Can a snake swallow an animal whole?

          All snakes fall into the category of reptiles. Scientists have so far studied more than 2,400 different kinds of snakes. Only about 8% of them are poisonous. They live on land, under the earth, in the water and on the trees. They are found in almost all parts of the world except in Polar Regions, New Zealand and in some other islands. Snakes are of different sizes and shapes.

          The constrictor snakes such as boa and pythons strike their prey with their teeth, and if the prey is large, then they wrap their bodies around it and squeeze until it suffocates.



          A snake can swallow large animals without chewing them, because its jaws are loosely attached to the skull and the two halves of the lower jaw are connected only by elastic ligaments (tissues). The mouth can therefore open very wide. By using its many backward pointing teeth the snake can gradually widen its mouth over its prey. In the meantime it breathes by bringing the wind pin opening forward to the front of the mouth. Swallowing and digestion of a large animal may take a long time and some larger snakes probably have only a few meals every year.



          The giant 100 kg anaconda snake of the boa family found in South America can swallow a whole pig or deer. In length it is about 10 metres. Due to the huge weight and length, it cannot move much. When some victim passes nearby, it coils its body around and constricts it. It takes several hours to digest the animal. The stomach of snakes produces powerful digestive juices that can break down even big bones of the victim.


What were the dinosaurs?

          For over 150 million years, the Earth was ruled by some of the most extraordinary creatures, the giant reptiles, popularly known as the dinosaurs. The age of the dinosaurs was the Mesozoic Era which lasted from about 225 million years ago to 65 million years ago. The term dinosaur was coined in 1842 by the English zoologist Richard Owens, from two Greek words deinos and sauros meaning ‘monstrous lizard’ or ‘terrible lizard.



          Dinosaurs were short-legged animals; most of them had gigantic bodies. Most of the giant reptiles were vegetarians, but the few flesh-eaters were indeed terrible. They were able to live both on land and in water. Some walked on two feet, others on four. Many dinosaurs had smooth skin while others had scaly skins and still others were armoured with large bony plates. Their mental development was quite slow and hence they had small brains.



          Dinosaurs are divided into two classes based on the difference between the structures of the hip bone: the saurischians or lizard hipped and the ornithischians or bird hipped. 



The Saurischians: The lizard hipped saurischians are further subdivided into two groups: the sauropods or plant eaters and the theropods or meat eaters.



         The sauropods (plant eating quadrupeds) were the largest dinosaurs. They include the massive brontosaurus. This huge creature grew to lengths of 24 m and weighed about 32 metric tons. The brontosaurs probably spent much of its time eating in the huge swamps that existed then. All of the sauropods had long necks and tails and walked on all four legs. Even larger than the brontosaurs were the brachiosaurs, largest of all the dinosaurs. The brachiosaurs weighed 77 metric tons and was 21 m long.



         The meat-eating theropods walked on their hind legs. They used their very short front legs for grabbing and tearing food. The tall and terrible theropods hunted the plant eating sauropods. The tyrannosaur was the largest meat eating animal ever to live on the Earth. It was 6 m tall and had teeth that were 15 cm long. Its head was larger than that of most dinosaurs and its front legs were too small to be of any use. 





The Ornithischians: The bird hipped ornithischians included both the armour plated dinosaurs and the duck billed dinosaurs. They were divided into four groups: ornithopods which walked on two legs and included some with bills like a duck’s; stegosaurs - which had great bony plates for protection; ankylosaurs - which were even more heavily armoured and ceratopians or horned dinosaurs.



          The disappearance of dinosaurs 65 million years ago remains a mystery. Several theories have been put forward to explain this.



          One theory suggests that dinosaurs became extinct due to the changing climate and want of food. Another theory suggests that the development of egg-eating mammals may have been the chief cause. Some scientists even think that certain harmful bacteria may have evolved and wiped out most of the dinosaurs. Only the first of these theories could receive general acceptance.



 


What is a sea-horse?

          The strange sea creatures, with large heads resembling the horse’s head, are in fact bony fish that belong to the family of Syngnathidae. Because of its head it has been rightly named as a sea-horse. Its body is covered with rough bony plates. Its tail is just like that of a snake.



         Sea-horses vary in size (10 cm to 30 cm) and colour, but they all have the same basic shape. They are found in all the oceans of the world. There are 100 species, which may be white, yellow, red or blue. When resting, a sea-horse wraps its tail round a piece of seaweed. Even when they want to feed, they hold on to seaweed with their tails and pick food out of the water as it floats by. 



          The sea-horse swims in an upright position, using its dorsal (back) fin to drive it along. The fin vibrates very rapidly (up to 35 times a second), yet it is the slowest moving fish. It hovers in the water propelling itself and even at top speed it would take a sea-horse about 2.5 days to cover a distance of 1 kilometre!



          The sea-horse is unusual in another way. The female seahorse has a long egg-laying organ which is used to place the eggs in sea-horse’s pouch on the male belly. During courtship the female places her eggs into this pouch and the male then fertilizes them. The male sea-horse can take care of up to three broods every year, with as many as 50 eggs in each brood. The eggs hatch in the pouch of the male and then the tiny young sea-horses leave the pouch about five weeks after the eggs are laid.



           Sea-horses face the least danger from its enemies because other sea fishes do not like to eat them at all.


How does an insect breathe?


          Insects are found all over the world. They are small creatures which fly, buzz around on a variable number of legs. They are by far the most numerous of all animal species. About 7,000 new insect species are classified each year. More than 850,000 different kinds of insects are already known to scientists. Roughly eight out of ten of the creatures on earth are insects. Insects range in size from tiny fleas which can be seen only through a microscope, to beetles as big as your palm.



          All insects have a similar body plan with three main parts: head, thorax and abdomen. On its head is a single pair of antennae or feelers, a pair of compound eyes, usually three small simple eyes, and a set of mouth parts which work sideways rather than up and down. The middle part or thorax carries three pairs of jointed legs and sometimes wings. The abdomen contains the stomach, reproductive organs and breathing tubes which open to the air through tiny holes called ‘spiracles’. Inside the insects body the tubes, called ‘tracheae’, branch repeatedly and end in the muscles. Normally oxygen passes through the tracheae into the tissue. Larger insects, such as bees and wasps, have air sacs in the muscles which can take in extra air as the muscles expand and contract. This increases the supply of oxygen to the muscles. These tubes work in the same way as man’s wind pipe. An insect breathes just like us, except that it may have hundreds of breathing tubes in its belly to take in the air. Among smaller insects these tubes do not take up much space.



           The rate of breathing depends upon the size of the animal. The larger the size, the slower is the rate of breathing. While the big animals like the elephant breathe about 10 times a minute, a mouse has to breathe about 200 times per minute. The oxygen taken in by the insects is needed to oxidize certain food materials for the body. Waste products, including water and carbon dioxide, are eliminated from the body by exhaling.



 


Which animal never drinks water in its entire life?


          All plants and animals need water for their survival. However, there is one creature which does not drink water in its entire life. It is the tiny kangaroo rat found in the South Western deserts of the United States.



          Kangaroo rats are an important part of desert life. They are often eaten by other animals for the water in their bodies! The rats can run very fast, covering 6 metres in one second, to avoid their enemies. They use their long tails as rudders (broad flat piece of wood) when jumping and can even change their course in mid-air.They move about by leaping, but with such an accuracy that they can jump over a cactus and land on top of a grass-hopper. Because of their long, powerful legs and the strong tail which resemble those of the kangaroo they are called the kangaroo rats. They grow to about 38 cm long, including a tail of 20 cm. They have short front legs, large heads and big eyes. Their silky fur is yellow or brown on the upper parts and white on the lower parts.



          How does the kangaroo rat survive without water? The physiological structure of desert plants and animals is such that they need very little water to survive. So efficient are the kidneys of the Kangaroo rat that it never has to drink water. All the liquid it needs is extracted from the plants, roots and seeds it eats. Yet it is enough to keep the kangaroo rat alive. It lives near bushes by making holes in the ground.



          The kangaroo rat’s legs are proportionately very long as compared with other parts of the body. When two kangaroo rats fight, it appears as though they were fighting with sticks. 


What is a coral?

           Man has been using the red corals in the jewellery since ancient times. Romans used to hang pieces of coral around their children’s necks believing that it could prevent and cure diseases. In some parts of Italy, it is still worn to ward off the ‘evil eye’. Indians also use coral pieces as jewels in their rings and other ornaments. But what is a coral?



          Coral is the hard dried skeleton composed mainly of calcium produced by colonies of small animals known as ‘coral polyps’. They are small invertebrate organisms. The polyps of living coral live in tiny cups in the skeleton formed beneath and around their outer body. The polyp first attaches itself to a rock beneath the surface of water. The young ones are born as small buds from its body. When the old polyp dies, the living polyps remain attached to its skeleton and produce more buds. In this way, corals gradually build up into colonies of many millions. As layer upon layer of coral is built up they actually form reefs and islands in the ocean.



          Corals can be found in most seas, but the reef-forming ones prefer warm, shallow water. A coral reef begins as a fringing reef along the shore of a continent or island. Corals are found mainly in the warm tropical waters of the Pacific, the Indian Ocean and the Mediterranean Sea. We get red and pink corals from polyps found in the Mediterranean Sea off the coast of Africa and Italy. Corals begin to shine when they are polished. These are mainly used in ornaments. 





 

Can a squirrel really fly?

          The squirrel is a familiar animal seen most everywhere. It is an animal found in every part of the world, except Australia. There are about 320 kinds of squirrels all over the world. They may be as large as cats or as small as mice. They can be divided into two general groups – the ground squirrel and the tree squirrel. Apart from these, there are flying squirrels too.

          Most people think of squirrels as a kind of rodent that is good at climbing. The tree squirrels have a long bushy tail that helps them to steer and keep their balance. They can leap 3 metres to reach from one tree to another. The woodchuck, marmot, chipmunk and prairie dog are the tree squirrels.



          Flying squirrels jump 10 times farther than that. These little creatures have flaps of skin between their front and back legs. These flaps form a parachute when a flying squirrel jumps and spreads its limbs. This helps it to glide through the air. If attacked in the mid-air by an enemy like the owl it turns back immediately to the tree and protects itself by hiding in the tree trunk. They have soft fur and large eyes and are 8 to 60 cm (3 to 24 inches) in length exclusive of tail. They live on trees and unlike other squirrels they seldom come to the ground. They are nocturnal animals and can see clearly in the dark. They can glide up to 60 m. The flying squirrel, like the tree squirrels, feed on leaves, twigs or seeds.



          There are about 35 species of flying squirrels known to man today. They are found in North America, Africa, Europe and some parts of Asia. We scarcely get to see them because they usually sleep during the day.



 


What is a flying fox?


          The flying fox is not really a fox, but a large, fruit-eating bat. There are 175 species of flying fox, and unlike most bats they have large eyes and long muzzles. It is their fox-like face that led to the name ‘flying fox’. They fly at dusk in search of fruit, relying mainly on sight and smell to find their way. Flying foxes are found in Asia, Africa, Australia and the islands of the Pacific.



          Most bats are small in size and look like mice. They are insect-eaters. Their wing-span is rarely as much as 30 cm. The biggest of all bats are the fruit eaters or flying foxes. One bat – the Kalong or Malay fruit bat has a wing-span of 1.5 metres. They have long sharp teeth with which they can even break a coconut. They weigh up to 1.5 kg. Unlike other bats, flying-foxes have well developed eyes which enable them to find their way by sight and not by sound waves. Their love for fruit makes them nuisance for orchards. Flying foxes live in thickly populated areas and make their homes in trees, resting close to a suitable source of food.



          Bats fly like birds, yet, in fact, they are mammals. They are the only mammals that can truly be said to fly. Their wings do not have feathers, but are made of a thin sheet of skin stretched between the long ‘finger’ bones. In most bats the wings are also joined to the legs and tail. Other ‘flying’ mammals, such as the flying squirrels can only glide, but the bats actually fly.


Why do some animals chew their cud?

          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. 





 

Why do snakes shed their skins?

          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.


Does the vampire bat feed on blood?

          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. 


Why is a dog’s sense of smell better than that of ours?

          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. 


Why do rabbits have large ears?

          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.