Category Zoology

Why do camels have humps?

          Camel is called the ‘ship of the desert’ because it has the ability to survive in the desert without food and water for six to ten days. They are 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 they are least affected by the dust of the desert. It is a very useful animal for the desert travellers and can carry enormous loads.

          It is commonly believed that a camel does not require food very regularly but this notion is not correct. Because of the peculiarity of its body constitution, it can store food and water for many days.

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

          In fact, before starting on a long journey, a camel takes large quantities of food and water so that enough fat and water get stored in the body. After a long journey, the hump of the camel becomes loose because the fat stored in it is almost exhausted. Even the water stored in the bags gets consumed. After the journey it becomes so exhausted that it lies down on the ground for a long time. With the gradual intake of food and water, it becomes strong and healthy again.

          Camel has been man’s companion for a long time. The people of Egypt tamed the camel around 3,000 years ago. Camels are mainly found in Africa and Asia. In Africa the one-humped camel is found while the two-humped or Bacterian camel is found from Asia Minor to Manchuria and there are still a few, living wild in Gobi desert.

 

Why do elephants have trunks?

          Elephant is the largest land animal of the present day. It is a mild and peace-loving animal. That is why it can be more easily domesticated and trained. An elephant can weigh up to 5 tons. It has four legs which are thick and short. It is easier to balance a heavy weight with the help of short legs. It has two ivory tusks which protrude outside from the upper jaw. These tusks are used by them as weapons for defence. However for chewing food it has teeth inside its mouth.

          The elephant lives in herds. A group has ten to fifty elephants. These groups of elephants keep on moving about in the jungles. In general the elephant has the colour of catechu with a blackish shade. Some elephants are white also. Today there are two classes of elephants – African and Asiatic and are found in the tropics of Africa and Asia. The African species are bulky with bigger ears whereas the Asiatic ones have high, doned forehead. 

          Elephant’s trunk is a very important organ, without which it cannot exist. It may be called as the lifeline of an elephant. It is as essential for the elephant as the hands are for us. It is an extension of the nose and upper lip. For elephant it 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, so 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. It can lift very huge wooden poles 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. To take baths it fills water in it, curls it up and pours that over its back. Thus, we can see how the trunk is very useful for the elephant.

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

Why do we perspire?

          Our body is like a furnace. The food we eat acts like fuel inside the body. It produces heat energy by the process of oxidation. Through this process about 2500 calories of heat is produced every day which can boil 25 kgs of water at 0°C. But what happens to this heat in the body?

          In our body certain metabolic activities are constantly taking place which do not normally allow the temperature to go beyond 98.4° F. Perspiration is one of the means through which the body furnace keeps its temperature normal. In fact, the body temperature is controlled by the ‘temperature centre’ located in the brain. This centre has three parts: control centre, heating centre and cooling centre.

          If the temperature of the blood falls below the normal due to some reason, the heating centre starts operating immediately. At the same time some special glands produce certain combustible chemicals which are used by our muscles and liver to raise the internal temperature of the body to the normal degree.

          On the other hand if the body temperature rises for some reasons the cooling centre goes to work. The process of oxidation slows down. Sweat glands start excreting sweat. Water, urea and some salts come out with the sweat. The sweat glands work fast only when the internal temperature of the body goes up. Sweat evaporates with the help of the body heat and this produces a cooling effect in the body. This process is similar to that of cooling of water in a pitcher during summer. Evaporation always causes cooling. Sweat, therefore, is a very effective process of controlling the body temperature. It also cleanses the internal parts. Many substances, harmful to the body, are excreted out through the millions of pores of the skin in the form of sweat. When the humidity is high, sweating causes uneasiness because the rate of evaporation under humid conditions decreases.

Why do we resemble our parents?

          A cat produces a cat and a rat, a rat only. The neem tree does not bear mangoes and the mango tree does not bear guavas. The children of human beings resemble their parents. This is a universal truth that the offspring of all the living beings have close resemblance to their parents. Do you know why it is so?

          The answer to all these questions can be had from the genetics – the science of heredity. It deals with all those factors which are responsible for the close resemblance of the offspring to their parents. With the help of genetics we also come to know what traits in the young ones would be different from those of the parents. 

          Heredity is another name of the transmission of characteristics from parents to the offspring. These are inherited from the parents through very minute particles, called ‘genes’. The term ‘Gene’ was coined in 1909 by the Danish geneticist Wilhelm Johannsen (1857-1927). It is a part of the cell. There are some 20,000 genes in the nucleus of every cell. Out of these, some ten thousand of them are inherited from the mother and the other ten thousand from the father. All these genes are contained in 46 chromosomes in the nucleus having a diameter of .01 mm. At the time of conception 23 chromosomes come from the father and 23 from the mother. Thus there are 23 pairs of chromosomes in every cell. The gene is the unit of heredity. In every plant and animal, some genes come from the male and some from the female. 

          Gregor Mendel (1822-1884) a Christian priest and biologist from Austria, is called the father of genetics. He conducted many experiments on the pea-plants and formulated certain rules of heredity. These are known as Mendel’s Laws. He showed through experiments that the dominating genes of parents dominate the traits of the children also. For example, if the eyes of one parent are brown, and those of the other blue, then the eyes of the child would be brown since the brown colour has dominance over the blue. If the eyes of both the parents are blue then the eyes of the children will also be blue. Similarly children of tall parents tend to be tall and those of short parents short. In this way genes are responsible for the close resemblance of offspring to their parents.

Does a black cat bring bad luck?

          Many people all over the world regard the sight of a black cat as inauspicious. If a cat crosses our path, we take it as a bad omen. Do you know why a cat in general and a black cat in particular are considered inauspicious?

          In fact, it is nothing but superstitious to consider a cat inauspicious. This superstition goes back to a belief of thousands of years. The ancient Egyptians worshipped the cat. They had a goddess called Pasht whose head resembled that of a cat. They believed that this goddess had nine lives. Whenever a black cat died in Egypt, its dead body was preserved as a mummy (preserved corpse of a human being or animal). Remains of thousands of black cats have been recovered from a cemetery of Egypt. Killing a cat was then considered as an offence, punishable with a death sentence. Thus people had a great fear of the sight of a black cat.

               During the middle ages witches and witch doctors always used the skull of a black cat to prepare mysterious medicines. As a result people started thinking that a black cat was a bad omen. Thus people have been suffering from this superstition for many centuries. The truth is that no cat is inauspicious. The cat is a pet animal that was domesticated about 5000 years ago. 

Why do giraffes have a long neck?

               Giraffe is the tallest land animal in the world, but scientists are unable to explain how it got its long neck. A famous French zoologist, Jean Baptiste 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 were eaten away. This 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 upto a height of 5.5 m and weigh more than 1, 000kg. It is an herbivore. It chews its food in 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 cms long and so constructed that it can even eat the leaves of thorny plants. Its upper lip is long which helps it wrench off many leaves at a time.

               The colour of giraffes resembles the shadow of the trees and as such it is not easily visible to its enemies. It is usually yellowish-brown. Its ears are very sensitive.

               It can hear 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 ones have been found mowing like cow or ox in the zoological parks but most of them do not utter sounds. 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 kms per hour for an extended period of time without tiring. As far as fast running is concerned, it can beat even the fastest of horses. When it is attacked by some other animal, it retaliates with the help of 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. Lion always attacks it from behind because giraffe strikes with its head like a hammer.