14 August 2012
4 - 5pm
Venue: Ground Floor Seminar Room (G010), UniServices House, 70 Symonds Street, Auckland
A Bioengineering research seminar by Associate-Professor Stuart Parsons, Deputy Head of School (Academic), School of Biological Science
Bats are generally awkward crawlers, but the common vampire bat (Desmodus rotundus) and the New Zealand short-tailed bat (Mystacina tuberculata) have independently evolved the ability to manoeuvre well on the ground. The aim of our research was to describe the kinematics of locomotion in both species, and the kinetics of locomotion in M. tuberculata.
In particular, we sought to determine whether these bats move terrestrially the way other quadrupeds do, or whether they possess altogether different patterns of movement on the ground than are observed in quadrupeds that do not fly. Despite its strange terrestrial nature, M. tuberculata is also an active flyer and uses echolocation to orient, navigate and capture flying insect food. Most aerial hawking bats typically produce a single echolocation call per wing-beat cycle, with calls produced either late in the upstroke or early in the downstroke. The timing of call production correlates with the action of wing adductor muscles in the thorax. The contraction of adductor muscles is thought to increase abdomino-thoracic pressure, which should increase subglottal pressure for the production of high intensity echolocation calls. This is the theoretical mechanism by which the action of the wing muscles allows the bats to produce echolocation calls without any additional energetic input – bats are already compressing the thorax, so shouting at the right time costs almost nothing.
We studied the patterns of echolocation calls in M. tuberculata while in flight and when walking on the ground. Results of the analyses did show some patterns; however, they do not fully explain how energy is saved through linkage. Bat echolocating while walking appears to have no mechanism for saving energy.