epauletted fruit bat Epauletted fruit bat (Epomophorus wahlbergi) feeding on wild figs. Jane Burton/Bruce Coleman Inc.

Almost all bat species hang upside down. Their feet have evolved to be relaxed in a clenched position (difficult for a human to imagine). When they’re ready to fly, they let go and gain momentum from falling, since their little legs and wings can’t give them the kind of lift birds get. However, there are six species of bats that don’t hang upside down. Most of these bats have suctioning pads on their limbs that let them stick to leaves or other surfaces.