The bat is the only flying mammal. Although some other mammals, such as certain varieties of squirrels or lemurs, are referred to as "flying," they actually glide rather than truly fly. The bat has a wing membrane, consisting of nerves, tendons and blood vessels, on each side of its body. These wing membranes are supported and operated by the bat’s arms and four of its fingers, while its thumb remains available for gripping. The part of the wing membrane located in the lower part of the bat’s body can be manipulated into a pouch for holding onto the insects that the bat catches while flying.
More about bats: