![](https://nosymedia.info/wp-content/uploads/2019/08/bats-use-leaves-as-mirrors-to-locate-hiding-prey-in-the-dark.jpg)
The
mammals have a sixth sense that allows them to 'see' in pitch black conditions
by using the echoes of their ultra-sonic shrieks inaudible to humans.
Leaves reflect their sound blasts well, thus providing a natural cloaking device
for night-flying beetles, grasshoppers, moths, and insect larvae.
It
has been thought impossible for bats to find prey hiding in silence and
completely still in thick foliage.
Researchers have shown leaf-nosed bats can get around the 'acoustic camouflage'
by flying at leaves at angles greater than 30 degrees.
Sixth
sense: The mammals have a sixth sense that allows them to 'see' in pitch black
conditions by using the echoes of their ultra-sonic shrieks inaudible to humans
HOW
DO THEY DO IT?
Bats
cannot find prey resting on leaves when flying at them at acute angles less than
30 degrees as the echoes are reflected too strongly from the foliage - masking
the insect.
But
Dr Geipel and her colleagues the sound is reflected away from the source and
leaves act like a mirror, just as a lake reflects the surrounding forest at dusk
or dawn when the approach angles are greater - making a resting insect
detectable.
Study
leader Dr Inga Geipel, of the Smithsonian Tropical Research Institute (STRI) in
Panama, said: 'For many years it was thought to be a sensory impossibility for
bats to find silent, motionless prey resting on leaves by echolocation alone.
'This
study changes our understanding of the potential uses of echolocation. It has
important implications for the study of predator-prey interactions and for the
fields of sensory ecology and evolution.'
Her
team measured the echoes of artificial bat shrieks on leaves using a biosonar
device at more than 500 positions to create a full 3D model of the bats'
echo-location.
At
each position, they calculated the intensity of the echoes for five different
frequencies of sound that represent the frequencies of a bat's call.
The
researchers combined this with observations of real-life bats' approach angles
for prey resting on leaves using high-speed video camera.
They
found bats cannot find prey resting on leaves when flying at them at acute
angles less than 30 degrees as the echoes are reflected too strongly from the
foliage - masking the insect.
But
Dr Geipel and her colleagues the sound is reflected away from the source and
leaves act like a mirror, just as a lake reflects the surrounding forest at dusk
or dawn when the approach angles are greater - making a resting insect
detectable.
Analysis: Leaves reflect their sound blasts well, thus providing a natural
cloaking device for night-flying beetles, grasshoppers, moths, and insect larvae
They
predicted bats' optimal approach angle for finding insects on leaves was between
42 and 78 degrees.
Dr
Geipel then recorded bats approaching insects on artificial leaves at the
institute's Barro Colorado Island research station with two high-speed cameras.
She
reconstructed the three-dimensional flight paths of the bats as they approached
their prey and determined their positions.
And
discovered that, as predicted, almost 80 percent of the approach angles were
within the optimal range.
The
findings were published in the journal, Current Biology.
WHAT
DO EXPERTS PREDICT FOR THE FATE OF THE PLANET'S PLANTS AND ANIMALS?
Nature is in more trouble now than at any time in human history with extinction
looming over one million species of plants and animals, experts say.
That's the key finding of the United Nations' (UN) first comprehensive report on
biodiversity - the variety of plant and animal life in the world or in a
particular habitat.
The
report - published on May 6, 2019 - says species are being lost at a rate tens
or hundreds of times faster than in the past.
Many
of the worst effects can be prevented by changing the way we grow food, produce
energy, deal with climate change and dispose of waste, the report said.
The
report's 39-page summary highlighted five ways people are reducing biodiversity:
-
Turning forests, grasslands and other areas into farms, cities and other
developments. The habitat loss leaves plants and animals homeless. About
three-quarters of Earth's land, two-thirds of its oceans and 85% of crucial
wetlands have been severely altered or lost, making it harder for species to
survive, the report said.
-
Overfishing the world's oceans. A third of the world's fish stocks are
overfished.
-
Permitting climate change from the burning of fossil fuels to make it too hot,
wet or dry for some species to survive. Almost half of the world's land mammals
- not including bats - and nearly a quarter of the birds have already had their
habitats hit hard by global warming.
-
Polluting land and water. Every year, 300 to 400 million tons of heavy metals,
solvents and toxic sludge are dumped into the world's waters.
-
Allowing invasive species to crowd out native plants and animals. The number of
invasive alien species per country has risen 70 per cent since 1970, with one
species of bacteria threatening nearly 400 amphibian species.
Via Daily Mail