The smallest bat in the UK is the pipistrelle. They measure approximately 4cm and weighs around 5 grams. The UK's largest bat, the noctule is around twice the size and can weigh up to 40 grams 

All UK bats eat insects, our smallest bat can eat around 3000 insects in a single night.  When there are fewer insects around in winter, bats go into hibernation to save energy. 

Bats are not blind, their eyesight is just as good as ours. However, at night, they rely on a sonar system called echolocation. When bats fly, they shout and listen to the returning echo from an object, the echo then gives them information about the size and shape of what is in front of them.