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=magazine&context=189468&tgt=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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