A mosquito's tiny, low-weight body is the key to
its ability to survive flying in the rain, according to scientists.
A team from the Georgia Institute of Technology filmed the
insects as they collided with raindrops.
This showed that their bodies put up so little resistance
that, rather than the drop of water stopping in a sudden, catastrophic
splash, the mosquito simply combined with the drop and the two continued
to fall together.
The team report their
findings in PNAS.
As well as helping explain how the insects thrive in damp,
humid environments, the research could ultimately help researchers to
design tiny, flying robots that are just as impervious to the elements.
"I hope this will make people think a little bit differently
about rain," said lead researcher David Hu.
"If you're small, it can be very dangerous. But it seems that
these mosquitoes are so small that they're safe."
Dr Hu is interested in
understanding completely the "tricks" that insects use to survive being
so small.
After repeated attempts at what he described as the most
difficult game of darts ever, he and his colleagues managed to hit
flying mosquitoes with drops of water and capture footage of the result.
Each droplet was between two and 50 times the weight of a
mosquito, so what they saw surprised them.
Describing the the results, Dr Hu cited the Chinese martial
art of Tai chi.
"There is a philosophy that if you don't resist the force of
your opponent, you won't feel it," he explained.
"That's why they don't feel the force; they simply join the
drop, become one item and travel together."
When a moving object crashes into another, it is the sudden
halt that produces a damage-causing force. For example, when a car hits a
wall at 30mph, the stationary wall and the car have to absorb all of
the energy carried by that moving car, causing a great deal of damage.
The trick for a mosquito is that it hardly slows the raindrop
down at all, and absorbs very little of its energy.
Surviving the collision though, is not the end of the drama
for a tiny insect. It has to escape from its watery cocoon before the
droplet smashes the insect into the ground at more than 20mph.
This is where the insect's body, which is covered in
water-repellent hairs, seems to give it another crucial survival
technique.
Every mosquito studied in this experiment managed to separate
itself from the water drop before it hit the ground.
source : http://www.bbc.co.uk/nature/18294324
0 komentar:
Posting Komentar