of this animal.

 

               Cocoa originated in Central and South America. It is said that Christopher Columbus introduced cocoa beans in Europe in 1502. The cocoa seeds however were first commercially planted in 1879 in Ghana. Upto 1913 Ghana was the leading cocoa producing country in the world. Even today Ghana is the largest cocoa producer. It is believed that several lakhs of people are associated with the production of cocoa in Ghana.

               The cocoa trees grow to a height of about 7 metre. It is an evergreen plant. Twice a year, small, star like, pink and yellow flowers appear on it. After sometime flowers grow into fruits or pods of the shape of an egg which are about 6-10 inches long and 3-4 inches thick. These pods take about six months to ripe.

               Equatorial regions are most suitable for growing cocoa trees. It needs constant moisture and in some countries watering is also necessary. Regions having a rain fall of 50-100 mm are most suitable for these plants.

               Generally there are two crops of cocoa —first crop from October to March and other crop from May to August. When cocoa tree is five years old it starts bearing fruits. The ripe fruits are cut with sharp knives from branches. Women and girls usually collect these in baskets and take it to another place where cocoa beans are scooped out from these pods. After this, beans are subjected to fermentation. For this purpose, beans are put into perforated boxes and heated at constant temperature. By this process which takes about six days, impurities are removed to bring out the flavour.

               Cocoa is used in many eatables. But it is mainly used in preparing chocolates. Chocolate powder is made from dry cocoa seeds. Cocoa butter is made by extracting fats from cocoa beans. In ice cream it is used for flavour. It is also used in the manufacture of some medicines. 

               In the world of nature we see a great variety of flowers. We have virtually flowers of every conceivable colour. Some are so perfectly symmetrical with vibrant colours that their beauty attracts us immediately. Some others are shaped like insects or lizards.

               Most flowers have fragrance. However, flowers are not just decorative creations but play a great productive role also. They produce fruits by the process of pollination and the fruits in turn produce seeds.

               In this great world of flowers do you know which the biggest flower is and which is the smallest? 

           

 

                The biggest flower in the world is Rafflesia arnoldii. It is found in the Sumatran Jungle and can have a diameter of over a yard. It is about 0.75 inch thick and weighs about 7 kg. The flower can grow to 91 cm. (3 ft) wide. It blooms for five to seven days. It is reddish or orange brown in colour. It has an unpleasant odour which is attractive to flies. These flies carry out the pollination process. Rafflesia is a parasitic plant and feeds on the sap of trees. It does not have any leaves. 

 

 

 

 

 

 

 

 

                The largest recorded chrysanthemum flower was cultivated by Francois Santini of Indre - et - lorie, France. This giant flower was 2.5 m (8ft. 2 inch) tall and had 4041 blooms. 

 

 

 

 

 

 

 

Continue reading "Which are the largest and smallest flowers? "

               There are about 5000 species of reptiles. These include lizards, tortoises, crocodiles, etc. Most of the species of reptiles live on and but there are some which live in water. Their length varies from 5 cm to 10 metres. The smallest lizard is found in tropical regions while python is the largest snake. All reptiles are cold-blooded animals. Although they are found everywhere on earth but they are most common in tropical regions. Do you know among all reptiles which are the most beautiful?

               The European Green Lizard is the most beautiful reptile. It is the second largest lizard to be found in Europe — the male reaching a length of 16 inches, its tail alone being 10 inches long. 

               Green lizards are found throughout Europe although they do not have natural habitats in Great Britain. Attempts have been made to establish colonies but it is believed that the climate there is not really warm enough for their survival. They are most commonly seen in Mediterranean countries, basking on the rocks and among the ruins. There is also another kind of lizard known as Arizona Lizard. It has a bright black and white colour in its body.

               Green lizards are sold in petshops. Their elegant reptile shape and attractive colouring attracts people to buy them. It is not difficult to keep them as pets. They only need proper care. They feed on insects, spiders and worms.

               Most lizards are harmless. The only lizards with a poisonous bite are the Gila Monsters with black and white marks on their body.

 

               All of us have seen snake charmers playing their pipes before a snake. When a snake charmer plays his pipe, swinging it backwards and forwards or jerking up and down, the cobra raises its head and moves in rhythm with the music. There are many folklore about snake’s love of music. Some snake charmers even claim that they can summon snakes by playing on the pipe. Do snakes really love music?

               The snakes do not have an auditory structure. They have a bony rod called columella auris. This bone extends from the fenestra oxalis to the quadrate bone. This bone has a special structure which helps it to detect the ground vibrations. But it cannot detect vibrations in the air. Due to this a snake detects an approaching ball.

               In order to verify whether snakes can detect the vibrations produced in the air or on the ground, a number of experiments have been conducted with different species of snakes by P.J. Deoras at the Haffkins Institute, Bombay. He put a snake inside a tin box and studied the effect of soft music near the tin box. He found that any sound that caused the tin to vibrate made the cobra to raise its head. He took a snake charmer inside his snake farm and found no response for air borne music. However, it responded to ground music.

               Experiments on five other species were also conducted. And again the findings were that the snakes did not respond air-borne music. However, they responded to the music of drum which creates vibrations in the box or earth.

               In short, it can be said that snakes are very sensitive to sounds that create vibration on the ground. Because of this fact, the snake charmer hits his pipe with the ground to make the vibrations reach the snake. A snake charmer also hits the snake with the pipe and tries to excite him. Actually it moves its body only to keep an eye on the moving pipe.

 

               On the basis of autumn defoliation (shedding of leaves) trees and plants can be divided into two groups. The first includes those plants and trees which undergo defoliation every year and are called deciduous trees, while the other includes the evergreen plants or trees which defoliate very slowly and remain green throughout the year. Evergreen plants also undergo defoliation but at one time only a small portion of their leaves fall off.

               Every year with the approach of autumn the trees begin to have their period of rest. In autumn the leaves fall and eventually rot down to give the leaf-mould and humus, which are essential to support rich vegetation. During this period gradually their leaves turn yellow and then curl up and fall on the ground. The tree then remains almost completely inactive until the arrival of spring. The denuded or defoliated trees or plants are a sad sight but at the same time very useful to plants because after it plants get a new life and look. Before defoliation the leaves take yellowish, brownish and reddish hues.

               But why do the trees shed leaves? We know that plants are living organisms which need food to survive. This food is obtained by utilizing the organic substances provided by the leaves. Just like animals, plants also produce waste materials and have to get rid of them, but they do it in a different way. They have to retain waste materials in their tissues until autumn. When the time comes for trees to shed their leaves, the plants extract all the useful products from them, and shake off the waste materials behind. Due to the presence of these waste materials the leaves turn yellow, brown and red. When the leaves are shed a layer of dry needles is left on the tree and it is visible in winter.

               Autumn is thus the period in which the trees get rid of their waste materials.

 

            All vertebrates except man have a tail. According to scientists, there was a time when man also had a tail. But when he stopped using it, it fell into disuse and became extinct. We still have a mark of a tail on our body. Do you know what the usefulness of a tail in different animals is?

            The tail is found in the post-anal part of the body. It has different uses in different animals. In fishes it is surrounded by a tail fin and plays an important part in providing forward thrust. They have different types of tails. These help them in swimming and providing the upward movement.

            In crocodiles and whales the tail acts as a powerful organ for locomotion. In frogs and toads the tail and tail-fin are present only in the larval states and absent in the adult. Crocodiles use their tails for defence and also to attack their enemies. 

               All reptiles possess a well-developed tail. The length of these tails is different in different reptiles. Tortoises and turtles have short tails while lizards have long ones. If somebody attacks a lizard, it can break a part of its tail. It is a defence mechanism. Reptiles perform wriggling movements with the help of their tails. Lizards after sometime regenerate a new tail. In chameleon the tail is quite long. It can be rolled downwards to coil round the branches for extra grip. The tail of snake is small in size. It acts as a storehouse of fat. The tail of the sea snake is small in size and oar-shaped, and helps it in swimming.

               Real tail in birds is extremely short and stumpy. It gives a support for the feathers. Feathers help birds in flying.

               Most mammals have well developed tails. With these they can get rid of flies. Men and apes do not have such tails. Whales have two lobes of tail fin of which one is at right and one, at left. It helps it in swimming. The tails of kangaroos and squirrels act as a balancing organ during walk and leap. During winter season when squirrels hibernate, the hairy tail acts as a blanket. Rabbits use their tails for providing warning signals. Peacocks display their tails to attract the opposite sex. In this way we see that different vertebrates make use of their tails for some purpose or the other.

 

               The appendix is a part of the intestine in the human beings. Its full name is the vermiform appendix. The word vermiform means worm-shaped. The appendix is found on the lower right side of the abdomen. It is found at a place where our small intestine joins the large intestine. This is called caecum. It is in the form of a tube whose one end is closed and the other opens into the caecum.

               In human beings the appendix is usually three to four inches or eight to ten cm. long and less than half an inch wide. It was probably a necessary part of the digestive system thousands of years ago and perhaps helped in cellulose digestion. The organ is believed to be gradually disappearing in human beings and is often referred to as a vestigial organ — those organs or parts now disappearing for being in disuse but ancestrally well developed.

               The appendix has muscular valves, ordinarily capable of expelling the mucus secretions of the appendiceal valves into the caecum. If anything blocks the opening, the continued secretion and the bacteria within the organ build up pressure. It may also be invaded by germs. This causes the whole area to become sore and swollen. The painful inflammation of the appendix is medically termed as appendicitis. A person experiencing an attack of appendicitis may feel abdominal pain in the right lower region of the abdomen. He may feel nausea or have diarrhoea. There can also be slight fever unless the appendix bursts. Recurrent mild attacks of appendicities in children are often diagnosed as ‘bilious attack or disorder of biles’. The only safe plan is to watch such cases very carefully and immediate attention should be given for proper treatments.

               In acute cases, surgical operation is needed. It is operated on after giving general anaesthesia. The appendicitis is caused usually when bits of undigested food stick in the opening to the appendix and block it. This gives bacteria a warm, closed place where they can grow and multiply and produce a painful swelling. 

               We are all familiar with the itching sensation and scratching gives us some relief. But what causes it and why scratching gives a soothing sensation?

               When the pain nerves in our skin are stimulated a little, we do not feel pain but feel a tickling sensation in our skin, which causes a desire to scratch. A mosquito bite irritates the pain nerves of our skin just enough to cause an itch. Dryness of the skin or wounds on the body surface and various allergies can also cause itching. Similarly many other diseases like kidney disorders and cancer can cause itching.

               The best way to deal with mosquito —bite itch is to scratch lightly in a circle all around, but not directly on the place of bite.

               Scratching the skin at one spot may help for a while but can produce an itch at some other places of the body. According to some doctors, the reason behind it is that the pain nerves in the area around an itch become more sensitive. Scratching stimulates these nerves just enough to start a new itch. So the feeling spreads.

               Now the question arises, why is the skin the only part of our body that can feel an itch? This is a big mystery. We have pain nerves inside our body also but we never feel an itch in the inner organs such as liver or heart. The medical scientists are still quite ignorant about the reasons.