Tiger moth jams bat sonar (2009) | Hacker News Reader

Tiger moth jams bat sonar (2009)

science.org

44 pointsFergusArgyll30 comments

There have been a number of articles that have highlighted the ongoing evolutionary development of measures and countermeasures with respect to bats and insects over the last 60+ million years.[0] Sort of a natural landscape that mirrors the ongoing battle in military developments (radar, stealth, etc).

[0] "Sound strategies: the 65-million-year-old battle between bats and insects" https://pubmed.ncbi.nlm.nih.gov/21888517/

"Moths and bats: An evolutionary war" https://www.nhm.ac.uk/discover/evolutionary-war-between-moth...

it's all an arms race for increased chances to produce offspring.

There’s a fantastic book called “An Immense World” by Ed Yong that covers the incredible range of sensory modalities found in nature. One of the chapters goes into depth on bats and sonar.

Here's the relevant wiki page for reference. https://en.wikipedia.org/wiki/Echolocation_jamming

Ok it jams sonar, but you don't need sonar if the target is making a noise, you just listen, don't you?

I couldn't read the full paper but the abstract didn't mention that they were going to discuss how the jamming worked

I think the bats do need sonar because they use it for echo ranging. You need an echo to determine range.

I could read the full paper and man they definitely talked about a few different noises the moths make and how effective each one is at deterring preying bats.

Free full paper:

https://www.researchgate.net/publication/26676734_Tiger_Moth...

Besides the fact that the sonar is needed for accurate ranging, as mentioned by another poster, these moths produce their sounds in response to the bat sonar, so their sounds would not be useful to find them without sonar.

As mentioned in the paper, there are also other kinds of moths which are poisonous and which do not jam the sonar, but which emit warning sounds that the bats learn to avoid.

Other moths also emit sounds, but those sounds do not prevent bats from hunting them, except perhaps for the first few times until a bat learns that those moths emitting sounds are good to eat, so their sounds do not have a jamming effect.

Bat (and human) echolocation is not based on distinguishing sonar pings in time domain, but rather listening to the frequency spectrum of the reverberating sound, ie. "measuring" the impulse response of the surroundings.

Sending a signal that resembles the echo pulses will skew the spectrum and confuse the listener.

In theory that information can be used to triangulate the "jammer" if you could measure the small difference in time from receiving in left vs. right ear but that's not how mammal brains process auditory signals.

So it's not like sonar in submarine warfare with hydrophone arrays and digital signal processing.

I don't know about bats, but humans most certainly do both.

Yes, but not at a resolution that would be useful for echolocation. Humans can't distinguish individual echo pulses with millisecond granularity needed for meter-scale accuracy, yet humans can learn bat-like echolocation skills.

I think the distinguishing factor is distance vs. direction. We can very accurately measure direction by hearing the difference of time between ears, but that alone doesn't measure distance.

The ability to distinguish direction from a sound is based on the human ear frequency response being very directional. Your left ear will hear a sound coming from the right very differently than from the left. This is predominantly because of the shape of your ear and your head being in the way.

There's no way humans can tell the time difference of about 50 microseconds between hearing with your left and right ears. If you have research to prove otherwise, I'm all ears (pun intended).

You can also easily tell the difference of sound coming from directly ahead vs behind despite the ears hearing the sound simultaneously.

There is a lot of research into psychoacoustics in the past few decades. And pretty cool demos where directional audio is generated on headphones by altering the frequency spectrum between left and right ears.

I wonder if moths being 'soft' is also an adaptation.

Is there any study that moth 'soft' covering is also a sound absorber, to allude bats. I didn't see it mentioned here.

zefrank mentioned this briefly in his latest video[0] showing a paper titled "Thoracic scales of moths as a stealth coating against bat biosonar"[1]

[0] https://www.youtube.com/watch?v=v-s714RNXHY

[1] https://royalsocietypublishing.org/doi/10.1098/rsif.2019.069...

That also makes a nice garden path passphrase: soft tiger moth scales evade bat sonar.

Waiting for bats to develop laser range finding capabilities.

Nice garden path sentence title there: both "jams" and "bat" have several completely different meanings and it took a while until my brain permutated the right ones.

(Tiger moth) jams (bat sonar).

I also had some fun thinking on a tiger moth jam, and how that may have batted a sonar.

Tiger also has its own meaning, which makes the parsing even harder.

Both 'tiger moth' and 'bat sonar' are noun phrases in which the first word is not the actual meaning of the phrase. So you have two of these weird noun phrases, topped off by ambiguity about the verb ('jam' vs 'bat').

Very tricky sentence to wrap your head around!

> Both 'tiger moth' and 'bat sonar' are noun phrases in which the first word is not the actual meaning of the phrase. So you have two of these weird noun phrases

That's not weird; it is the norm for English by a ridiculous margin. We do have some left-headed compounds ("pickpocket"), but they are very noticeable exceptions to an extremely strong rule.

Surely 'pickpocket' is that way because (there) 'pick' is a verb, not a noun? Like.. 'roast potato' or 'tryhard'. (To deviate way off course, isn't it also odd we don't say 'roasted potato', or 'roasted chicken', etc.? Or not in that context anyway, only if it was something like 'mashed or roasted?')

> Surely 'pickpocket' is that way because (there) 'pick' is a verb, not a noun? Like.. 'roast potato' or 'tryhard'.

No, the normal thing to do in modern English is to say "pocket picker"†, where the head of the phrase comes after the modifier. As you note, the other order remains possible in non-archaic forms ("tryhard", "kiss-ass"), but it is unusual.

"Roast potato" is already right-headed; it is a kind of potato, not a kind of roasting or an entity characterized by its practice of roasting.

† That is, the normal way to express this kind of concept, not the normal way to express the particular concept of a pickpocket, where a conventional word already exists.

Yeah ok roast potato was a bad (not a) example, I got hung up searching for a verb+noun one and lost track.

'pocket picker' illustrates my point though, you swapped the verb for noun form, and it became the other way around.

'kiss-ass' is the same again, or at least it arguably is. (And I would argue it: it alleges a person to be one who 'kisses ass', not who is the kiss on the ass itself.)

> 'pocket picker' illustrates my point though, you swapped the verb for noun form, and it became the other way around.

No, "pickpocket" is already a noun, and it means "pocket picker". Just like "kiss-ass".

'picker' compounded in 'pocket picker' is a noun, and 'pick' compounded in 'pickpocket' is a verb.

'kiss' ...

Suppose you want to describe someone by the action they perform. There is a normal way to do this, and "pocket picker" is an example of it.

There is also an extremely marked, almost-never-used way to do it, and "pickpocket" is an example of that.

What are you trying to say?

Sorry, you're right, they're not independently weird, but they're weird in this context.

Also, while they're not weird for a native speaker, a lot of other languages would also mark the adjunct or head noun somehow to remove any ambiguity.

Ah, garden path sentence! What a great term. I seriously had to read the title a couple times and thought initially it was an article on passphrases.

At first read I thought the title was a secure password example along the lines of "correct horse battery staple":

https://xkcd.com/936/

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