For many years there has been a controversy over the fact that whether a bat is a bird or a mammal. According to the available fossil records, bats have existed on the Earth for more than 60 million years. They are found everywhere in the world except the poles. There are different varieties of bats. Scientists have so far studied more than 2,000 kinds of bats. Bat is a creature, which flies but yet is not regarded as a bird. But why is it so? After a lot of arguments, bats have been categorised as mammals. Mammals are those animals whose females give birth to the young and suckle them. They cannot be called birds because unlike birds they do not have feathers on their bodies but have hair. Bat is the only mammal, which has wings for flying. It has wingspan of about 15 centimetres to 2 metres. Most of the bats live on insects and worms. In tropical areas, they feed only on fruits and flowers. There are some other kind of bats, which feed on the blood of other animals and birds — they are called the vampire bats. Due to this characteristic of some bats, people fear bats in general. The teeth of vampire bats are as sharp as needles and they even attack human beings and suck their blood. This unusual mammal has yet another peculiar quality — while resting it hangs itself upside down with its head facing downward and its legs holding tightly to the branch of the tree. The formation of its limb is such that it cannot stand erect. Another feature of bats is that they can fly at night as they produce high-pitched sounds called ultrasonic waves which bounce off nearby objects and this ‘echo‘ is picked up by their large ears that convey the presence of obstacles. Did you know that the largest bat is the Flying Fox with a body length of over 40 centimetres? Bats usually have a lifespan of 20 years.