Why is it so
Difficult
to
Swat
a
?
Perhaps
we are all too familiar with
the irritating experience of unwelcome winged
house guests buzzing obnoxiously above our
food, trying to share a bite of our meal. Flies feed
freely on both food and fecal matter, carrying
the devastating risk of transmitting enteric, eye or
skin infections. However, successfully murdering
these pesky little disease incubators is no mean
feat, as they seem to possess an arsenal of
abilities to evade the swing of death.
Flies are evolutionarily equipped for escape.
With a pair of compound eyes that provide
an a lmos t 360 ° f i e l d of v i s i on, they have
undisputedly one of the fastest visual response
times in the animal kingdom and are able to
track movements five times more quickly than
do human eyes. A study conducted in 2012
suggested that thei r rapid response time is
partially attributed to a physical contraction of
photoreceptors - specialised cells found on the
retina. These photoreceptors respond to light,
which in turn generate electrical responses that
are directed almost instantaneously to the brain.
In contrast, the typical mechanism of using
chemical messengers for transmission is much
slower [1].
In addition to their keen spatial awareness,
they are also equipped with three pai rs of
athletic legs, with the ability to adjust position
faster than you can blink. Their tiny brains are
able to process an incoming threat and prepare
their escape by aligning their legs to the optimal
position to hop in the opposite
direction of said threat, all within
100 thousandths of a second.
For instance, if the direction of
the threat is positioned in front
of the fly, it moves its middle legs
forward, leans back and extends its
legs, thrusting itself backward. They are
keenly aware of looming danger and
take into account their body position
whether they are grooming, feeding,
walking or courting. Thus, they are
required to integrate the visual and the
mechanosensory information to
adjust their pre-flight pose [2].
These insects have the ability to
turn flight muscles on and off incredibly
fast, contributing to their rate of successful
escapes. In order to save time needed
for electrical responses to travel from the
brain to the muscle, muscles that move
the wings bypass the brain completely
to undergo stretch activation – an
automatic contraction of a set of
muscles when they are stretched as
a result of the contraction in opposing muscles.
Decades ago, scientists have reported that flies
“freeze” mid-flight or mid-walk when they sense
air stream in the vicinity. Their antennae contain
two groups of neurons – one of which responds
to flowing air particles, and the other responds to
sound [3].
