Category Plants & Animals

          Animals like cow, buffalo, sheep, goat and camel have the habit of swallowing their food first and later bringing it back into the mouth to chew it at leisure. Such animals are called ‘ruminants’ or cud-chewing animals.

          Thousands of years ago, these animals could not protect themselves against their aggressive enemies like the lion and the tiger. In order to survive, they would swallow their food quickly without chewing it and run to a safe place where they would chew their food at leisure. But what makes such a strange process possible?

          The cud-chewing animals have a peculiar digestive system. Their stomach has four compartments — (1) Paunch or rumen (2) Reticulum or honeycomb bag (3) Omasum or manyplies and (4) Abomasum or the true stomach.

           When the animals swallow food, it goes into the first chamber. This is the largest of the four compartments. At this stage food is in the form of coarse pellet, i.e. the un-chewed portion of food. In this compartment it is softened and moistened. From here it goes to the second compartment, here it is converted into small pieces of convenient sizes called ‘cud’. At the time of chewing, the cud comes back to the mouth through a process called ‘regurgitation’. After it is chewed it goes into the third compartment. From here it passes on to the stomach where digestion takes place. Unlike other ruminants, camels do not have the third compartment.

           Cows, sheep and goats do not have any teeth in the upper jaw. Instead, the gums form a tough pad. So, with the help of the lower teeth and this pad these animals graze and take in food. 

          Snakes are long reptiles, having no legs. They probably evolved from a group of lizards that took up a burrowing way of life. Snakes are cold-blooded animals and are found in all parts of the world. They move along by wriggling their bodies. There are over 2400 kinds of snakes all over the world. Snakes have dry, smooth skin which they shed regularly.

          In fact all animals, including human beings, shed their skin due to natural wear and tear. Slithering (sliding or slipping) along the ground tends to wear out the skin of the snake, so it replaces it with a new one from time to time.

          The new skin grows underneath the skin and when it is fully formed, a fluid is secreted between the two to keep them apart and lubricated. The fluid behind the transparent eye scale clouds the eye and prevents the snake from seeing for a few days. It hides away and then splits the old skin at its lips by rubbing its head. The old skin is turned inside out as the snake wriggles out.

          Stories about vampires have been heard and talked about for centuries. It was said that vampires were the souls of the dead who stalked the country looking for victims to suck blood. These stories existed in Europe long before the blood-sucking South American vampire bat was known to people. In the 1700, explorers to South and Central America related stories about bats which sucked blood. These stories were exaggerated, and it was then that all vampires came to be thought of as bats. 

          Bats are the only mammals that can fly. They are small animals, not more than six to nine centimetres long. The vampire bat of tropical America lives on the blood of other animals and spends about half an hour each night feeding. Vampire bats do not really suck the blood through the puncture wounds made by their fangs; instead they lap it up from the small incision (cut) made by their razor-like front teeth. Their saliva contains an anti-clotting agent and the blood simply comes out while the victim continues to sleep. Although the amount of blood lost by the victim is usually small, there is a risk that this bat can transmit diseases such as rabies. A vampire needs about 30 gm of blood each night and it may take it from one or more animals. Vampires may also suck the blood of a sleeping man, horse, cow, dog or goat.

          Because bats like to rest in dark caves and come out only at night, they are greatly feared by animals. 

          Dog has been a faithful friend of man for thousands of years. Most dogs are kept as pets to do useful work like herding sheep or guarding buildings. Today, there are more than 100 breeds of dog of many colours, shapes and sizes.

          Dogs see a world that is blurred and has no colour. They are short sighted and see only shades of grey. But a dog’s sense of smell is thousand times better than that of ours. If it passes through one place, it can identify the same place again due to its acute smelling power. Therefore trained dogs are used in the modern security system. They can sniff illegal drugs and culprits. Customs officers use specially trained dogs for sniffing out illegal drugs. It is not necessary to open cases or crates – one sniff is enough for a dog, even if the drugs are packed in tins. 

          In our nasal cavity there is a yellowish area of about 250 sq. mm. This contains millions of hair-like cells which are sensitive to smell. These are called chemoreceptors. They are always wet because of the mucus present there. Chemoreceptors are connected to the olfactory bulb in the brain. When we smell something its particles along with the air reach the chemoreceptors. There they produce electrical impulses in the nerves. These electrical impulses reach the olfactory bulb and we identify the smell.

          The smelling power, in fact, mainly depends upon the size of the olfactory bulb. Bigger the olfactory bulb better is the smelling power. Studies have revealed that a dog’s olfactory bulb is bigger than that of a man that is why the dogs have a greater power of smell. Another reason for this characteristic is that the dog’s nasal cavity is wetter as compared to that of human beings. This wetness further helps in identifying the smells.

          Dogs make use of the strong sense of smell in feeding, hunting and identifying enemies. 

          Rabbit is a small furry mammal with a short tail and large pointed ears. Rabbits live in burrows in the ground. Each burrow is the home of a single family. The first fossils which can be attributed to this family came from North America. But now they are found in most parts of the world. As compared to the rest of its body the rabbit has large-sized ears.

          Rabbit is a weak and timid animal and is usually surrounded by many enemies. Therefore nature has provided it with large ears to enable it to hear even the faintest of sounds. The large area of the ear catches most of the sound waves produced in the air and passes them into the inner ear. This enables the rabbit to detect its enemies in time and to run to safety areas.

         You must have noticed that a rabbit washes its ears by repeatedly licking its forepaws and rubbing them over the surface of its ears. It does this just not to keep its ears clean, but also to take into its mouth the natural oil which covers the ear surface. This oil is important in forming Vitamin D which in turn is necessary for the growth of the healthy bones. If the rabbit is prevented from doing this, it will develop rickets.

          Wild rabbits spend most of the day underground and usually come out for food only between dusk and dawn. They also have a keen sense of smell. They have long, hind legs which give them a good speed. A rabbit can run at a speed of 65 km per hour. Rabbits feed mainly on grass but eat other vegetation also. Their fertility rate is very high. Only their extraordinary fertility has enabled them to survive inspite of their many enemies. On an average a doe (female rabbit) produces 10 to 12 young ones every year. The natural enemies of rabbits are cats, dogs, foxes, minks, weasels and wolves. Man is the biggest enemy of rabbits because he hunts them for their skin, fur and meat.

               We see many kinds of fishes in ponds, lakes, rivers and seas. They cannot survive outside water. Whenever somebody gets drowned in water he quickly dies of asphyxia caused by obstructed breathing. On the contrary, the fish survives only in water and dies when taken out of it. Now the question arises: how does it breathe inside water? 

               Except the lungfish, all other fishes breathe by means of their gills. They do not have lungs like human beings nor do they breathe through their noses. They have peculiar process of respiration. They take some 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 oxygen in water is absorbed by the cells of the gills. 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. Carbon dioxide produced in its body is brought by the circulating blood to the gills where it gets dissolved in water and passes out. 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 species of fishes.