I would guess it's due to the fact that not all bats live in low light
conditions (think: many species of fruit bats that spend their lives in trees).
Mammalian evolution takes longer than it does for invertebrates: the time
between generations is much longer.
Diana
* * * * * * * * * * * * * * * * * * * * * * * * * * * *
Diana R. Tomchick
Professor
University of Texas Southwestern Medical Center
Department of Biophysics
5323 Harry Hines Blvd.
Rm. ND10.214A
Dallas, TX 75390-8816, U.S.A.
Email: diana.tomch...@utsouthwestern.edu
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On Dec 31, 2014, at 3:28 PM, Ken Harrington wrote:
Interesting article and makes me wonder why bats have such good eyesight if
it is not used to capture insects (food). This article seems to show that
bats which use echo-location for finding food use it exclusively and if it is
jammed they do not get the food.
What purpose do the eyes function as? Seeing as bats spend most of their
lives in low light level conditions, are their eyes working in a different
spectrum or frequency range that that used in conditions of white light? Do
they have a spectrum of eyesight that allows navigating narrow spaces in
total darkness?
Yeah, I know my mind works in strange ways but I have to question why
something such as eyesight (which takes up a large part of the brain to
process) is provided if it is not used for some type of survival technique
such as finding food.
Ken
Life isn't about waiting for the storm to pass - It's about dancing in the
rain.
Date: Tue, 30 Dec 2014 21:59:35 +
From: dirt...@comcast.net
To: s...@caver.net; Texascavers@texascavers.com; tag-...@hiddenworld.net
Subject: [SWR] It's bat vs. bat in aerial jamming wars
It's bat vs. bat in aerial jamming wars
https://www.sciencenews.org/article/its-bat-vs-bat-aerial-jamming-wars?mode=magazinecontext=189468tgt=nr
It's bat vs. bat in aerial jamming wars
Special wavering call sabotages aim
By Susan Milius
10:00am, December 19, 2014
SONAR WARS Of the 15 known kinds of squeaks and chirps that a Mexican
free-tailed bat makes, one looks like aerial sabotage.
Magazine issue: Vol. 186 No. 13, December 27, 2014
In nighttime flying duels, Mexican free-tailed bats make short, wavering
sirenlike waaoo-waaoo sounds that jam each other’s sonar.
These “amazing aerial battles” mark the first examples of echolocating
animals routinely sabotaging the sonar signals of their own kind, says Aaron
Corcoran of Wake Forest University in Winston-Salem, N.C. Many bats, like
dolphins, several cave-dwelling birds and some other animals, locate prey and
landscape features by pinging out sounds and listening for echoes. Some prey,
such as tiger moths, detect an incoming attack and make frenzied noises that
can jam bat echolocation, Corcoran and his colleagues showed in 2009 (SN:
1/31/09, p. 10). And hawkmoths under attack make squeaks with their genitals
in what also may be defensive jamming (SN Online: 7/3/13). But Corcoran
didn’t expect bat-on-bat ultrasonic warfare.
Mexican free-tailed bats fight sonar wars, jamming each other’s echolocation
signals in competitions to snatch moths out of the night sky.
Nickolay Hristov
He was studying moths dodging bats in Arizona’s Chiricahua Mountains when his
equipment picked up a feeding buzz high in the night sky. A free-tailed bat
was sending faster and faster echolocation calls to refine the target
position during the final second of an attack. (Bats, the only mammals known
with superfast muscles, can emit more than 150 sounds a second.) Then another
free-tailed bat gave a slip-sliding call. Corcoran, in a grad student frenzy
of seeing his thesis topic as relevant to everything, thought the call would
be a fine way to jam a buzz. “Then I totally told myself that’s impossible —
that’s too good to be true.”
Five years later he concluded he wasn’t just hearing things. He and William
Conner, also of Wake Forest, report in the Nov. 7 Science that the
up-and-down call can cut capture success by about 70 percent. Using multiple
microphones, he found that one bat jams another, swoops toward the moth and
gets jammed itself.
Corcoran says that neighborly sabotage could be especially valuable for the
highly sociable Mexican free-taileds (Tadarida brasiliensis). “If you live in
a cave with a million bats,” he says, “you have to go out and find food — and
compete with a million bats.”
JAMMED SIGNAL Three video clips filmed outdoors at night show Mexican
free-tailed bats (the larger white shapes) hunting tethered insects (smaller
white shapes). The first clip shows a successful midair catch, and the rest
show how jamming calls foil the attempts. Credit: A.J. Corcoran et
al./Science 2014.
DirtDoc
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