Friday, July 27, 2012

How did the First Bird Evolve?

            All species evolve form pre-existing ones. It is strange but true that the first species of birds originally evolved form reptiles about 140 million years ago. The evolution of birds followed the same course as that of any other species in a slow and gradual process. The originated from reptiles to develop to its present form passing through different stages. The first bird was called archaeopteryx and was of the size of a crow. Fossil records support the existence of this bird. But what are the distinct features that classified it as a bird?

Fossil Of Archaeopteryx

            Though, in appearance, it was quite like a reptile and had teeth like a lizard and a long bony tail, ye in many other ways it had different characteristics from that of reptiles. Its head was balanced upon a long thin and probably flexible neck. It had feathers made it a bird and not a reptile and that is why archaeopteryx came to be know as the first bird on earth.

            But it had several different features from the modern day bird. It could not fly properly for ay considerable distance as it was not able to flap its wings very hard and probably used them for gliding as well as sailing through the air. Ti had a small poorly developed breastbone. It had claws on its wings and was a warm-blooded creature.

            There is no unanimity among the ornithologists over the issue of the origin and development of such intermediate form of creatures. The following are the two different views given by two different schools.

            One group believes that the first creatures that could fly were the tree-dwelling reptiles that jumped from branch of branch or from trees to ground in order to escape form enemies or in pursuit of food. The wings developed as a mechanism to aid in gliding or to help ease the fall as we see in the modern flying squirrels.

            The other group says that the ancestral reptiles were in ground dwelling form, lightly built and protected themselves by speeding away from the enemies. The development of feather arms and tail aided in lessening the forward resistance of wind and provided the lift in the initial stages, which together increased the speed of the bird. These processes gradually enabled them to fly with more perfection.

Do some Plants Eat Insects?

            Insect eating plants have always fascinated botanists. These plants cannot prepare their own protein; therefore they obtain it by eating insects and worms. These plants are called insectivorous plants. Every plant of this kind has its own unique technique of capturing insects. The leaves of these specialized plants are adapted to trap and digest insects- which supplement their food supply.

Pitcher Plant 

            One of the most well-known insectivorous plants is the pitcher plant. The upper part of its leaf resembles a small pitcher. The color of this plant is very attractive and it contains a sticky liquid. The opening of the pitcher has small fibers, which allow the insect to go inside but obstruct its coming out. On being attracted by the beautiful color, when some insect enters this pitcher, it is unable to come out. It gets entangled produces certain enzymes and digests it. The cobra plant of America, which appears like a snake, also eats insects. It also has a pitcher shaped mouth.

            Another part, which feeds on insects, is the sundew plant. The sundew plants have hair on their leaves. The tips of these hairs have droplets of a liquid, which appear very attractive. As soon as some insect is attracted towards the leaf, the hair bends with the help of their own juice. The digested flesh is absorbed through their leaves. After that, the hair returns to normal.

            There is a plant called Venus fly trap which is found in America. Its leaves have beautiful red colored elevations o both sides. Whenever an insect sits on a leaf, it closes like a fork and the plat digests the trapped insect by digestive juices. The uticularia is a water plant. It is found all over the world. The roots of this plant that are submerged in water have bulbous bladders. When some aquatic insect enters the bladder, the hair on its opening does not allow it to come out. The walls of these bladders give out a digestive juice, which suck the proteins out of the bodies of the insect.

            Similarly, a plant called Indian pipe is found in the hills of shimla. It also eats insects. In addition to these, there are many other insectivorous plants all over the world.

Why do Giraffes have a Long Neck?

            Giraffe is the tallest land animal in the world, but one mystery, which baffles scientist, is how it got its long neck. A famous French zoologist jean Baptist de Lamarck proposed a theory that at one time giraffe’s neck was much shorter than what it is now. It had to raise its neck to eat the leaves of the trees. According to Lamarck, the part of the body, which is used most, develops most. The giraffe had to raise its neck time and again to reach the upper branches of trees when the leaves on lower branches of trees when the leaves on lower branches were eaten away. The excessive use of the neck resulted in its gradual increase. The successive generations of the giraffe started having longer necks and finally today’s long-necked giraffe emerged. The male giraffes grow up to height of 5.5 meters and weigh more than 1,000 kilograms. It is herbivore ad chews its food I spare time. The formation of giraffe’s body is such that its mouth can easily reach the leaves of high trees. Its tongue is about 45 centimeters long and constructed in such a way that it can eat even the leaves of thorny plants. It has a long upper lip that helps it wrench off many leaves at a time.

Giraffe

            The color of giraffes resembles the shadow of the trees and as such it cannot be easily spotted by its enemies. It is usually yellowish-brown in color and has highly sensitive ears.

            The giraffe’s ears can pick the faintest sounds, but it is nearly incapable of uttering sounds. The word nearly has been used because some of the female giraffes and their young do have been found mooing like cow or ox in the zoological parks but most of them do not utter sound. The reason for this inability lies in the underdevelopment of its voice box or larynx. Probably due to this reason, it has a keen sense of smell and sight. If attacked, it can run at a speed of 45 kilometers per hour for an extended period of time without getting tired. As far as fast running is concerned, it can bet even the fastest of horses. When some other animal attacks it, it retaliates with the help f its head and hind legs. As its eyes are far above the ground, it can easily see predators long before they can get close enough to attack. That is why even the lion has to be very cautious while attacking a giraffe. Lions always attack it form behind because giraffes strike with its head like a hammer.

What is Flying Fish?

             We must have heard of flying fishes. Have we ever wondered how it is possible for a fish to fly? There is a kind of fish, which can soar like a glider. This fish is known as a flying fish. It does not fly like birds because it has no wings. To fly, it first swims very fast on the surface of water up to a speed of about 65 kilometers per hour and then spreads its front fins and starts flying in the air. The fins remain spread firmly during the flight with help of its muscles. But as soon as it lands on water. The fins return to their original position.

Flying Fish

            The most common flying fish is the two winged type, which is found in all tropical seas. It is about 25 centimeters long. The largest flying fish is bout 45 centimeters long and had four wings. It lives off the coast of California. The length of flying fishes varies from 5 centimeters to 45 centimeters. Sometimes while flying it dashes against the water waves. This sight is one of the most breathtaking sights that tone can experience. The collision with waves gives it extra energy and it can further fly up to greater distances. It usually flies quite high in the air. A flying fish can glide for over half-a-minute.

Wednesday, July 25, 2012

Which are the Warm and the Cold Blooded Creatures?

            We have often heard people being called cold-blooded but scientifically it is impossible. Do we know how this term originated? On the basis of body temperatures, all the living beings have been classified into tow categories- the cold blooded and the warm blooded.

Tortoise is a cold blooded animal

            Cold blooded creatures are those whose body temperature does not remain constant. Their body temperature changes according to the surrounding environment. The temperature becomes high during the summers and low during the winters. Interestingly, it changes even during the day- being less in the cool morning than in the hot noon.

            Frogs, tortoises, snakes, skunks, and some variety of fishes are the cold blooded creatures. During the winters, their temperature falls down to such a proportion that in order to survive they go into their holes under the earth. If they do not do so, their blood would freeze and they would die. During winters, they sleep in their holes. This is called the ‘hibernation’ period. These animals do not take food during this period. Even their physical processes get slowed down. When they come up on the surface after this period, they are usually very weak.

Dog is a warm blooded animal

            On the other hand, warm blooded creatures are those whose body temperature remains almost constant I winter or summer. The surroundings do not affect their body temperature. Man, bat, dog, cat, cock, cow, etc., come under this category.

            For example, the normal body temperature of man is 98.4 degree Fahrenheit. And of some other creatures it is as follows; bat, 104 degree Fahrenheit; dog, 102 degree Fahrenheit; cow, 101 degree Fahrenheit; cat, 101.6 degree Fahrenheit; cock, 102 degree Fahrenheit. If the body temperature, the animal may fall sick. They need more energy to maintain a constant body temperature.

            That is why the warm blooded creatures consume more food. Their physical processes continue normally, all round the year. There re special organs called hypothalamus in their bodies that control the temperature and do not allow it to go beyond or below a certain level. The heat lost and the heat produced is balanced, in these animals.

How do Parrots and Mynahs Speak Like us?

            For centuries, man has loved birds and kept them in cages, as pets. What is interesting is that some of these birds like the parrot and mynah can be taught in imitate the human voice. There are many species of parrots and mynahs, which if properly taught, can clearly speck many words and smaller sentences like human beings. How they can do it?

A Parrot can be trained to imitate human voice

            The parrot has a long and thick tongue. Earlier some people believed that this enables these birds to speak like human beings. But this is not true. We know that hawks and eagles also have long and thick tongues but they cannot imitate human voice. On the contrary, mynah, without having such tongue, is able to imitate our speech.

            Parrot ad mynah is more intelligent than other birds and thus can copy the human voice. Their speech and hearing mechanism are slow. As a result, the sounds coming out of their mouth resemble that of human beings. It is interesting to note that parrot and mynah themselves do not understand what they speak. They are able to imitate human voice by noticing our lip movements. A female parrot named ‘prudle’ now in the care of Iris Frost of East Sussex, won the best talking parrot like bird title of the national cage and advisory bird show in London for 12 consecutive years 1965-1976. This bird from Uganda was captured in 1958 from a nest. It knows a vocabulary of nearly 800 words.

            There are about 320 species of the parrots known to man. Most of these re green in color. Their beaks are sharply pointed and are red in color. Their length varies from 15 centimeters to 90 centimeters. Macaw, a long tailed parrot found I South America, is 90 centimeters long. They can live up to the age of 50 years if they are properly cared for. The females of all species of parrots lay white eggs.

Friday, July 20, 2012

How does a Firefly Glow at Night?

            The glowing fireflies or glow-worms have always fascinated man. They present a wonderful sight at night. Scientists have been trying to find out form the very beginning how and why fireflies emit light.

A chemical substance called luciferin present in the abdomen of a glow-worm combines with oxygen

            The firefly is, in fact, a flying worm. Both the male and the female of this worm have wings. In some species, however, females are without wings and are known as glow-worms. They are blackish and their bodies are very soft. They mainly live on the nectar of the flowers. They are found in large number in the tropical humid areas. They emit light in flashes.

            The light producing organ is located in the bottom of the abdomen in the rear side and controlled by nerves. It contains two chemicals named luciferin and luciferase. Luciferin combines with oxygen to produce light. Luciferase acts as a catalyst for this reaction. It is interesting to note that the light emitted by them produces on heat. Such as process of production of light is called bio-luminescence. Luciferin is the active luminescent material in the fireflies. The firefly can control the length and rhythm of the flashes from the abdomen.

            Fireflies usually emit yellow orange light. Today scientists can produce such lights in their laboratories. But that can only be done by extracting lucieferin and luciferase from the fireflies. Fireflies are usually 4 to 11 millimeters in length.

            Now one may wonder why a firefly produces light. The first reason is that both the male and female fireflies emit light to attract each other. The second reason may be that the light so produced may frighten birds and prevent for this, these fireflies produce a spectacular sight.

How does a Wall Lizard Get rid of its Tail?

            We may have noticed that sometimes when you try to kill a lizard, you only manage to cut off its tail. When an enemy attacks a wall lizard it often flees, leaving behind some portion of its tail. The detached tail keeps wagging for some time. This confused the enemy and the wall lizard escapes. That is how it protects itself forming its enemies.


            The wall lizard can easily detach a portion of its tail at its will. The bones in its tail are joined together loosely, so that any portion of the tail can be separated easily from the main body. When the tail is separated, it does not lose much blood because the ends of the blood vessels are almost sealed. It is, therefore, possible for the wall lizard to get rid of its tail. The lizard soon grows a new tail.

            Scientists have studied more than 3,000 species of lizards till date. It has been found that their bodies are usually divided into three distinct parts- head, trunk and tail. Most species have four legs. Although most lizards are hatched from eggs, a few are born directly. Most lizards feed on insects. A few of the larger species are more than 3 meters long. They are quite frightening with one blow of their long, strong tails. These lizards are mostly found in tropical countries. A number of African species live in tropical forests where they climb trees. Some of them have flattened flaps of skin, which can be stretched down between hind and forelimbs to jump from tree to tree. Lizards can run fast, and some can swim or even glide through the air.

            Like lizards, crabs and lobsters are also able to get rid of their legs in a way similar to the lizard detaching its tail. When a fish catches the leg of a lobster, it jerks away its leg and escapes. These are the defense mechanisms that enable these animals to survive.

How is Bats Different from Birds?

            For many years there has been a controversy over the fact that whether a bat is a bird or a mammal. According to the available fossil records, bats have existed on the earth form ore than 60 million years. They are found everywhere in the world except the poles. There are different varieties of bats. Scientists have so far studied more than 2,000 kinds of bats. Bat is a creature, which flies but yet is not regarded as a bird. But why is it so?

Being the only flying mammal, bat is a peculiar creature

            After a lot of arguments, bats have been categorized as mammals. Mammals are those animals whose females give birth to the young and suckle them. They cannot be called birds because unlike birds they do not have feathers on their bodies but have hair. Bat is the only mammal, which has wings for flying. It has wingspan of about 15 centimeters to 2 meters.

            Most of the bats live on insects and worms. In tropical areas, they feed only on fruits and flowers. There is some other kind of bats, which feed on the blood of other animals and birds- they are called the vampire bats. Due to this characteristic of some bats. People fear bats in general. The teeth of vampire bats are as sharp as needles and they even attack human beings and suck their blood.

            This unusual mammal has yet another peculiar quality- while resting it hangs itself upside down with its head facing downward and its legs holding tightly to the branch of the tree. The formation of its limb is such that it cannot stand erect.

            Another feature of bats is that they can fly at night as they produce high pitched sounds called ultrasonic waves which bounce off nearby objects and this echo is picked up by their large ears that convey the presence of obstacles.
           
            Did you know that the largest bat is the flying fox with a body length of over 40 centimeters? Bats usually have a lifespan of 20 years.

Thursday, July 19, 2012

How do Fish Breathe inside Water?

            What would happen of one of us were to drown in water? We would die because of suffocation as our lungs would get filled with water. But the fish can easily survive in water. It does not live outside water for long. Have we wondered how a fish can breathe in the water while human beings cannot?
Fishes breath through gills

            Except the lungfish, all other fishes breathe by means of a special structure called gills. They do not have lungs like human beings nor do they breathe through their noses. Their process of respiration is completely different from ours. They take water in their mouths for the purpose of respiration. This water flows over the gills and comes out through the openings behind the cover of gills. The cells of the gills absorb the oxygen in water.

            Since the surface area of the gills is quite large, the amount of oxygen absorbed is also considerable. The oxygen gets mixed in the blood and is circulated throughout the whole body. That is how it purifies the blood. The carbon dioxide produced in the body is brought to the gills by the circulating blood where it gets dissolved in water and passes out of the body. In this way, the cycle of respiration in the fishes continues.

            If the water is dirty, the fishes sometimes come up to the surface of water and take air in for breathing. However, they do not use gills for this purpose, the fish is a cold blooded creature. It is also sensitive to touch, taste, smell, etc. it has different organs for these functions. Scientists have already studied more than 20,000 different species of fishes. 

Tuesday, July 17, 2012

What are the Bites of Some Insects Dangerous?

            There are many kinds of insects that inhabit the earth. Some of these are capable of spreading dangerous diseases through their bites.

            Mosquitoes, tse tse flies, rat fleas, bed bugs, etc. are insects that can spread various diseases through their bites. When these insects bite any sick person and suck the blood, the germs of the disease pass into the bodies of the insects. When these insects bite a healthy person, they pass on to him the germs of that disease along with the saliva through a needle-shaped hollow organ. Before sucking the blood, they inject a small amount of saliva into our body to prevent the blood form clotting. By doing so the germs of the disease enter our body along with the saliva. These germs infect the healthy person and make him sick.

Female Anopheles is the carrier of the malaria parasite

            Malaria is caused by the bite of female anopheles mosquitoes, which, if we exclude wars and accidents, have mainly been responsible, directly or indirectly, for 50% of human deaths since the ancient times. Even today, despite major campaigns to eradicate malaria, the disease afflicts at least 200 million people every year in the world. Disease like the dangerous sleeping sickness is caused due to the bite of tse tse flies. Lice transmit typhoid. The rat fleas carry the germs of plague. Bed bugs cause skin diseases.

            However, there are some other insects that sting but do not spread any disease. Among them are honeybees and wasps. Their sting causes intense pain. The stings of these insects are located pain. The stings of these insects are located at the tail end and are connected to the poison glands. These insects use them as weapons for their self defense. When they bit us, they inject some poisonous substance into our body which causes swelling on the skin, itching and severe pain.

What are Mammals?

            Mammals are vertebrates or animals with backbones. They have large brains and a keen awareness of their surroundings. They are warm-blooded and have their skin covered with hair. Mammals give birth to their young ones, except for egg-lying platypus and spiny anteater, and suckle milk for the milk glands of females. You will be surprised to know that many animals, which are otherwise very different from one another, come under this category. For example, the cow, seal and bat have nothing in common, yet they come under the category of the mammals. Man is a mammal too.

Wolf
Lion
Cheetah
Polar Bear

            Many of the mammals are very peculiar. Some of these live on the land, some on trees while some others burrow holes inside the earth. There are some that live in water, also.

            Some of them are carnivorous while others are herbivorous. Some mammals are both carnivorous and herbivorous.

            Most of the time they live on the ground. The dugong, dolphin, whale etc. are mammals that live in water. Amongst the flying mammals are the bat and colugo.

            Platypus is another peculiar mammal, which does not give birth to its young ones but lays eggs. It is found in Australia. Pangolin is a mammal that does not have teeth and lives on ants. The wolf, lion, cheetah, bear, cat, seal- all are mammals. There are about 4000 distinct species of mammals – the ones given above are just a few of them.

Sunday, July 15, 2012

Why don’t Spiders Get Caught in Their Own Webs?

            Spiders have always fascinated man for a long time. The web made by a spider is a captivating thing. Spider is an amazing organism in many respects. This unusual creature is found all over the world and in all seasons. Its size varies from that of a small dot to 20 centimeters. There are some varieties of spiders that can live without water for a year. A giant spider called tarantula feeds on birds and can live for as long as 15 years. In February 1985, Charles J. Seiderman of New York City captured a female bird eating spider near Paramaribo, Surinam, which weighed a record peak of 122.2 grams. Normally most of the spiders live only for one year. The body of a spider is divided into the head and the trunk. It has eight legs and eight eyes.

The Spider does not get caught in its web because it has oil on its leg

            The silk that spiders fabricate for making their webs is produced in certain abdominal glands. A liquid in the form of fine thread comes out form a small hole at the top of its abdomen, which solidifies the moment it comes in contact with air. These threads are of different types. Some of them are sticky while other is dry and soft. The sticky thread helps the spider in catching its prey. As soon as a fly or a small insect touches or falls on the web, it gets entrapped in it. Now one wonders why the spider itself doesn’t get caught in its web.

            The reason the spider does not get trapped in its own web is due to a special kind of oil on its legs. In fact, when the spider moves across the web, it uses the dry-soft threads and is careful to avoid touching the sticky threads with its legs. Even if it does, the oily secretions on its feet prevent it form sticking and it moves along those threads easily.

            In England and Wales, there are more than 2,000,000 spiders in every acre of meadowland. Did you know that it has been estimated that in one year the spiders in the country eat a weight of insects that exceeds the total weight of the human population of England and Wales?

            Spider’s webs come in a variety of designs. Some of these are wheel shaped while some are shaped like a funnel. The sticky threads, which are meant for trapping the prey, are separately located.

Friday, July 13, 2012

Why don’t Some Trees Shed Their Leaves?

            Most of the trees and plants shed their leaves once a year usually during autumn, and new leaves sprout on them during spring. After the defoliation, these trees appear quite barren. The trees which shed leaves every year are called deciduous trees. However, there are other trees, which do not shed all their leaves at once, and thus they appear green throughout the year. Such trees are called evergreen trees. Why these trees do not shed their leaves at once?
Cypress Tree
Fir Tree
 Fir and cypress are well-known evergreen trees with dark leaves and hard wood

            The leaves of the trees, which undergo defoliation every year, live only for one year. On the other hand, leaves of the evergreen trees last for two to three years. As soon as leaf withers, it falls down and a new leaf takes its place. Thus all leaves of not fall at a time. As a result, the tree always retains a large number of leaves and this cycle continues.

            Among the well-known evergreen trees are pines and firs. Besides these, there are many other trees that always remain green. The Italian cypress found in Europe is one such tree. The olive plant also comes under the category of evergreen plants. Its oil is very useful to us. The magnolia plants are used for decoration because their white flowers are very beautiful and do not undergo defoliation.

            Perfumes are extracted from the evergreen plants of the rosemary. The juniper plants, having short and bitter leaves, which are found in North Britain, are famous for their greenness.

            In addition to these, other evergreen plants and trees are myrtle of Britain, oleander of North Africa, oak tree, ivy creeper, orange tree and tall palm tree. The tea plant also comes under the category of the evergreen plants.

Why do Camels have Humps?

            Camel is called the ‘ship of the desert’ because it has the ability to survive in a desert without food and water for six to ten days. It is able to withstand the loss of about one-third of their body fluid without danger. Its nose, ears and eyes are formed in such a way that the dust in the desert does not affect them. It is a very useful animal in the desert for it can carry heavy loads and can travel long distances easily with its padded feet.

Camel's humps is a storehouse of fats which provides energy during its long journey in the desert

            It is believed that a camel does not require food very frequently due to its body constitutions. It can store food and water for many days.

            Camel has a big hump on its back, which is a storehouse of fat. The camel used the fat so stored as a source of energy during its long journey in deserts. Inside its belly, it has two flask-shaped bags for storing water. When it does not get water, it uses this water. It is because of the fats and the water stored in the hump and the bags respectively that it is possible for it to go without food for a long time.

            Before starting on a long journey, a camel consumes large quantities of food and water so that enough fats and water get stored in its body. After a long journey the hump of the camel becomes lose, as the fat stored in it is almost exhausted. The water too gets exhausted. With the gradual intake of food and water, it becomes strong and healthy again.

            Camel has been man’s companion for ages. The people of Egypt lamed the camel around 3,000 years ago. Camels are mainly found in Africa and Asia. The one-humped camel is found in Africa, while the two-humped or Bactrian camel is found from Asia Minor to Manchuria and a few wild species are also found in Gobi desert.

Why do Flowers have Fragrance?

            Whenever we pass thorough garden during the spring season, the fragrance of flowers enchants us. Nature has endowed flowers with beauty, attractive colors, nectar and fragrance. Insects and flies get attracted to flowers and sit on them, and when they fly off, they carry with them the pollen grains to the flowers. This dispersing of pollen grains helps in cross pollination of flowers, as a result of which, seeds are produced. In this way, plants and trees multiply on their own.

Fragrance of flowers attract insects which help in pollination

            Different flowers contain different oils, which give them a specific fragrance. As these oils gradually keep on evaporating, the fragrance of the flowers spreads in the air. In fact, perfumes are prepared form the oils extracted from these flowers. There are various processes of making perfumes. In one process, flowers are kept in a pot through which steam is passed. The outgoing steam, takes out the oil, which is then passed through water. The oil brought out by the steam starts floating on water. This is then separated. There are other methods too.

            France produces the maximum amount of perfumes. It has been found that one ounce of rose perfume is extracted from 110 of rose flowers. Flowers like rose, Pandarus, lavender, jasmine, etc., are generally used for making perfumes.

            The anthocyanin pigment is responsible for producing red, blue and violet colors. The plastid pigment causes other colors. These pigments remain mixed in the juice of the flowers. The presence of chlorophyll and carotene make some flowers green. There are at least 200,000 kinds of flowers, ranging in size form the microscopic duckweed blossom with a diameter of 0.4 millimeter to the tropical Rafflesia with a diameter of 90 centimeter.

How do we Estimate the Age of a Tree?

            On the basis of age, plants are divided into three categories- Annuals, Bi-annuals and Perennials. Annuals are those plants, which take birth, grow up, give fruits and die within a year. Wheat, barley, gram, peas and tomato- all live for one year only. Bi-annuals are plants that live for two years. In the first year they bear only leaves, and in the second year- they bear flowers and fruits, after which they die. Plants like the foxglove and hollyhock come under this category.

The age of a tree can be estimated by counting the number of rings on its sliced trunk

            Perennial plants live for more than two years. Generally, they are called trees or bushes. They blossom and bear fruits many times. The trees of the Neem, Mango, Jamun (black plum), Guava, etc. come under this category. Some perennial trees have a life of more than 4000 years. The great sequoia trees found in California are reported to have life of more than 400 years. The yew trees live for 3000 years. The chestnut and the oak trees live for 2000 and 1500 Years respectively.

            But how is the age of any perennial tree determined?

            Scientists have devised a very simple technique to do this. This technique refers to the number of rings present in the trunk of a tree. If you cut off a slice form the tree trunk, you will notice many concentric rings in it. These rings are the record of the tree’s age. In fact, the trunk, underneath the bark, keeps on growing thicker with age.

            However, the wood, which grows in winters and autumn, is denser and harder as compared to those grown in spring and summers. This results in the formation of a ring in the trunk every year. These rings are brown and cream in color. Thus the number of rings counted from the centre of the trunk of a tree tells its age in years. It central portion is called the path.

Thursday, July 12, 2012

Why Some Fruits Sweet While Others is Sour?

            Some fruits like watermelons, guavas, grapes, apples, mangoes, etc. are sweet in taste while lemons, oranges, raw mangoes, etc. are sour. Each fruit has a distinct taste, which differs in some way from the taste of others fruits. The question arises- why does every fruit have a characteristic taste?

Sweet Fruits
Sour Fruits

            In fact, the taste of a fruit depends on the compounds present in it. In general, a fruit contains fructose natural sugar, organic acids, vitamins, starch, proteins, minerals and cellulose. All these are in a mixed state inside the fruit and are found in different proportions. Fruits having more fructose content taste sweeter, while those having more acids, taste sour. Orange is a fruit, which has almost equal quantities of fructose and acids; hence it tastes both sweet and sour.

            In general, raw fruits contain more acids but on ripening, the quantity of acid in them decreases and the amount of sugar increases. Hence raw mangoes are sour, but ripe ones are sweet. Raw bananas contain more of starch, but it gets converted into fructose when the fruit ripens.

            During the process of ripening, chemical changes take place inside the fruit by which the quantity of sugar increases thus adding to the sweetness of the fruit.

            We notice a difference of taste in two fruits of the same kind. Two apples or mangoes do not always taste alike. This is so because there are many varieties of the same fruit and also the variations in the quality of soil, climate, growing technique; manure, water, etc. change the proportion of the compounds inside the fruit resulting in the difference of taste.

            Sour fruits like lemons; do not taste sweet even after they are ripe, because of the presence of excessive amounts of acids.

Wednesday, July 11, 2012

How do Bees Makes Honey?

            We have ever wondered how the honey that we enjoy at our breakfast table each day is prepared. It is a fascinating story.

            Bees live in colonies. A honeybee colony consists of three categories of bees, the workers, the drones and the queen bee. The workers provide food and protection to the colony, the drones or fertile males who mate with the queen, and finally the queen, who lays eggs.

Honey is made by the worker bees in the beehive

            An average honey beehive contains one queen, 100 drones and 60,000 workers. The workers are female bees while drones are male. The queen bee lays more than 2,000 eggs a day and about 250,000 eggs in a season. It lays more than 1,000,000 eggs in its lifetime. Bees have life span of one to two years. The worker bees have many duties. In the beginning, they clean and polish the hives. After some days, they look after the larvae of the bees. Eventually, they go out to collect the nectar form flowers. Do you know how these bees make money?

            In fact honey is their food, and so, for the bees, making honey is like collecting food from flowers. The flowers contain sweet liquid called nectar. The bees drink this nectar and carry it to the beehive in their honey sacs. A bee must visit about 1000 flowers to fill its honey sac. The honey sac is located near the belly of the bee. A valve separates it from the belly. The sugar present in the nectar undergoes a chemical reaction. The water present in the nectar evaporates, and honey is formed, which can be stored in the hive for a very long time.

            There are many ways of extracting honey form the hive. The comb can be squeezed to yield honey. A machine called honey extractor is also available for removing honey from the combs. The color and taste of various kinds of honey vary depending upon collected. Honey contains many substances, which include two kinds of sugar- laevulose, enzymes, many vitamins, small amounts of proteins and acids. That is why honey is good for our health and fitness.

How Fast Can Animals Run?

            A few years ago, the American scientist and explorer, Roy Chapman Andrews came to India as the leader of an expedition team. One day as he was driving a jeep near the India Nepal border, he saw a Cheetah. Startled by the jeep, the Cheetah began to run, and he gave it a chase. In spite of driving at a speed of 80 kilometers per hour, he still lagged behind. Even at a speed of 100 kilometers per hour, the animal was ahead of the jeep before it finally disappeared into the jungle.

Cheetah, the fastest land animal, can run up to a speed of 96-101 kilometers per hour on a level ground

            Over short distances, i.e. up to 550 meters or 600 yards the cheetah or a hunting leopard in the open plains of east Africa, Iran, India, Turkemenia and Afghanistan can attain a maximum speed of 96-101 kilometers per hour 60-63 miles. Blackbuck comes next. It is a kind of deer. The third place goes to Mongolian gazelle and the pronghorn- the two species of deer. They can run at a speed of 95 kilometers 60 miles per hour. Lion occupies the fourth place. It can run at a speed of 88 kilometers 55 miles per hour.

            Rabbit and fox can run at a speed of about 75 kilometers 47 miles per hour. Horse, zebra and grey-hound can run at the speed of 64 kilometers 40 miles per hour. Buffalo and hare can run at the speed of 55 kilometers per hour, while giraffe and wolf at a speed of 50 kilometers per hour. The elephant can run at about 40 kilometers per hour. Kangaroo and sheep can run at a speed of 64 and 25 kilometers respectively while camel and pig can run at 18 kilometers per hour. The speeds of the four-legged animals given above are based on the conclusions of a large number of researchers.

            These animals cannot sustain these speeds for a very long time. At the most, they can cover a distance of a few hundred meters at these speeds.

How Does a Chameleon Change its Color?

            We observe that chameleon in the garden. It is an amazing kind of lizard, which often changes its color to merge with its surroundings and escape notice. This ability to change color is known as camouflaging.

Chameleons change their color because of the color-containing cells

            But how does a chameleon change its color? It can do so because of the color containing cells beneath its skin.

            Although the upper layer of chameleon’s skin is transparent, the layer just beneath it has cells containing yellow, black and red pigments. These pigments are granular in structure and the granules can easily move for one point to another in its body. When these cells increases at one point turning the color of the skin into black. And when they get scattered throughout the body, different colors are produced.

            This implies that the contraction and expansion of its cells are responsible for changes in the color of its skin. But why do these cells contract or expand? There are three reasons for this-

  1. Emotions of the chameleon play a role in changing its color. When a chameleon gets enraged or frightened, it turns black in color. When it is excited, yellow spots appear on its skin making it turn yellow.
  1. Light also affects chameleon’s color. When exposed to sunlight, its cells turn black due to the heat of the sun.
  1. Heat is also a reason for it to change color. Then it is exposed to hot and dark surroundings, its color turns green but at cooler temperature in the dark its skin turns light yellow.
            The ability to change its color provides the chameleon with many advantages, like protection from enemies and catching of its prey for food. Another interesting feature of a chameleon is that it can move one eye independently of the other. One eye can be looking forward while the other looks behind. This enables it to look at two things at a time.

Tuesday, July 10, 2012

Why do Elephants have Trunks?

            Elephant is the largest land animal. It is generally a timid and a peace loving animal, and it is for this reason that it can be easily domesticated and trained. An elephant can weigh up to 5 tones. It has four legs, which are thick and short. It has two ivory tusks, which protrude outside for the upper jaw. They use these tusks as weapons for defense. However, for chewing food it has teeth inside its mouth, which are not normally seen by us.

The trunk of elephant performs the function of hands, nose and lips

            The elephant live in herds. A group can have ten to fifty elephants. These groups of elephants keep on moving about in the jungles. In general, the elephant has the color of catechu with a blackish shade. Some elephants are white too. To day there are two types of elephants – African and Asiatic, which are found in the tropics of Africa and Asia. The African species are bulky with bigger ears whereas the Asiatic ones have high, domed forehead.

            The elephant’s trunk is a very important organ, without which it cannot exist. It may be called the lifeline of an elephant. It is as essential for the elephant as the hands are for us. The trunk is an extension of the nose and upper lip and performs the functions of hands, nose and lips. They have also developed a heavy head. Since a heavy head cannot be carried on a long neck, the elephants need long trunks to reach their food.

            The trunk has about 40,000 muscles. Because of such high number of muscles, it is flexible and strong. An elephant can lift huge wooden planks with its trunk. The tip of the trunk is just like a finger and is so sensitive that it can even lift a needle. It carries its food to the mouth with its help. It also drinks water with the help of the trunk. While bathing, it fills water in its trunk, curls it up and pours it over its back.

            The average life of an elephant is 90 years. Elephants are herbivores, eating a wide range of plants such as sugarcane, banana, etc. Elephants are used in jungles for carrying heavy wooden logs from one place to another. They entertain us in the circus.

            The tusks are used in making many decorative things.

Monday, July 9, 2012

What are the Difference between Fruits and Vegetables?

            Have you ever wondered what separates fruits from vegetables? What is the difference between these two categories of food? Most of us tend to think that the edible fleshy-part with seeds, which develop from the flowers of any plant, is called a fruit, whereas trunks, leaves and flowers of herbaceous plants used as food are called vegetables. But scientifically speaking, this belief is not quite correct.

Fruits and Vegetables

          According to botanists, the part of the plant containing the seed, which is produced by the ovary, is called the fruit. Whereas, the rest of the part used for food is called vegetable. Scientists have divided fruits into three basic categories: 1. Fruits with pulp and seed such as apple, orange, watermelon etc., 2. Fruits with stones, such as plum, cherry, peach, etc, 3. Dry fruits, such as corn and wheat.

          The horticulturists have adopted a simpler method of classifying fruits- temperate fruits, tropical fruits and subtropical fruits. Temperate fruits like apples, apricots are raised in temperate climates, subtropical fruits such s grapefruit, lemon and olives need warm or mild temperature throughout the year, while tropical fruits like mango, papaya, banana and litchis, are those that can stand frost.

          Surprisingly a botanist categorizes beans, peas, cucumbers and marrows as fruits. Whereas cabbage, turnip, radish, cauliflower, onions, potatoes- all are vegetables. Quite a confusing classification!

          Well, we are not the only ones confused- it baffles the entire world. The tomato was the centre of a controversy for a long time in USA until the US. Supreme Court declared in 1893 that tomato is a vegetable from a commercial point of view and scientifically a fruit.

EVERGREEN POSTS