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Why do Beavers Build Dams?

There are two kinds of beavers: the American and the European. The European beaver, found in Norway, Poland, Germany and France, lives in burrows. But the American beaver builds a dam across a stream or lake to construct his home or lodge. The lodges are made of huge logs of trees. The American beaver constructs solid dams and lodges because …

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Why do bats make a high-pitched sound as they fly?

Bats use high-pitched sounds to find their way about. They are nocturnal animals. That is they move about by night. So they have developed their hearing to such an extent that they can find their way by a method known as echo-location. The blind-flying abilities of bats were first studied by Lazzaro Spallanzani (1729-1799). He surgically removed the eyeballs from …

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Why did Columbus sail westwards?

Christopher Columbus was an Italian from Genoa living in Portugal. Although in the fifteenth century most people still believed that the world was flat, others including Columbus, had come to believe it was round. If this was so, he argued, a ship could sail around the globe and return to its original starting point. Thus the shortest route to the …

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Why can owls see well at night?

The night vision of owls is 100 times as keen as that of human beings, because their eyes are especially adapted for seeing in the dark. But most are almost color-blind and the pictures they receive are slightly blurred. This is because their eyes contain more rod-shaped receptor cells than cone-shaped ones. Operating in bright light, cone cells sharpen details …

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Why are Vampire bats dangerous?

Vampire bats are dangerous because they carry rabies and other diseases and infect their victims as they suck the blood which is their only food. Vampire bats (Desmodontidae) are found only in South and Central America. They have extremely sharp teeth and pierce the skin of their prey so gently that the victim does not awaken. Blood is drawn into …

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Why are there 12 zodiac signs and not more or less?

The plane in which the earth orbits the sun is called the ecliptic. From earth, the sun appears to move across the ecliptic in one year. This circle of 360 degrees is divided into 12 equal sectors of 30 degrees each. Each of these segments is represented by one zodiac sign. The zodiac is the circle or belt, which the …

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Why are the people of Japan also known as Nipponese?

Nippon is the Japanese name for Japan. It literally means ‘the sun’s origin’, which is often translated as the land of the rising sun. The Japanese name Nippon is used mostly for official purposes, including on the currency, in the constitution, on postage stamps and at many international sporting events. Nippon first appeared in history only at the end of …

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