My Science School

            If a fish is taken out of water, its natural habitat, it will not live long. A fish does not have the ability to absorb oxygen from the air like us or any other land animal. However, a frog, although generally found in water, will not be harmed even if stays out of water for many hours. Some animals can live both in water and on land. Such animals are known as amphibians.

            The word ‘amphibian’ means double life. Amphibians are animals that are called by this name because they need both land and water during their life cycle. They start life in the water, and live on the land as adults. Amphibians are vertebrates; and therefore, they have a backbone. They are also cold-blooded. A cold-blooded animal is an animal that cannot regulate its own body heat. So, an amphibian depends on its surroundings for warmth and its body temperature varies according to the surroundings.

            Amphibians have no hair, feathers or surface scales. The reason is that they can breathe through their skin, although some amphibians have lungs as well. Frogs and toads are some of the most common amphibians and therefore, all of us have seen an amphibian at some time or the other.

           We all know that the giraffe is the tallest animal in the world. Some males reach 5.4 metres in height and weigh up to 907 kilogrammes.

            Everything about this curious animal is long. Its neck alone is over 1.8 metres long and weighs 272 kilogrammes. The legs of a giraffe are also around 1.8 metres long. If none of that length was enough for these spotted giants, they have yet another tool to reach up to tall tree branches, their tongue. Giraffes’ tongues are 45 centimetres long – long enough to reach around the thorns of the acacia trees whose leaves are their favourite food. This lanky animal has a long heart too. Its heart is 60 centimetres long and weighs about 11 kilogrammes! Its lungs can hold 55 litres of air! Therefore, it is no wonder that they are considered giants among animals.

            A giraffe needs a lot of food since it is so big. This mammal eats up to 34 kilogrammes of food per day. When they do get thirsty, giraffes have to spread their legs and bend deep down, to drink from a lake or stream!

            Both male and female giraffes have two distinct, hair-covered horns. Male giraffes use their horns to fight playfully with one another. As male giraffes age, calcium deposits form on their skulls and other horn-like bumps develop. The pattern on a giraffe’s coat is good camouflage. Many have been fooled into mistaking a giraffe for an old dead tree!

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               Some animals love spending time in the water. They feel more secure and more powerful when they are in water. The hippopotamus is one such animal that makes the river its home.

               The animal, which is also known as the hippo, is found only in Africa. A hippo is smaller than the rhino, but is still very big; an adult weighs around three and a half tonnes. It has four toes on each foot, with each toe ending in a hoof like nail.

               Hippopotamuses enjoy spending time in water. That is why the Greeks named the animal a ‘river horse’. They spend up to 16 hours a day submerged in water. This keeps their massive bodies cool. Hippos are good swimmers, and can hold their breath underwater for up to five minutes. They are often large enough to simply walk or stand on the lake floor. Their eyes and nostrils are located high on their heads, which allows them to see and breathe while their bodies remain underwater.

              Hippos have huge mouths. We are often misled to believe that the animal is yawning when it opens its mouth wide. In fact, hippo is preparing to fight and its wicked-looking tusks can inflict terrible wounds on its enemy.

               At sunset, hippopotamuses leave the water, and travel up to 10 kilometres overland in a night to graze. They consume around 35 kilograms of grass. If they are threatened on land, they will rush back to the water.

               The rhino is a strange, wild animal due to its peculiar horn on its nose and thick skin. The rhino is probably the largest land animal after the elephant. Rhinos are very heavy, and the white rhino of Africa weighs around four tonnes!

               The skin of all rhinos is hairless, except for a brush of bristles at the tip of the tail. The skin is also very thick and this allows rhinos to rush through thorny thickets without hurting themselves. Rhinos generally have poor eye-sight, but their sense of smell is very keen.

               The word ‘rhino’ is short for rhinoceros, which means ‘horned nose’. Unfortunately, the primary cause of the rhino’s extinction is its horn. These animals are being hunted and slaughtered so that their horns can be made into dagger handles or crushed to make certain medicines. In fact, rhinos are being killed at such an alarming rate that in a matter of 20 or 30 years, there may be no rhinos left at all!

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                  The wild is a place of uncertainties and dangers. Animals use various ways to escape from their enemies. While some use their speed and power to escape predators, others have natural camouflaging techniques.

                  A zebra’s stripes are believed to be for camouflage-the patterns confuse the enemy, and make it difficult for predators to identify a single animal from a running herd. These stripes are unique to individual zebras, as no two zebras have identical stripes on their body. Due to their uniqueness, stripes may also help zebras recognize one another.

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            Among the animals that Man has domesticated, the horse is probably the most powerful animal. Horses have been our friends for thousands of years in our travels, wars and industries; there is a variety of horses among both wild and domesticated species. Today, however, there are very few wild horses left. In fact, the only wild horse is the Przewalski’s horse.

            Zebras are large, fast-running mammals that live on the African plains. They are social animals that spend time in herds. They graze primarily on grass. Zebras have horse-like bodies, but their manes comprise of short, erect hairs. Their tails are tufted at the tip and their coats are striped. In fact, no animal has a more distinctive coat than the zebra.

                Do you know that each zebra’s stripes are as unique as our fingerprints? No two zebra coats are exactly alike.

             There is so much diversity among mammals. Various factors relating to their environment, climate and availability of resources have resulted in the development of distinct species despite the apparent similarity in the appearance of these animals. Among camels, Bactrian camels and Dromedary camels are such animals.

           Dromedary camels have only one hump on their back. They are very common in Africa and the Middle East. Bactrian camels, on the other hand, are native to the Gobi Desert in Mongolia, and have two humps.

          Bactrian camels differ from dromedary camels in other ways too. A bactrian camel grows a thick coat of hair in each winter. This coat of hair is temporary and falls off every spring. This is to deal with the extreme variation of temperature in the Gobi desert, where summer heat often goes up to 100 degrees Fahrenheit, and winter months can see significant amounts of snow. The dromedary camel, on the other hand, has uniform length of hair all year round.

          Yet another difference is that Dromedary camels are not found in the wild while a few wild Bactrian camels still exist in the Gobi Desert. Finally, Bactrian camels are much more mild-mannered than the hot-tempered dromedary camels.

              In the olden days, when science was not as developed as it is today, the ancient man made intercontinental travels by ships. He stored the necessary goods for consumption on his big ships. Just as ships cross vast distances over water, carrying men and goods from one shore to another, camels travelled over scorching deserts, carrying loads from one place to another. Any other animal would die of heat and thirst, but the camel is able to survive because it has abilities that suit desert conditions.

              Camels can go for days without drinking water. They can also drink from waterholes that are too bitter or saline for other animals. Camels drink 100 litres of water within 10 minutes and then live without drinking for 3 or 4 days.

              These mammals eat almost anything, regardless of how tough or how thorny it is. A camel has leathery mouth, tongue and tooth enamel, enabling it to eat thorny desert plants. A camel’s hump is not used to store water as is commonly believed. Rather, it stores fat. If food is hard to find, the fat in the hump provides energy for the animal. If a camel is starving, its hump shrinks!

              The camel’s fur allows excess body temperature to radiate out and protects them from cold nights. Camels have enough tear glands and double rows of long, curled eyelashes to protect their eyes from blowing sand. They can close their noses by contracting muscles during sand storms. Their broad, padded toes are insulated to avoid the sand’s heat. The strong, flexible webs of their toes prevent them from sinking into the sand.

              Now you will certainly agree that camels are amazing mammals.

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               Man has domesticated so many animals. Cats, dogs, cows, and parrots are some of them. However, scientists say that the dog must be Man’s first pet. Dogs were the first animals that people fed, on purpose. People have been taking care of dogs since about 13,000 BC in the Stone Age, even before the beginning of farming.

               The domestic dog is a member of the family ‘Canidae’, which includes wolves, foxes and the coyote. It is likely that in the beginning, dogs frequented the campsites of early man, trying to snatch some garbage to eat. At first, early man must have tried to scare the dogs away. However, after a while the hunters living in these camps realized that the dogs ate rats and helped to clean up garbage that drew flies and other insects. Therefore, campsites with dogs were cleaner and healthier than campsites without dogs. As a result, people living in these cleaner and healthier camps began to encourage the dogs by feeding them, and others began to follow their example.

               In the course of time, dogs have become more and more useful to Man. Today dogs are considered to be Man’s most loyal friend.

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            We have heard the story of the race between a hard-working tortoise and a lazy rabbit. Or was it a hares? We use these words interchangeably quite often because both look alike. However, they are not the same and there are some differences between them.

             One of the most important distinctions between rabbits and hares is that while hares are wild and have not been domesticated at all; one rabbit species has been domesticated. While both animals exist in the wild, people do not keep hares as pets.

              Rabbit babies are born blind and without fur, while the babies of hares are born with vision and fur. Rabbits live in colonies in underground burrows, while hares build a simple nest and rarely live in groups. The hare is also generally larger and heavier than the rabbit. With its longer hind legs and larger hind feet, it can jump farther than any rabbit and does not tire as quickly. The hare has longer ears than the rabbit and these ears have characteristic black markings. There is a difference in their food habits too. Rabbits prefer soft green foods like stems of grass and other vegetables, while hares prefer to gnaw on hardwood, bark and twigs.

            Now, did a rabbit or hare race with the tortoise?

            Do foxes fly? No foxes have ever been found flying so far, except in fairy tales. However, some fox-lookalikes have flying abilities. In fact, a species of bats are known as flying foxes. Flying foxes are a species of fruit bat. As you might have guessed, their diet consists mainly of fruits. They are named flying foxes because of their fox-like heads and reddish brown fur. There are over 160 species of flying foxes found widely through South East Asia and North East Australia, where they inhabit tropical rainforests.

             Like most bats, the flying fox is nocturnal and roosts in trees during the day in large groups called ‘camps’, which may contain thousands of individuals. They sleep hanging from branches by their feet and keep themselves cool by fanning themselves with their large wings. They are the largest bats. Some attain a wingspan of frightening 1.5 metres.

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            Can you walk in the pitch darkness of the night without the aid of a torch? Our eyes are made for light and day. Therefore, darkness presents us with uncertainty and fear. However, being nocturnal animals, bats prefer to be active in darkness. While they rest and sleep during day, bats venture out to find their food in the night. To help them find their prey in the dark, most bat species have developed a remarkable navigation system called echolocation. Echolocation works in a very interesting manner.

                  When bats are out hunting, they make high-pitched sounds. These sounds are so high-pitched that we cannot hear them. When these sounds strike a solid object, they bounce back as echoes. The bat’s ears pick up the echoes. By determining how long the noise takes to return, the bat’s brain figures out how far away an object is. The bat can also determine from the echo where the object is, how big it is and in what direction it is moving. This remarkable ability enables them to move about in the darkness without any trouble.

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                  Birds are very different beings from other animals in terms of their appearance, physical attributes, their ability to fly and reproductive system. No mammal has been identified with the ability to fly except bats. Bats are the only mammals that can fly. They fly like birds, by beating the air with their wings. However, a bat’s wings are not like a bird’s wings at all.

                  The wings of a bat are actually its forelimbs that have grown very long. Unlike other birds, its wings have no feathers - rather, a thin membrane stretches across the ‘fingers’.

                  The toes of the hind limbs are long, with curved claws that the bat uses for hanging from trees. Most bats feed on insects in the evening. Since bats sleep during the day and are active at night, they are called ‘nocturnal’ animals. They sleep upside down using their feet to grasp onto a twig or board. When it is cold, they hang close together.

                  There are more than 1000 species of bats in the world and they are found in every continent except Antarctica. Like other mammals, they give birth to live babies. The babies feed on their mother’s milk. Many bats have a special ability that allows them to find their way, and their prey, in complete darkness!

                  Not all mammals have the same food habits and some of them, in fact, have some very interesting food habits too. The smallest of mammals cannot hunt other animals for their food as bigger ones do. Therefore, they eat tiny insects. Insectivores are amongst the smallest of mammals and they get their name from the fact that they survive by eating mostly small insects. Insectivores include frogs, lizards, shrews and anteaters. They feast on insects, juicy worms, slugs and snails!

                  Insectivores form the third largest order of mammals after rodents and bats. Most of the insectivores are very small, even smaller than the fist of a child. A few, however, reach a foot long or more. The largest insectivore is the moon rat, which stretches 30 centimetres from the tip of its snout to the end of its tail.

                  In spite of their many differences, these animals are grouped together because their teeth are alike. Insectivores have many small teeth, and all insectivores have long slender snouts. These snouts are very useful in searching for insects in the earth, or under leaves and stones. Their bodies lose heat easily, so they need to eat frequently.

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                  While a kangaroo is a curious animal for us in India, it is not so for the Australians; because the animal is found there in plenty. So is the case with most marsupials. Now did that happen?

                  Millions of years ago, when the earth did not have the many continents it has today, all the marsupials lived on one huge continent. Over time, the large continent broke into smaller pieces. The marsupials that had found their most comfortable habitat in a particular geographic location remained only in two of the pieces-those that now form South America and Australia.

                  Gradually some of the South American marsupials moved north to live in North America. Many of the American marsupials died out when more ‘modern’ mammals like horses and cats developed. The only marsupial now found in America is the opossum.

                  However, since Australia is an island situated very far away from the other continents, the ‘modern’ mammals could not reach it easily. As a result, most marsupials today are found in Australia.

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