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Comment by btilly | Hacker News Reader

I thought I had understood moths vs bats a long time ago.

Then I read https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-... after watching Steve Blank's amazing talk on the Secret History of Silicon Valley. (About an hour long, see https://www.youtube.com/watch?v=ZTC_RxWN_xo, and well worth it.)

Yeah, moths are designed to be hard to echolocate. But bats find them anyways. The moth knows the bat is coming - they have ears as well. And finally the moth rubs its legs together, making a loud sound to deafen the bat, and then randomly dodges.

The bat knows the moth will do this, but has to guess which way at the critical moment, so only gets the moth half the time.

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You can often trigger this dodging reflex in moths with a simple broadband ultrasound generator: quick jingling a keychain of metal keys. A nearby moth will drop suddenly when it detects the "echolocation pulse" with its tympanic membrane.

The counter-counter-evolutionary strategy of moth-specialist bats is to "whisper", and bats of the genus Corynorhinus for example have comically large ears so that they can echolocate at very low amplitude in "stealth mode", avoiding detection by moths until the very final approach phase.

I'm not familiar with moths producing an active "jamming" signal, and have a hard time believing it'd be very successful given that bats often produce echolocation signals as loud as 110dB (though they drop amplitude and refine frequencies as distance to a target decreases), but my experience is exclusively with US bats.

Another problem with announcing that you're searching for and homing in on food at 110dB is that any other bats nearby can hear as well. I've recorded Tadarida producing a sinusoidal FM jamming signal to try and prevent a competitor from success.

Just from listening to the bats; it sounds to me like they spend at least as much time cussing at each other as they do pinging. I wonder how much information the bats gather from others' ping calls and also from the "other chatter" a crowd of bats produces.

Interesting, this reminded me of something I watched long ago about bat-moth interactions.

According to this documentary[1], the Tiger moth has it's own "siren" that "warns bats that it is poisonous", however upon further research I came across this article[2] which claims that it is indeed sonar jamming. Thought I'd share.

aside: it's amazing that I could find Alien Empire online.

[1]https://archive.org/details/AlienEmpireBattlezoneMetropolis

(the bat-moth part is just after 13:00)

[2]https://www.scientificamerican.com/article/sonar-jamming-tig...

Are there moths that have evolved the Panenka, making the sound, but not dodging at all (https://en.wikipedia.org/wiki/Panenka_(penalty_kick))?

Can’t the moth dodge in more than two directions?

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