Bats are the only mammals that can fly. Their feet are not strong enough to support standing or walking for a long time. They have a wingspan ranging from six feet to six inches.
But the wings donâ€™t produce enough lift to help them take off from a dead stop and the hind legs, too, are so small that they canâ€™t run to build up the necessary take-off speed. Hence, unlike birds, bats canâ€™t launch themselves into the air from the ground. But the animals have a unique physiological adaptation that lets them hang upside down without exerting any energy. For this, they fly into position, pull their claws open and find a surface to grip. This way, they can take the weight off their tired limbs. Their breast-feeding babies, too, have no choice but to hang in limbo with their moms. And together they reap the benefits of downward gravitational pull. Moreover, hanging upside down is a great way to hide from danger.
Bats invert our common beliefs regarding their eyesight. A nocturnal creature, the bat hunts its prey at night and rests for the eveningâ€™s events by day. Also, their food resources are limited. So from whatever little food they get, they must efficiently use their total energy for maintaining their basal metabolism, flying, reproduction, etc. Birds, being powerful fliers, have well-developed chest and wing muscles and spend more energy to take off from the ground, against the gravitational pull. Bats avoid spending precious energy for this process by hanging upside down in high raised ceilings. As they drop down from the ceiling they start flying. An intelligent energy conservation strategy indeed!
Sources: The Telegraph (Kolkata, India)