The fluttery flight of many bats makes them seem less than in control, but bats actually are every bit as good flyers as birds. Having evolved flight independently from other flying animals, they do things differently than birds, pterosaurs, and insects. One aid to flight that bats use has to do with the efficiency of changing the wing's upstroke to the downward power stroke. This could be done by expending energy in contracting the muscles that pull the wing downward.
Bats can do it differently. At the top of the upstroke, a projection on
the end of the upper arm bone locks onto the shoulder blade. The shoulder blade is
attached to the body by an array of muscles that act as passive shock absorbers as
they're stretched. Like rubber bands, they recoil as they drag the shoulder blade
to a halt, returning the bone to its original position, ready to absorb the shock of
the next upstroke. If this had been done by design rather than evolution, one might say
it's a stroke of genius!
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.