BAT FACT: Bats are the only mammals capable of true flight.

Bat wings contain the same bones as a four-fingered human hand. Indeed, a bat’s wings ARE its hands. A thin, strong membrane of soft, velvety skin spreads across these bones, connecting them to the bat's back and legs, like the fabric and ribs of an umbrella. The thumb clings to surfaces when the bat alights. 

The surface of a bat’s wings has small, sensitive bumps called Merkel cells. Each bump has a tiny hair in the center, allowing the bat to collect information about the air flowing over its wings so it can change the wing’s shape to fly more efficiently.

Excerpt taken from article first published on https://animals.sandiegozoo.org/animals/bat